Interaction with 3-d objects

In Handbook of Virtual Humans, N. Magnenat-Thalmann and D. Thalmann (Eds.), John Wiley & Sons, UK, 2004, 303-322

Interaction with 3-D Objects

Marcelo Kallmann

Abstract. Among the several issues related to real-time animation of virtual human ac-

tors, the ability to interact with virtual objects requires special attention. Take as exam-

ple usual objects as: automatic doors, general furniture, or a lift. Interaction with such

objects can easily become too complex for real-time applications. Some of the related

problems involve: recognition of manipulation places, automatic arm and hand anima-

tion, and motion synchronization between actors and objects. The smart object ap-

proach is described here and can overcome many of these difficulties by storing all

needed interaction information within the object description. Interaction information is

defined during modeling phase, forming a complete “user guide” of the object. In this

way, virtual actors can simply access and follow such interaction descriptions in order

to accomplish some given task. Solutions to related sub-problems such as programming

object’s behaviors, interactions with multiple actors, or actor animation to manipulate

objects are discussed here, and detailed case studies are analyzed.

9.1 Introduction

Computer graphics systems are no longer synonym of a static scene showing 3D objects. In most nowadays applications, objects are animated, they have deformable shapes and realistic movements. Such objects “exist” in virtual environments and are being used to simulate a number of different situations. For instance, costs are saved whenever it is possible to simu-late and predict the result of a product before manufacture.

Although many technical issues are not fully solved, a lot of attention has been given to a next step: lifelike behaviors. The issue is to have virtual entities existing in virtual environ-ments, deciding their actions by their own, manipulating virtual objects and etc. As a natural consequence, computer animation techniques today are strongly related to artificial intelli-gence and robotics techniques.

It is still a challenge to animate a virtual actor that can decide its motions, reacting and in-teracting with its virtual environment, in order to achieve a task given by the animator. This virtual actor might have its own way to decide how to achieve the given task, and so, many different sub-problems from many areas arise.

One of these sub-problems is how to give enough information to the virtual actor so that it is able to interact with each object of the scene. That means, how to give to an actor the abil-ity of interaction with general objects, in a real-time application. This includes different types of interactions that can be considered. Some examples are: the action of pushing a button, opening a book, pushing a desk drawer, turning a key to then open a door and so on.

A human-like behavior would recognize a given object with vision and touch, and then, based on past experiences and knowledge, the correct sequence of motions would be de-

2 duced and executed. Such approach is still too complex to be handled in a general case, and not suited for interactive systems where real-time execution is required.

To avoid complex and time-consuming algorithms that try to model the full virtual actor’s “intelligence”, an alternate approach is to use a well defined object description where all properties, functionality features and descriptions of the steps to perform each available in-teraction are added to the geometrical shape description of the object. In that way, part of the most difficult thing to model, the knowledge of the virtual actor, is avoided. Instead, the de-signer of the object will use his/her own knowledge assigning to the object all information that the virtual actor needs to access in order to interact with the object. This more direct approach has been called the smart object approach [1] to animate actor-object interactions.

9.2 Related Work

The necessity to model actor-object interactions appears in most applications of computer animation and simulation. Such applications encompass several domains, as for example: autonomous agents in virtual environments, human factors analysis, training, education, virtual prototyping, and simulation-based design. A good overview of such areas is pre-sented by Badler [2], and one example of a training application is described by Johnson and Rickel [3].

The term object interaction has been employed in the literature mainly for the direct inter-action between the user and the environment [4], but less attention has been given to the actor-object interaction case.

Actor-object interaction techniques were first specifically addressed in a simulator based on natural language instructions using an object specific reasoning (OSR) module [5]. The OSR keeps a relational table informing geometric and functional classification of objects, in order to help the interpretation of natural language instructions. The OSR mo dule also keeps some interaction information: for each object graspable site, the appropriate hand shape and grasp approach direction. This set of information is sufficient to decide and perform grasping tasks, but no considerations are done concerning interactions with more complex objects with some proper functionality.

In most of the cases, actors and objects have proper behaviors, and behavioral animation techniques [6] [7] can be employed. Behaviors can follow the agent approach, where actions are decided based on sensing the environment [8] [9]. These domains give techniques that can be employed to approach some issues of the general actor-object interaction problem. The term object functionality will be sometimes employed here instead of object behavior, reflecting the fact that the objects considered here have simpler behaviors than actors. The following two sections will present the related work done divided into two main categories: the definition of object’s functionality, and the actor animation to perform interactions.

9.2.1 Object Functionality

In general, objects contain some proper functionality that needs to be defined. Some si mple examples are: after pressing a button the lift door will open, or only after turning on the printer that it can print. Such rules need somehow to be programmed inside objects, and different techniques may be employed.

3 Okada [10] proposes to compose object parts equipped with input and output connectors that can be linked to achieve different functionalities. State machines are also widely used. In particular, most game engines [11] [12] use hierarchical finite state machines, defined graphi-cally through user interfaces.

An important point to be taken into account is the ability to interpret the defined function-ality in parallel, in a synchronized way. As it will be shown later, it may happen that several actors interact with a same object, e.g. to enter a lift.

Several techniques used for general behavior definition cover some of these aspects. One specific structure to define parallel behaviors is the parallel transitions network (PaTNets) [13] [14]. Other works [15] cover the aspect of sharing resources with concurrent state m a-chines.

It is natural to think that the description of the object functionality should be associated with the object geometric description as well. Current standards for object description [16] are normally based on scene graphs containing some nodes to connect animation to external events, such as events from the user interface (mouse, keyboard, etc). This provides a primi-tive way to describe basic object functionality, but as it is not generic enough, it is always needed to make use of complete programming languages such as Java scripts. Thus, there is still place for standards on the description of functionalities.

A similar scenario appears in the feature modeling area, mainly on the scope of CAD/CAM applications [17] where the main concern is to represent not only the shape of the object, but also all other important features regarding its design choices and even manufacture proce-dures. In fact, suppliers of CAD systems are starting to integrate some simulation parameters in their models [18]. The knowledgeware extension of the Catia system [19] can describe characteristics like costs, temperature, pressure, inertia, volume, wetted area, surface finish, formulas, link to other parameters, etc; but still no specific considerations are done to define object functionality or interactivity.

The main point is that none of these techniques cover specifically the problem of describ-ing object functionality for actor-object interaction purposes. As it will be presented later, object functionality, expected actor behaviors, parallel interpretation of behaviors, and r e-sources sharing need to be solved in an unified way.

9.2.2 Actor Animation

Once the object functionality is somehow defined and available, actors need to access this information and decide which motions to apply in order to complete a desired interaction.

The actor motion control problem is very complex, and has been mostly studied from the computer graphics community, mainly targeting movie and game industries. Boulic [20] pro-poses a good overview of the employed techniques. Recently the motion control problem has also received contributions from the robotics and artificial intelligence domains.

For instance, from the robotics area, a classification of hand configurations for grasping is proposed by Cutkosky [21]. Following the same idea, but targeting animation of virtual actors, Rijpkema [22] introduces a knowledge-based grasping system based on pre-defined hand configurations with on-line adaptation and animation. Huang [23] also proposes a system for automatic decision of hand configurations for grasping, based on a database of predefined grasping postures.

Also from the robotics domain, planning algorithms are able to define collision-free paths for articulated structures. Koga [24] has applied such algorithms for the animation of the arms of a virtual actor obtaining interesting results. The main drawback of the method is con-

4 versely also its main advantage: because of its random nature, complicated motions can be planned, but with high and unpredictable computational cost, thus not currently applicable for interactive simulations. A huge literature about motion planning is available, mainly target-ing the motion control of different types of robots [25] [26], and companies start to appear to provide this technology [27].

Artificial intelligence techniques such as neural networks and genetic algorithms have been applied for the control of virtual bodies [28] [29] [30] [31]. Currently, these algorithms are too costly and can be only applied to limited cases. However, artificial intelligence techniques will probably become more powerful and usable in a near future.

Inverse kinematics [32] is still the most popular technique for articulated structure anima-tion. Some works can handle the animation of complex structures, taking into account several constraints [33]. Some works present specific implementations regarding only the movement of the actor’s arm [34] [35]. Although interesting results can be obtained it is still difficult to obtain realistic postures, specially concerning the automatic full body animation for reaching objects with hands. For instance, to determine a coherent knee flexion when the actor needs to reach with its hand a very low position. For a complete overview of the possibilities of Inverse Kinematics techniques, as well as other related issues, please refer to the Motion Control chapter of this book.

In another direction, database driven methods can easily cope with full body postures. The idea is to define pre-recorded (thus realistic) motions for reaching each position in the space inside a discrete and fixed volumetric grid around the actor. Then, when a specific position is to be reached the respective motion is obtained through interpolation of the pre-recorded motions relative to the neighboring cells. This is exactly the approach taken by [36] with good results achieved, but limited to the completeness of the database. Complementary, some works [37] propose techniques to adapt pre-recorded motions for r especting some given constraints. Database methods were also successfully used to determine grasping postures [38]. The main drawback of such methods is that they are not general enough: it is difficult to adapt motions to all given cases and also to handle collisions with the environment. However, some works start to propose solutions to handle collisions [39].

As a final conclusion, table 9.1 makes a comparison of these many methods, from the point of view of animating actors for general interactions with objects.

Realism Real-Time Generality Collisions Motion Database + + - -

Path Planning - - + +

Inverse kinematics - + + -

Table 9.1. Comparison of the many motion control methods, regarding: the realism of the generated movements, the real-time ability of computation, generality for being applied to different types of interactions, and the ability to handle and solve collisions with the environment and self collisions

5 9.3 Smart Objects

In order to simplify the simulation of actor-object interactions, a complete representation of the functionality and interaction capabilities of a given object is proposed to be used. The idea is that each interactive object contains a complete description of its available interac-tions, like forming a “user guide” to be followed by actors during interactions. Once objects contain such information, they are consi dered here to become “smart”.

9.3.1 Interaction Features

A feature modeling approach is used, and a new class of features for simulation purposes is proposed: interaction features. Interaction features can be seen as all parts, movements and descriptions of an object that have some important role when interacting with an actor. For example, not only buttons, drawers and doors are considered to be interaction features in an object, but also their movements, purposes, manipulation details, etc.

Interaction features can be grouped in four different classes:

? Intrinsic object properties: properties that are part of the object design, for example: the movement description of its moving parts, physical properties such as weight and center of mass, and also a tex t description for identifying general objects purpose and the design in-tent.

? Interaction information: useful to aid an actor to perform each possible interaction with the object. For example: the identification of interaction parts (like a knob or a button), specific manipulation information (hand shape, approach direction), suitable actor positioning, de-scription of object movements that affect the actor’s position (as for a lift), etc.

? Object behavior: to describe the reaction of the object for each performed interaction. An object can have various different behaviors, which may or may not be available, depending on its state. For example, a printer object will have the “print” behavior available only if its internal state variable “power on” is true. Describing object’s behaviors is the same as defin-ing the overall object functionality.

? Expected actor behavior: associated with each object behavior, it is useful to have a de-scription of some expected actor behaviors in order to accomplish the interaction. For exa m-ple, before opening a drawer, the actor is expected to be in a suitable position so that the drawer will not collide with the actor when opening. Such suitable position is then proposed to the actor during the interaction.

This classification covers most common actor-object interactions. However, many design choices still appear when trying to specify in details each needed interaction feature, in par-ticular concerning features related to behavioral descriptions. Behavioral features are herein specified using pre-defined plans composed with primitive behavioral instructions. This has proved to be a straightforward approach because then, to perform an interaction, actors will only need to “know” how to interpret such interaction plans.

In the smart object description, a total of eight interaction features are identified, which are described in table 9.2.

6 Feature Class Data Contained

Descriptions Object Property Contains text explanations about the o b-

ject: semantic properties, purposes, desi gn

intent, and any general information.

Parts Object Property Describes the geometry of each comp onent

part of the object, their hierarchy, position-

ing and physical properties.

Actions Object Property Actions define movements, and any other

changes that the object may undertake, as

color changing, texture, etc.

Commands Interaction Info. Commands parameterize and associate to a

specific part the defined actions. For exa m-

ple, commands open and close can use the

same translation action.

Positions Interaction Info. Positions are used for different purposes,

as for defining regions for collision avoid-

ance and to suggest suitable places for

actors during interactions.

Gestures Interaction Info. Gestures are any movement to suggest to

an actor. Mainly, hand shapes and loca-

tions for grasping and manipulation are

defined here, but also specification of other

actions or pre-recorded motions can be

defined.

Variables Object Behavior Variables are generally used by the behav-

ioral plans, mainly to define the state of the

object.

Behaviors Object and Actor

Behavior Behaviors are defined with plans composed of primitive instructions. Plans can check or change states, trigger commands and ges-tures, call other plans, etc; specifying both object behaviors and expected actors’ behaviors. These plans form the actor-object communication language during interactions.

Table 9.2. The eight types of interaction features used in the smart object description

9.3.2 Interpreting Interaction Features

Once a smart object is modeled, a simulation system is able to load and animate it in a VE. For this, the simulator needs to implement a smart object reasoning module, able to correctly interpret the behavioral plans.

There is a trade-off when choosing which features to be considered in an application. As shown in figure 9.1, when taking into account the full set of object features, less reasoning

7

computation is needed, but less general results are obtained. As an example, minimum comp u-tation is needed to have an actor passing through a door following strictly a proposed path to walk. However, such solution would not be general in the sense that all agents would pass the door using exactly the same path. To achieve better results, external parameters should also take effect, as for example, the current actor emotional state.

Fig. 9.1. The choice of which interaction features to take into account is directly related to many im-plementation issues in the simulation system

Note that the notion of a realistic result is context dependent. For example, pre-defined paths and hand shapes can make an actor to manipulate an object very realistically. However, in a context where many a ctors are manipulating such objects exactly in the same way, the overall result is not realistic.

A design choice appears while modeling objects with too many potential interactions. Es-pecially in the case of composed objects, it is possible to model the object as many independ-ent smart objects, each one containing only basic interactions. For example, to have an actor interacting with a car, the car can be modeled as a combination of different smart objects: car door, radio, and the car dashboard. In this way, the simulation application can explicitly con-trol a sequence of actions like: opening the car door, entering inside, turning on the radio, and starting the engine. On the other hand, if the simulation program is concerned only with traffic simulation, the way an agent enters the car may not be important. In this case, a general be-havior of entering the car can be encapsulated in a single smart object car.

The smart object approach introduces the following main characteristics in a simulation system:

? Decentralization of the animation control. Object interaction information is stored in the objects, and can be loaded as plug-ins, so that most object-specific computation is released from the main animation control.

? Reusability of designed smart objects. Not only by using the same smart object in differ-ent applications, but also to design new objects by merging any desired feature from previ-ously designed smart objects.

? A simulation-based design is naturally achieved. Designers can take full control of the loop: design, test and re-design. Designed smart objects can be easily connected with a simu-lation program, to get feedback for improvements in the design.

9.4 SOMOD

The Smart Object Modeler application (SOMOD) [40] was developed specifically to model smart objects. It was developed using Open Inventor [41] as graphics library, and FLTK [42] for the user interface.

Interaction Info. Less Computation, Easier Usage - Less General, Less Adaptability Agent Behaviors

Object Behaviors Object Properties

8 SOMOD permits to import geometric models of the component parts of an object, and then to interactively specify all needed interaction features. Features are organized by type, and a main window permits to manage lists of features. According to the feature type, specific dia-log boxes permit to edit the related parameters.

9.4.1 Object Properties

Text input windows are used to enter any text descriptions, with specific fields to describe a semantic name for the object, and its overall characteristics. These definitions can then be retrieved by simulators for any kind of processing.

An object is composed by assembling its different parts. The geometry of each part is im-ported from commercial modeling applications. Parts can then be positioned interactively using Open Inventor manipulators (figure 9.2). The same technique of using manipulators is adopted to define the movement actions that can be applied to each part. For example to de-fine a translation, the user displaces a part using a manipulator, and the transformation movement from the initial position to the user-selected position is then saved as an action. Note that actions are saved independently of parts, so that they can be later parameterized differently (defining commands) and applied to different parts.

Fig. 9.2. Defining the specific parameters of a drawer. The drawer is a part of the smart object desk, which contains many other parts. The image shows in particular the positioning of the drawer in rela-tion to the whole object

9.4.2 Interaction Information

Commands are specified simply by associating actions to parts, and giving a parameterization of how the motion should be applied to that part. Commands fully specify how to apply an action to a part and are directly referenced from the behavioral plans whenever a part of the object is required to move.

Positions and directions (figure 9.3) can be specified for different purposes. Each position (as each feature) is identified with a given name for later referencing from the interaction plans.

9 Note that all features related to graphical parameters can be defined interactively, what is important in order to see their location in relation to the object. Positions are defined in rela-tion to the object skeleton’s root, so that they can be transformed to the same reference frame of the actor whenever is needed, during the simulation. Note that smart objects can be loaded and positioned anywhere in the virtual environment and all associated information need to be transformed accordingly.

Fig. 9.3. Positions can be defined for different purposes. In the figure, many different positions (and orientations) are placed to propose possible places for actors to walk when arriving from any of the door sides

Gestures are normally the most important interaction information. Gestures parameters are defined in SOMOD and proposed to actors during interactions. The term gesture is used to refer to any kind of motion that an actor is able to perform. A gesture can only reference a pre-recorded animation to be played, but the most used gesture is to move the hand towards reaching a location in space using inverse kinematics. Figure 9.4 illustrates the process of defining hand configurations and locations to be reached. Such information can then be used during simu lations to animate the actor’s arm to perform manipulations with the object. It is left to the simulator to decide which motion algorithm should be applied. As it will be shown in section 9.5, inverse kinematics was used for the exa mples shown here.

Some extra parameters can be set in order to define if after the reaching motion is com-pleted, the associated part should be taken, put, or just followed. Following is used to simu-late interactions such as pressing buttons or opening drawers.

10

Fig. 9.4. The left image shows a hand shape being interactively defined. The right image shows all used hand shapes being interactively located with manipulators

9.4.3 Behaviors

The behavioral animation solutions presented here are specific for the actor-object interaction problem. For a more general and complete overview on behavioral animation techniques, please refer to the chapter Behavioral Animation of this book.

In smart objects, behaviors are defined using pre-defined plans formed by primitive i n-structions. It is difficult to define a closed and sufficient set of instructions to use, and a com-plex script language to describe behaviors is not the goal. The idea is to keep a simple format with a direct interpretation to serve as guidance for reasoning algorithms, and that non-programmers are able to create and test it.

A first feature to recognize in an interactive object is its possible states. States are directly related to the behaviors one wants to model for the object. For instance, a desk object will typically have a variable state for its drawers, which can be assigned two values: “open”, or “close”. However, depending on the context, it may be needed to consider another midterm state value. Variables are used to keep the states of the object and can be freely defined by the user to approach many different situations. Variables are defined by assigning a name and an initial value, and can be also used for other purposes from the interaction plans, as for instance to retrieve the current position of the actor in order to decide from which side of a door the actor should enter.

Interaction plans are defined using a specific dialog box (figure 9.5), which guides the user through all possible primitive instructions to use. The following key concepts are used for the definition of interaction plans:

? An interaction plan describes both the behavior of the object and the expected behavior of actors. Instructions that start with the keyword “user” are instructions that are proposed to the user of the object, i.e., the actor. Examples of some user instructions are: UserGoto to propose it to walk to some place, UserDoGest to tell it to manipulate some part using pre-defined gesture parameters (figure 9.5), UserAttachTo to say that the actor should be attached to some object part, as when entering a lift, etc.

? In SOMOD, an interaction plan is also called a behavior. Many plans (or behaviors) can be defined and they can call each other, as subroutines. Like programming, this enables build-ing complex behaviors based on simpler behaviors.

? There are three types of behaviors (or plans): private, object control, and user selectable. Private behaviors can only be called from other behaviors. An object control behavior is a

11 plan that is interpreted all the time since the object is loaded in a virtual environment. They enable objects to act like agents, for example sensing the environment to trigger some motion, or to have a continuous motion as for a ventilator. Object control behaviors cannot have user-related instructions. Finally, user selectable behaviors are those that are visible to be selected by actors, in order to perform a desired interaction.

? Selectable behaviors can be available or not, depending on the state of specified vari-ables. For example for a door, one can design two behaviors: to open and to close the door. However, only one is available at a time depending on the open state of the door. Behavior availability is controlled with an instruction CheckVar. Its use is exemplified in figure 9.5, and will be explaining in section 9.6 (case studies).

Fig. 9.5 Defining interaction plans: menu-buttons are used to list all possible instructions to use, and for each instruction, the possible parameters are listed in additional menu-buttons. In this way complex behaviors can be easily created.

Multi-Actor Interactions. If the object is required to interact with many actors at the same time, synchronization issues need to be taken into account. There are two levels of synchro-nization. The first one is to guarantee the interaction coherence. For this, interaction plans are responsible to correctly make use of variables to, for example, count the number of actors currently interacting with the object, correctly setting states and testing conditions to ensure correctness when multiple actors are accessing the same object, etc. Section 9.6.2 details a smart object door that is able to deal with several actors at the same time.

Another level of synchronization is to correctly manage the interpretation of several inter-action plans in parallel. This is independent of the object type and should be done by the simulator. A proposed procedure for this kind of synchronization is described in section 9.5.1.

Graphical State Machines. SOMOD plans are very simple to use for describing simple in-teractions and functionalities. They can still cope with much more complex cases, but then plans start to get more complex to design. It is like trying to use a specific purpose language to solve any kind of problems.

To simplify modeling the behaviors of more complex objects, SOMOD proposes a dialog box to graphically design finite state machines. The proposed solution is to start designing basic interaction plans, using the standard behavior editor (figure 9.5). Then, when all com-ponents have their functionality defined, the state machine window is used, permitting to define the states of the whole object, and the connections between the comp onents. At the end, designed state machines are automatically translated into interaction plans so that, from the simulator point of view, a single representation is kept, and all behaviors are treated as plans. Section 9.6.3 exemplifies how a state machine is used to si mplify the creation of a smart lift.

12 Templates. One important concept is to reuse previously defined objects and functional-ities, and a specific template loader was designed for this goal. The template loader window can import any kind of features from other smart objects. Note that some features have de-pendencies on other features. These dependencies need to be tracked and coherently loaded. In addition, names are automatically updated whenever conflicts with previously created names appear.

Extensions. SOMOD has been used for different purposes and different types of exten-sions have been integrated. Positions can be automatically generated to delimitate regions for collision avoidance when actors are walking. Behavioral instructions can simply call a user-defined function in Python language [43], virtually enabling any complex behavior to be coded. A VRML [16] exporter was also developed, however with limited animation capabili-ties.

9.5 Interacting with Smart Objects

When a smart object is loaded in a virtual environment, actors are able to access available interaction plans and interpret them. Two main issues should be considered when interpreting plans: how to synchronize the interpretation of plans in parallel, and how to animate the ac-tor’s skeleton whenever a manipulation action is required.

9.5.1 Interpretation of Plans

Each time an actor selects an interaction plan to perform, a specific thread is created to fol-low the instructions of the plan (figure 9.6). The situation is that a simultaneous access to the smart object is done when interpreting instructions, for example, that access variables or trig-ger motions.

A simple synchronization rule to activate and block the many processes interpreting plans in parallel is adopted. However, interaction plans still need to be well designed in order to cope with all possible comb inations of simultaneous access. For example, complex situations as the dining philosophers problem [44] are not automatic solved.

Long and local instructions. A simple built-in synchronization rule between threads is used. For this, plans instructions are grouped into two categories: long instructions, and local instructions. Long instructions are those that cannot start and complete in a single time step of the simulation. For example, instructions that trigger movements will take several frames to be completed, depending on how many frames the movement needs to finish. All other instructions are said to be local.

Plans are interpreted instruction by instruction, and each instruction needs to be finished before the next one is executed. When a plan is being interpreted by some thread T, all other threads are suspended until a long instruction is found. In this way, T will fully execute se-quences of local instructions, while all other threads remain locked. When a long instruction is reached, it is initialized, the other threads are activated, and T stays observing if the instruc-tion has finished. This scheme results with the situation where all activated threads are in fact monitoring movements and other long instructions, and each time local instructions appear, they are all executed in a single time step, while other threads are locked.

This approach automatically solves most common situations. For example, suppose that a smart lift has an instruction like: “if state of calling button is pressed do nothing; otherwise

13 set state of calling button to pressed and press it”. Suppose now that two actors, exactly at the same time, decide to call the lift. The synchronization rule says that while one thread is interpreting local instructions, all others are locked. In this way, it is guaranteed that only one actor will actually press the button. Without this synchronization, both actors would press the button together at the same time, resulting serious inconsistent results.

Fig. 9.6. For each actor performing an interaction with an object, a thread is used to interpret the se-lected interaction plan. Each thread accesses and controls, in a synchronized way, its related actor and object, according to the plan’s instructions

9.5.2 Manipulation Actions

To animate the actor’s skeleton for manipulation actions, Inverse kinematics is used, with different constraints based on the type of manipulation and on the goal location to reach with the hand.

An unified approach was designed targeting general manipulations with one arm. First of all, a manipulation movement is divided in three phases: reaching, middle, and final phases (figure 9.7).

All manipulation movements start at the reaching phase. In this phase, inverse kinematics is used in order to animate the actor’s skeleton to have its hand in the specified position. Then three cases can happen, depending on the parameters retrieved from the smart object: follow, take, or put. Parameters follow and take are used to specify the attachment of objects to the actor’s hand. The follow parameter indicates that the actor’s hand should then follow a specified movement. This is the case for example to press buttons and open drawers: the specified translation movement to animate the object part is followed by the actor’s hand, while inverse kinematics i s used in order to adjust the posture of the actor’s skeleton. The final phase has the default behavior to either keep the actors posture unchanged or to change it to a standard rest posture. This can be configurable and permits to chain other actions instructions or to left the actor in the rest posture. In this way long and complex manipula-tions can be subdivided in small pieces, each piece matching the schema of figure 9.7.

14

Additionally to the inverse kinematics motion to control the actor’s arm towards the speci-

fied location, the current hand fingers configuration is interpolated towards the specified final

configuration, and the actor’s head is set to look to the place of manipulation.

Constraints Distribution. The used inverse kinematics module was developed by Paolo Baerlocher [33] (see the Motion Control chapter of this book), and is able to control the full actor body with different types of constraints. The skeleton’s root i s a node between the pelvis and the spine, and which separates the hierarchies of the legs and feet from the hierar-chies of the spine, head and arms.

At the beginning of a manipulation, the a ctor’s skeleton sizes and the task position to reach with the hand are analyzed and different constraints are set.

? First, the inverse kinematics module is set to only animate the joints of the arm, shoulder, clavicle, and the upper part of the spine. This set of joints makes the reach volume space larger, as the actor can reach further positions by flexing the spine. However, a side effect is that even for closer positions to reach, the spine can move, generating weird results. To over-come this, two new constraints are created. Positional and orientation constraints, with low priority, are used in order to keep the spine straight as long as it is possible (figure 9.8).

? Secondly, if the goal position to reach with the hand is lower than the lowest position achievable with the hand in a straight rest position, a special knee flexion configuration is set. The joints of the hip, knee, and ankle are added to the allowed joints to be animated by the inverse kinematics module, and two new constraints, with high priorities, are added to keep each foot on its original position and orientation. This configuration makes the actor to flex the knees, keeping its feet attached to the ground, while the actor’s skeleton root is gradually lowered (figure 9.9).

After the initial phase of constraints and joints control distribution is done, the hand task is set with highest priority. In order to animate the arm from the initial configuration to the desired one, the initial hand position and orientation are extracted and interpolated towards the goal hand position and orientation, generating several interpolated sub-goals. Interpola-tions can be simply linear, but should consider biomechanical properties. Inverse kinematics is then used to generate the final actor posture for each interpolated sub-goal.

After the reaching phase is completed, a follow movement might be required (figure 9.7). In this case, the hand keeps its orientation, and only its position is updated to follow the move-

15 ment of the object being manipulated. Figures 9.10 and 9.11 exemplify both reaching and mid-dle phases.

Fig. 9.8. Specific constraints are used to keep the actor’s spine as straight as possible

Fig. 9.9. When the position to reach with the hand is too low, additional constraints are used in order to obtain knee flexion. The images show, from left to right, the postures achieved when reaching each time lower positions

16

Fig. 9.10. The reaching phase of a button press manipulation. Note that the actor’s head is also con-trolled to look to the button, and the hand configuration is gradually interpolated towards the final button press shape

Fig. 9.11. The reaching and follow movements used to close a drawer. Note that during the “follow phase” (closing the drawer) the knee flexion is maintained

9.6 Case Studies

This section details how interaction plans can be actually coded. The focus is on explaining how different issues can be solved using simple scripted plans, and not to give a complete description of SOMOD instructions. The first case shows how simple interactions such as opening a drawer can be defined. The second example shows how concurrent object access can be handled when multiple actors want to interact with a same automatic door. And a final example shows how the graphical state machine editor can be used to simplify the definition of more complex interactions.

The examples shown here were generated with the Agents Common Environment (ACE) system [45], which integrates smart objects with higher-level behavioral control mo d-ules. For more information about ACE, and for higher-level animation examples obtained with ACE, please refer to the chapter Behavioral Animation of this book.

17 9.6.1 Opening a Drawer

Interaction plans are grouped as a set of behaviors, each one containing a list of instruc-tions, similarly to procedures of a program. The following code e xemplifies interactions of opening and closing a drawer, as showed in figures 9.9 and 9.11:

BEHAVIOR open_drawer

CheckVar var_open false

UserGoTo pos_front

UserDoGest gest_drawer

DoCmd cmd_open

SetVar var_open true

END

BEHAVIOR close_drawer

CheckVar var_open true

UserGoTo pos_front

UserDoGest gest_drawer

DoCmd cmd_close

SetVar var_open false

END

The instruction CheckVar determines if the behavior is available or not. For example, the behavior open_drawer is only available if the state variable var_open is false. In this way, at any time, actors can ask for a list of available interaction plans, i.e, available object behaviors according to the objects state.

Fig. 9.12. Several interactions similar to the opening drawer case: all are based on reaching a position and following an object’s movement

In the example, when an actor receives the plan open_drawer, it will execute each primi-tive instruction in the plan starting with the User keyword. That is, it will walk to the pro-posed position and then it will apply inverse kinematics to animate the actor to perform the

18 specified motion in the gesture gest_drawer. In this case, the motion includes a follow movement that is set to follow the movement of the drawer part. The drawer itself will be ani-mated by the smart object, according to the specified cmd_close parameters. At the end, the object state is changed, allowing the close_drawer behavior to be available. Note that both instructions, which are interpreted by the object and by the actor, are mixed in the same behavior.

This same kind of solution can be applied to all interactions consisted of reaching a place and then following an object’s movement. This is the case of interactions such as: pushing a button, opening the cover of a book, opening doors, etc (figure 9.12).

9.6.2 Multiple Actors Interaction

The following code exemplifies how state variables are used to synchronize multiple actors passing a same automatic door:

BEHAVIOR open

Private

IncVar var_passing 1 CheckVar var_passing 1 DoCmd opendoor

END

BEHAVIOR close

Private

IncVar var_passing -1 CheckVar var_passing 0 DoCmd cmd_close

END BEHAVIOR enter_l_r

Private

UserGoTo pos_l_in DoBh open

UserGoTo pos_r_out DoBh close END

BEHAVIOR enter_r_l

Private

UserGoTo pos_r_in DoBh open

UserGoTo pos_l_out DoBh close END

BEHAVIOR enter

UserGetClosest pos pos_l_in, pos_r_in

If pos==pos_l_in

DoBh enter_l_r

Else

DoBh enter_r_l

EndIf

END

Each time an actor desires to pass the door, it will interpret the behavior enter, that will give it the correct positions to pass the door without colliding with other actors. The behavior enter is the only one visible to the actor, as all others are declared private. It starts by de-ciding from which side the actor will enter, using the UserGetClosest instruction that

19 asks if the actor is closest to a position on the left side (pos_l_in), or on the right side (pos_r_in). Then, according to the result, the behavior to enter from the correct side is called.

Behaviors enter_l_r and enter_r_l simply: send the actor to an initial position, open the door, send the actor to the final posi tion on the other side, and close the door. But some more things are needed in order to cope with multiple actors. When modeling this smart object, several positions were created for each of four cases: going in from the left and right side, and going out from the left and right sides. Positions of a same case are given a same name, so that when the instruction UserGoTo is called, the object is able to keep track, among all defined positions with the same name, those that currently have no actor using it. Figure 9.3 illustrates this automatic door and the used positions. The figure shows four posi-tions for each case, which are associated to orientations and are represented as arrows. Note however that such strategy relies entirely on the correct definition of the positions, for a more general solution, actors should be also equipped with sensors to avoid colliding with other entities which are out of the smart object control.

Behaviors open and close are called to actually close or open the door. These behav-iors maintain a state variable that counts how many actors are currently passing the door (var_passing) to correctly decide if the door needs really to be open or closed. Remember that actors interpret the same script concurrently, so that all actors will ask to close the door, but only the last one will actually close it.

9.6.3 Complex Behaviors

Consider the case of modeling a two-stage lift. Such a lift is composed of many parts: doors, calling buttons, a cabin, and the lift itself. These parts need to have synchronized movements, and many details need to be taken into account in order to correctly control ac-tors interacting with the lift.

Similarly to the examples already explained, the modeling of the lift functionality is done in two phases. First, all basic behaviors are programmed, e.g., opening and closing doors, press-ing the calling button, and moving the lift from one stage to another. If the lift is to be used by multiple actors, then all corresponding details need to be taken into account. Then, a higher-level interaction of just entering the lift from the current floor to go to the other floor is coded using calls to the basic behaviors.

To simplify modeling behaviors of such complex objects, a state machine can be used permitting to define the states of the object as a whole, and the connections between the component behaviors.

Figure 9.13 shows a state machine example for the lift case. This state m achine has two global states: floor_1 and floor_2. When the lift is in floor_1, the only possible interaction is enter_12, that will call a private behavior which calls the full sequence of instructions: pressing the calling button, opening the door, entering inside, closing the door, move the cabin up, opening the other door, and going out.

In the lift behavior example of figure 9.13, there is a single interaction of entering the lift, which can be too long, giving no options to the actor during the interaction. Figure 9.14 shows another solution, which models the functionality of the lift by taking into account possible intermediate states. In this case, the actor needs to select, step by step, a sequence of interactions in order to take the lift to the other floor. As illustration, figure 9.15 shows some snapshots of the animation sequence of an actor entering the lift.

20

Fig. 9.13. A state machine for a two-stage lift functionality. The double circle state is the current state, and the rectangular boxes show the interaction needed to change of state. For example, to change from floor_1 to floor_2 state, interaction enter_12 is required

Fig. 9.14. A state machine considering intermediate states. The figure also shows behaviors associated with states, to be triggered whenever the object enters that state

With的用法全解

With的用法全解 with结构是许多英语复合结构中最常用的一种。学好它对学好复合宾语结构、不定式复合结构、动名词复合结构和独立主格结构均能起很重要的作用。本文就此的构成、特点及用法等作一较全面阐述，以帮助同学们掌握这一重要的语法知识。 一、 with结构的构成 它是由介词with或without+复合结构构成，复合结构作介词with或without的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二部分补足语由形容词、副词、介词短语、动词不定式或分词充当，分词可以是现在分词，也可以是过去分词。With结构构成方式如下： 1. with或without-名词/代词+形容词； 2. with或without-名词/代词+副词； 3. with或without-名词/代词+介词短语； 4. with或without-名词/代词 +动词不定式； 5. with或without-名词/代词 +分词。 下面分别举例： 1、 She came into the room，with her nose red because of cold.（with+名词+形容词，作伴随状语）

2、 With the meal over ， we all went home.（with+名词+副词，作时间状语） 3、The master was walking up and down with the ruler under his arm。（with+名词+介词短语，作伴随状语。） The teacher entered the classroom with a book in his hand. 4、He lay in the dark empty house，with not a man ，woman or child to say he was kind to me.（with+名词+不定式，作伴随状语）He could not finish it without me to help him.（without+代词 +不定式，作条件状语） 5、She fell asleep with the light burning.（with+名词+现在分词，作伴随状语） Without anything left in the with结构是许多英 语复合结构中最常用的一种。学好它对学好复合宾语结构、不定式复合结构、动名词复合结构和独立主格结构均能起很重要的作用。本文就此的构成、特点及用法等作一较全面阐述，以帮助同学们掌握这一重要的语法知识。 二、with结构的用法 with是介词，其意义颇多，一时难掌握。为帮助大家理清头绪，以教材中的句子为例，进行分类，并配以简单的解释。在句子中with结构多数充当状语，表示行为方式，伴随情况、时间、原因或条件（详见上述例句）。 1.带着，牵着…… (表动作特征)。如： Run with the kite like this.

with的复合结构和独立主格结构

1. with+宾语+形容词。比如：. The boy wore a shirt with the neck open, showing his bare chest. 那男孩儿穿着一件衬衫，颈部敞开，露出光光的胸膛。Don’t talk with your mouth full. 嘴里有食物时不要讲话。 2. with+宾语+副词。比如：She followed the guide with her head down. 她低着头，跟在导游之后。 What a lonely world it will be with you away. 你不在，多没劲儿呀！ 3. with+宾语+过去分词。比如：He was listening to the music with his eyes half closed. 他眼睛半闭着听音乐。She sat with her head bent. 她低着头坐着。 4. with+宾语+现在分词。比如：With winter coming, it’s time to buy warm clothes. 冬天到了，该买些保暖的衣服了。 He soon fell asleep with the light still burning. 他很快就睡着了，（可）灯还亮着。 5. with+宾语+介词短语。比如：He was asleep with his head on his arms. 他的头枕在臂膀上睡着了。 The young lady came in, with her two- year-old son in her arms. 那位年轻的女士进来了，怀里抱着两岁的孩子。 6. with+宾语+动词不定式。比如： With nothing to do in the afternoon, I went to see a film. 下午无事可做，我就去看了场电影。Sorry, I can’t go out with all these dishes to wash. 很抱歉，有这么多盘子要洗，我不能出去。 7. with+宾语+名词。比如： He died with his daughter yet a school-girl.他去逝时，女儿还是个小学生。 He lived a luxurious life, with his old father a beggar . 他过着奢侈的生活，而他的老父亲却沿街乞讨。(8)With so much work to do ,I can't go swimming with you. (9)She stood at the door,with her back towards us. (10)He entered the room,with his nose red with cold. with复合结构与分词做状语有啥区别 [ 标签：with, 复合结构, 分词状语] Ciro Ferrara 2009-10-18 16:17 主要是分词形式与主语的关系 满意答案好评率：100%

with复合结构专项练习96126

with复合结构专项练习（二） 一请选择最佳答案 1）With nothing_______to burn，the fire became weak and finally died out. A.leaving B.left C.leave D.to leave 2）The girl sat there quite silent and still with her eyes_______on the wall. A.fixing B.fixed C.to be fixing D.to be fixed 3）I live in the house with its door_________to the south.（这里with结构作定语） A.facing B.faces C.faced D.being faced 4）They pretended to be working hard all night with their lights____. A.burn B.burnt C.burning D.to burn 二：用with复合结构完成下列句子 1）_____________（有很多工作要做），I couldn't go to see the doctor. 2）She sat__________（低着头）。 3）The day was bright_____.（微风吹拂） 4）_________________________，（心存梦想）he went to Hollywood. 三把下列句子中的划线部分改写成with复合结构。 1）Because our lessons were over，we went to play football. _____________________________. 2）The children came running towards us and held some flowers in their hands. _____________________________. 3）My mother is ill，so I won't be able to go on holiday. _____________________________. 4）An exam will be held tomorrow，so I couldn't go to the cinema tonight. _____________________________.

with的用法大全

with的用法大全----四级专项训练with结构是许多英语复合结构中最常用的一种。学好它对学好复合宾语结构、不定式复合结构、动名词复合结构和独立主格结构均能起很重要的作用。本文就此的构成、特点及用法等作一较全面阐述，以帮助同学们掌握这一重要的语法知识。 一、 with结构的构成 它是由介词with或without+复合结构构成，复合结构作介词with或without的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二部分补足语由形容词、副词、介词短语、动词不定式或分词充当，分词可以是现在分词，也可以是过去分词。With结构构成方式如下： 1. with或without-名词/代词+形容词; 2. with或without-名词/代词+副词; 3. with或without-名词/代词+介词短语; 4. with或without-名词/代词+动词不定式; 5. with或without-名词/代词+分词。 下面分别举例：

1、 She came into the room，with her nose red because of cold.(with+名词+形容词，作伴随状语) 2、 With the meal over ， we all went home.(with+名词+副词，作时间状语) 3、The master was walking up and down with the ruler under his arm。(with+名词+介词短语，作伴随状语。) The teacher entered the classroom with a book in his hand. 4、He lay in the dark empty house，with not a man ，woman or child to say he was kind to me.(with+名词+不定式，作伴随状语) He could not finish it without me to help him.(without+代词 +不定式，作条件状语) 5、She fell asleep with the light burning.(with+名词+现在分词，作伴随状语) 6、Without anything left in the cupboard， she went out to get something to eat.(without+代词+过去分词，作为原因状语) 二、with结构的用法 在句子中with结构多数充当状语，表示行为方式，伴随情况、时间、原因或条件(详见上述例句)。

with的复合结构

基本用法 它是由介词with或without+复合结构构成，复合结构作介词with或without的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二部分补足语由形容词、副词、介词短语或非谓语动词充当 一、with或without+名词/代词+形容词 例句:1.I like to sleep with the windows open. 我喜欢把窗户开着睡觉。(伴随情况) 2.With the weather so close and stuffy, ten to one it'll rain presently. 大气这样闷，十之八九要下雨(原因状语) 二、with或without+名词/代词+副词 例句:1.She left the room with all the lights on. 她离开了房间，灯还亮着。(伴随情况) 2.The boy stood there with his head down. 这个男孩低头站在那儿。(伴随情况) 三、with或without+名词/代词+介词短语 例句:1.He walked into the dark street with a stick in his hand. 他走进黑暗的街道时手里拿着根棍子。(伴随情况) 2. With the children at school, we can't take our vacation when we want to. 由于孩子们在上学，所以当我们想度假时而不能去度假。(原因状语) 四、with或without+名词/代词+非谓语动词 1、with或without+名词/代词+动词不定式，此时，不定式表示将发生的动作。 例句: 1.With no one to talk to, John felt miserable. 由于没人可以说话的人，约翰感到很悲哀。(原因状语)

with用法归纳

with用法归纳 （1）“用……”表示使用工具，手段等。例如： ①We can walk with our legs and feet. 我们用腿脚行走。 ②He writes with a pencil. 他用铅笔写。 （2）“和……在一起”，表示伴随。例如： ①Can you go to a movie with me? 你能和我一起去看电影'>电影吗？ ②He often goes to the library with Jenny. 他常和詹妮一起去图书馆。 （3）“与……”。例如： I’d like to have a talk with you. 我很想和你说句话。 （4）“关于，对于”，表示一种关系或适应范围。例如： What’s wrong with your watch? 你的手表怎么了？ （5）“带有，具有”。例如： ①He’s a tall kid with short hair. 他是个长着一头短发的高个子小孩。 ②They have no money with them. 他们没带钱。 （6）“在……方面”。例如： Kate helps me with my English. 凯特帮我学英语。 （7）“随着，与……同时”。例如： With these words, he left the room. 说完这些话，他离开了房间。 [解题过程] with结构也称为with复合结构。是由with+复合宾语组成。常在句中做状语，表示谓语动作发生的伴随情况、时间、原因、方式等。其构成有下列几种情形： 1.with+名词(或代词)+现在分词 此时，现在分词和前面的名词或代词是逻辑上的主谓关系。 例如:1)With prices going up so fast, we can't afford luxuries. 由于物价上涨很快，我们买不起高档商品。（原因状语） 2)With the crowds cheering, they drove to the palace. 在人群的欢呼声中，他们驱车来到皇宫。（伴随情况） 2.with+名词(或代词)+过去分词 此时，过去分词和前面的名词或代词是逻辑上的动宾关系。

With的复合结构

With的复合结构 介词with without +宾语+宾语的补足语可以构成独立主格结构，上面讨论过的独立主格结构的几种情况在此结构中都能体现。 1. with+名词代词+形容词 He doesn’t like to sleep with the windows open. = He doesn’t like to sleep when the windows are open. He stood in the rain, with his clothes wet. = He stood in the rain, and his clothes were wet. With his father well-known, the boy didn’t want to study. 2. with+名词代词+副词 Our school looks even more beautiful with all the lights on. = Our school looks even more beautiful if when all the lights are on. The boy was walking, with his father ahead. = The boy was walking and his father was ahead. 3. with+名词代词+介词短语 He stood at the door, with a computer in his hand. He stood at the door, computer in hand. = He stood at the door, and a computer was in his hand. Vincent sat at the desk, with a pen in his mouth. Vincent sat at the desk, pen in mouth. = Vincent sat at the desk, and he had a pen in his mouth. 4. with+名词代词+动词的-ed形式 With his homework done, Peter went out to play. = When his homework was done, Peter went out to play. With the signal given, the train started. = After the signal was given, the train started. I wouldn’t dare go home without the job finished. = I wouldn’t dare go home because the job was not finish ed. 5. with+名词代词+动词的-ing形式 The girl hid her box without anyone knowing where it was. = The girl hid her box and no one knew where it was. Without anyone noticing, he slipped through the window. = When no one was noticing, he slipped through the window. 6. with+名词代词+动词不定式 The little boy looks sad, with so much homework to do. = The little boy looks sad because he has so much homework to do. with the window closed with the light on with a book in her hand with a cat lying in her arms with the problem solved with the new term to begin

with用法小结

with用法小结 一、with表拥有某物 Mary married a man with a lot of money . 马莉嫁给了一个有着很多钱的男人。 I often dream of a big house with a nice garden . 我经常梦想有一个带花园的大房子。 The old man lived with a little dog on the lonely island . 这个老人和一条小狗住在荒岛上。 二、with表用某种工具或手段 I cut the apple with a sharp knife . 我用一把锋利的刀削平果。 Tom drew the picture with a pencil . 汤母用铅笔画画。 三、with表人与人之间的协同关系 make friends with sb talk with sb quarrel with sb struggle with sb fight with sb play with sb work with sb cooperate with sb I have been friends with Tom for ten years since we worked with each other, and I have never quarreled with him . 自从我们一起工作以来，我和汤姆已经是十年的朋友了，我们从没有吵过架。 四、with 表原因或理由 John was in bed with high fever . 约翰因发烧卧床。 He jumped up with joy . 他因高兴跳起来。 Father is often excited with wine . 父亲常因白酒变的兴奋。 五、with 表“带来”，或“带有,具有”，在…身上，在…身边之意

with复合宾语的用法(20201118215048)

with+复合宾语的用法 一、with的复合结构的构成 二、所谓"with的复合结构”即是"with+复合宾语”也即"with +宾语+宾语补足语” 的结构。其中的宾语一般由名词充当（有时也可由代词充当）；而宾语补足语则是根据 具体的需要由形容词，副词、介词短语，分词短语（包括现在分词和过去分词）及不定式短语充当。下面结合例句就这一结构加以具体的说明。 三、1、with +宾语+形容词作宾补 四、①He slept well with all the windows open.（82 年高考题） 上面句子中形容词open作with的宾词all the windows的补足语， ②It' s impolite to talk with your mouth full of food. 形容词短语full of food 作宾补。Don't sleep with the window ope n in win ter 2、with+宾语+副词作宾补 with Joh n away, we have got more room. He was lying in bed with all his clothes on. ③Her baby is used to sleeping with the light on.句中的on 是副词，作宾语the light 的补足语。 ④The boy can t play with his father in.句中的副词in 作宾补。 3、with+宾语+介词短语。 we sat on the grass with our backs to the wall. his wife came dow n the stairs,with her baby in her arms. They stood with their arms round each other. With tears of joy in her eyes ,she saw her daughter married. ⑤She saw a brook with red flowers and green grass on both sides. 句中介词短语on both sides 作宾语red flowersandgreen grass 的宾补， ⑥There were rows of white houses with trees in front of them.，介词短语in front of them 作宾补。 4、with+宾词+分词（短语 这一结构中作宾补用的分词有两种，一是现在分词，二是过去分词，一般来说，当分词所表 示的动作跟其前面的宾语之间存在主动关系则用现在分词，若是被动关系，则用过去分词。 ⑦In parts of Asia you must not sit with your feet pointing at another person.（高一第十课），句中用现在分词pointing at…作宾语your feet的补足语，是因它们之间存在主动关系，或者说point 这一动作是your feet发出的。 All the after noon he worked with the door locked. She sat with her head bent. She did not an swer, with her eyes still fixed on the wall. The day was bright,with a fresh breeze（微风）blowing. I won't be able to go on holiday with my mother being ill. With win ter coming on ,it is time to buy warm clothes. He soon fell asleep with the light still bur ning. ⑧From space the earth looks like ahuge water covered globe,with a few patches of land stuk ing out above the water而在下面句子中因with的宾语跟其宾补之间存在被动关系，故用过去分词作宾补：

(完整版)with的复合结构用法及练习

with复合结构 一. with复合结构的常见形式 1.“with+名词/代词+介词短语”。 The man was walking on the street, with a book under his arm. 那人在街上走着，腋下夹着一本书。 2. “with+名词/代词+形容词”。 With the weather so close and stuffy, ten to one it’ll rain presently. 天气这么闷热，十之八九要下雨。 3. “with+名词/代词+副词”。 The square looks more beautiful than even with all the light on. 所有的灯亮起来，广场看起来更美。 4. “with+名词/代词+名词”。 He left home, with his wife a hopeless soul. 他走了，妻子十分伤心。 5. “with+名词/代词+done”。此结构过去分词和宾语是被动关系，表示动作已经完成。 With this problem solved, neomycin 1 is now in regular production. 随着这个问题的解决，新霉素一号现在已经正式产生。 6. “with+名词/代词+-ing分词”。此结构强调名词是-ing分词的动作的发出者或某动作、状态正在进行。 He felt more uneasy with the whole class staring at him. 全班同学看着他，他感到更不自然了。 7. “with+宾语+to do”。此结构中，不定式和宾语是被动关系，表示尚未发生的动作。 So in the afternoon, with nothing to do, I went on a round of the bookshops. 由于下午无事可做，我就去书店转了转。 二. with复合结构的句法功能 1. with 复合结构，在句中表状态或说明背景情况，常做伴随、方式、原因、条件等状语。With machinery to do all the work, they will soon have got in the crops. 由于所有的工作都是由机器进行，他们将很快收完庄稼。（原因状语） The boy always sleeps with his head on the arm. 这个孩子总是头枕着胳膊睡觉。（伴随状语）The soldier had him stand with his back to his father. 士兵要他背对着他父亲站着。（方式状语）With spring coming on, trees turn green. 春天到了，树变绿了。（时间状语） 2. with 复合结构可以作定语 Anyone with its eyes in his head can see it’s exactly like a rope. 任何一个头上长着眼睛的人都能看出它完全像一条绳子。 【高考链接】 1. ___two exams to worry about, I have to work really hard this weekend.（04北京） A. With B. Besides C. As for D. Because of 【解析】A。“with+宾语+不定式”作状语，表示原因。 2. It was a pity that the great writer died, ______his works unfinished. (04福建) A. for B. with C. from D.of 【解析】B。“with+宾语+过去分词”在句中作状语，表示状态。 3._____production up by 60%, the company has had another excellent year. (NMET) A. As B.For C. With D.Through 【解析】C。“with+宾语+副词”在句中作状语，表示程度。

With复合结构的用法小结

With复合结构的用法小结 with结构是许多英语复合结构中最常用的一种。学好它对学好复合宾语结构、不定式复合结构、动名词复合结构和独立主格结构均能起很重要的作用。本文就此的构成、特点及用法等作一较全面阐述，以帮助同学们掌握这一重要的语法知识。 一、with结构的构成 它是由介词with或without+复合结构构成，复合结构作介词with或without的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二 部分补足语由形容词、副词、介词短语、动词不定式或分词充当，分词可以是现在分词，也可以是过去分词。With结构构成方式如下： 1. with或without-名词/代词+形容词； 2. with或without-名词/代词+副词； 3. with或without-名词/代词+介词短语； 4. with或without-名词/代词+动词不定式； 5. with或without-名词/代词+分词。 下面分别举例： 1、She came into the room，with her nose red because of cold.（with+名词+形容词，作伴随状语） 2、With the meal over ，we all went home.（with+名词+副词，作时间状语） 3、The master was walking up and down with the ruler under his arm。（with+名词+介词短语，作伴随状语。）The teacher entered the classroom with a book in his hand. 4、He lay in the dark empty house，with not a man ，woman or child to say he was kind to me.（with+名词+不定式，作伴随状语）He could not finish it without me to help him.（without+代词+不定式，作条件状语） 5、She fell asleep with the light burning.（with+名词+现在分词，作伴随状语）Without anything left in the cupboard，shewent out to get something to eat.（without+代词+过去分词，作为原因状语） 二、with结构的用法 在句子中with结构多数充当状语，表示行为方式，伴随情况、时间、原因或条件（详见上述例句）。 With结构在句中也可以作定语。例如： 1.I like eating the mooncakes with eggs. 2.From space the earth looks like a huge water-covered globe with a few patches of land sticking out above the water. 3.A little boy with two of his front teeth missing ran into the house. 三、with结构的特点 1. with结构由介词with或without+复合结构构成。复合结构中第一部分与第二部分语法上是宾语和宾语补足语关系，而在逻辑上，却具有主谓关系，也就是说，可以用第一部分作主语，第二部分作谓语，构成一个句子。例如：With him taken care of，we felt quite relieved.（欣慰）→（He was taken good care of.）She fell asleep with the light burning. →（The light was burning.）With her hair gone，there could be no use for them. →（Her hair was gone.） 2. 在with结构中，第一部分为人称代词时，则该用宾格代词。例如：He could not finish it without me to help him. 四、几点说明： 1. with结构在句子中的位置：with 结构在句中作状语，表示时间、条件、原因时一般放在

山大复合材料结构与性能复习题参考答案.doc

1、简述构成复合材料的元素及其作用 复合材料由两种以上组分以及他们之间的界面组成。即构成复合材料的元素包括基体相、增强相、界面相。 基体相作用：具有支撑和保护增强相的作用。在复合材料受外加载荷时，基体相一剪切变形的方式起向增强相分配和传递载荷的作用，提高塑性变 形能力。 增强和作用：能够强化基体和的材料称为增强体，增强体在复合材料中是分散相, 在复合材料承受外加载荷时增强相主要起到承载载荷的作用。 界面相作用：界面相是使基体相和增强相彼此相连的过渡层。界面相具有一定厚度，在化学成分和力学性质上与基体相和增强相有明显区别。在复 合材料受外加载荷时能够起到传递载荷的作用。 2、简述复合材料的基本特点 (1)复合材料的性能具有可设计性 材料性能的可设计性是指通过改变材料的组分、结构、工艺方法和工艺参数来调节材料的性能。显然，复合材料中包含了诸多影响最终性能、可调节的因素，赋予了复合材料的性能可设计性以极大的自由度。 ⑵ 材料与构件制造的一致性 制造复合材料与制造构件往往是同步的，即复合材料与复合材料构架同时成型，在采用某种方法把增强体掺入基体成型复合材料的同时?，通常也就形成了复合材料的构件。 (3)叠加效应 叠加效应指的是依靠增强体与基体性能的登加，使复合材料获得一?种新的、独特而又优于个单元组分的性能，以实现预期的性能指标。 (4)复合材料的不足 复合材料的增强体和基体可供选择地范围有限；制备工艺复杂，性能存在波动、离散性；复合材料制品成本较高。

3、说明增强体在结构复合材料中的作用能够强化基体的材料称为增强体。增强体在复合材料中是分散相。复合材料中的增强体，按几何形状可分为颗 粒状、纤维状、薄片状和由纤维编制的三维立体结构。喑属性可分为有机增强体 和无机增强体。复合材料中最主要的增强体是纤维状的。对于结构复合材料，纤 维的主要作用是承载，纤维承受载荷的比例远大于基体；对于多功能复合材料， 纤维的主要作用是吸波、隐身、防热、耐磨、耐腐蚀和抗震等其中一种或多种， 同时为材料提供基本的结构性能；对于结构陶瓷复合材料，纤维的主要作用是增 加韧性。 4、说明纤维增强复合材料为何有最小纤维含量和最大纤维含量 在复合材料中，纤维体积含量是一个很重要的参数。纤维强度高，基体韧性好，若加入少量纤维，不仅起不到强化作用反而弱化，因为纤维在基体内相当于裂纹。所以存在最小纤维含量，即临界纤维含量。若纤维含量小于临界纤维量，则在受外载荷作用时，纤维首先断裂，同时基体会承受载荷，产生较大变形，是否断裂取决于基体强度。纤维量增加，强度下降。当纤维量大于临界纤维量时，纤维主要承受载荷。纤维量增加强度增加。总之，含量过低，不能充分发挥复合材料中增强材料的作用；含量过高，由于纤维和基体间不能形成一定厚度的界面过渡层, 无法承担基体对纤维的力传递，也不利于复合材料抗拉强度的提高。 5、如何设才计复合材料 材料设计是指根据对?材料性能的要求而进行的材料获得方法与工程途径的规划。复合材料设计是通过改变原材料体系、比例、配置和复合工艺类型及参数，来改变复合材料的性能，特别是是器有各向异性，从而适应在不同位置、不同方位和不同环境条件下的使用要求。复合材料的可设计性赋予了结构设计者更大的自由度，从而有可能设计出能够充分发掘与应用材料潜力的优化结构。复合材料制品的设计与研制步骤可以归纳如下： 1）通过论证明确对于材料的使用性能要求，确定设计目标 2）选择材料体系（增强体、基体） 3）确定组分比例、几何形态及增强体的配置 4）确定制备工艺方法及工艺参数

介词with的用法大全

介词with的用法大全 With是个介词，基本的意思是“用”，但它也可以协助构成一个极为多采多姿的句型，在句子中起两种作用；副词与形容词。 with在下列结构中起副词作用： 1.“with+宾语+现在分词或短语”，如： (1) This article deals with common social ills, with particular attention being paid to vandalism. 2.“with+宾语+过去分词或短语”，如： (2) With different techniques used, different results can be obtained. (3) The TV mechanic entered the factory with tools carried in both hands. 3.“with+宾语+形容词或短语”，如： (4) With so much water vapour present in the room, some iron-made utensils have become rusty easily. (5) Every night, Helen sleeps with all the windows open. 4.“with+宾语＋介词短语”，如： (6) With the school badge on his shirt, he looks all the more serious. (7) With the security guard near the gate no bad character could do any thing illegal. 5.“with+宾语＋副词虚词”，如： (8) You cannot leave the machine there with electric power on. (9) How can you lock the door with your guests in? 上面五种“with”结构的副词功能，相当普遍，尤其是在科技英语中。 接着谈“with”结构的形容词功能，有下列五种： 一、“with+宾语+现在分词或短语”，如： (10) The body with a constant force acting on it. moves at constant pace. (11) Can you see the huge box with a long handle attaching to it ? 二、“with+宾语+过去分词或短语” (12) Throw away the container with its cover sealed. (13) Atoms with the outer layer filled with electrons do not form compounds. 三、“with+宾语+形容词或短语”，如： (14) Put the documents in the filing container with all the drawers open.

with的复合结构用法小结

With 复合结构用法小结 “With + 复合结构”又称为“with结构”，在句中表状态或说明背景情况，常做伴随，方式，原因，条件等状语。具体结构如下： 1. With + 名词 + 介词短语? (1) He was asleep with his head on his arm. ? (2) The man came in with a whip in his hand. ? 在书面语中。上句也可以说成：The man came in, whip in hand. 2．with + 名词 + 形容词（强调名词的特性或状态）? (1)With the weather so close and stuffy, ten to one it'll rain presently.天气这么闷热，十之八九要下雨。? (2)He used to sleep with the windows open. 3. With + 名词 + 副词? (1)With John away, we've got more room. 约翰走了，我们的地方大了一些。? (2)The square looks more beautiful than ever with all the light on. 4. With + 名词 + -ed 分词（强调名词是 -ed分词动作的承受者或动作已经发生） ?(1)With this problem solved, neopenicillin 1 is now in regular production. 随着这个问题的解决，新霉素一号现在已正式生产。 ?(2)All the afternoon he worked with the door locked. 5. with + 名词 + -ing分词（强调名词是 -ing分词的动作的发出者或某动作，状态正在进行）? (1)I won’t be able to go on holiday with my mother being ill. ? (2)He felt more uneasy with the whole class staring at him. ? (3)With the field leveled and irrigation channels controlling the volume of water(水量), no such problem arose again. 6. with + 名词 + to do （不定式动作尚未发生）? (1)So in the afternoon, with nothing to do, I went on a round of the bookshops. 由于下午无事可做，我就去书店转了转。 ?(2)I can't go out with all these dishes to wash. 一、 with结构的构成 它是由介词with或without+复合结构构成，复合结构作介词with或without 的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二部分补足语由形容词、副词、介词短语、动词不定式或分词充当，分词可以是现在分词，也可以是过去分词。With结构构成方式如下： 1. with或without-名词/代词+形容词； 2. with或without-名词/代词+副词； 3. with或without-名词/代词+介词短语； 4. with或without-名词/代词 +动词不定式； 5. with或without-名词/代词 +分词。 下面分别举例： 1、 She came into the room，with her nose red because of cold.（with+名词+形容词，作伴随状语） 2、 With the meal over ， we all went home.（with+名词+副词，作时间状语） 3、The master was walking up and down with the ruler under his arm。（with+名词+介词短语，作伴随状语。） The teacher entered the classroom with a book in his hand. 4、He lay in the dark empty house，with not a man ，woman or child to say he was kind to me.（with+名词+不定式，作伴随状语） He could not finish it without me to help him.（without+代词 +不定式，作条件状语） 5、She fell asleep with the light burning.（with+名词+现在分词，作伴随状语） Without anything left in the with结构是许多英语复合结构中最