Задани на лабораторные работы. ПРК / Professional Microsoft Robotics Developer Studio

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Chapter 7: Using Orchestration Services to Build a Simulation Scenario

{

// all the cones have been visited _endTime = DateTime.Now;

}

break;

}

After that, it checks whether all the cones have been touched. If so, the robot enters the Finished state. Otherwise, it returns to the Wander state to find more cones.

The Finished State

The Finished state simply causes the robot to spin around in wild celebration until you click the Reset button to try the scenario again:

case ModeType.Finished:

if (!driveCommandFailed)

yield return Arbiter.Choice( _drivePort.RotateDegrees(180, _rotateSpeed), delegate(DefaultUpdateResponseType response) { }, delegate(Fault f) { driveCommandFailed = true; }

);

break;

The Avoid Collision State

The only state that hasn’t been described yet is the AvoidCollision state. Right now, this state does the same thing regardless of where the obstacle lies. It would be a great improvement if the robot did more discovery to determine the direction to drive to actually avoid the obstacle, rather than blunder around:

case ModeType.AvoidCollision:

{

// back away

if (!driveCommandFailed)

yield return Arbiter.Choice( _drivePort.DriveDistance(-0.25, _driveSpeed), delegate(DefaultUpdateResponseType response) { }, delegate(Fault f) { driveCommandFailed = true; }

);

// turn left

if (!driveCommandFailed)

yield return Arbiter.Choice( _drivePort.RotateDegrees(90, _rotateSpeed), delegate(DefaultUpdateResponseType response) { }, delegate(Fault f) { driveCommandFailed = true; }

);

_state.CurrentMode = ModeType.Wander;

(continued)

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(continued)

// move forward

if (!driveCommandFailed)

yield return Arbiter.Choice( _drivePort.DriveDistance(1, _driveSpeed), delegate(DefaultUpdateResponseType response) { }, delegate(Fault f) { driveCommandFailed = true; }

);

break;

}

As you can see from the implementation, when the robot detects an impending collision, it backs up a quarter meter, turns 90 degrees to the left, changes to Wander mode, and then drives forward one meter.

Add the state implementations just discussed to your code, along with the GetHappiness method and its associated variables, and your SimMagellan service is complete.

Using the SimMagellan Service

Once you click Reset and Start, the service runs itself. You will probably have to move the MainCamera around a bit to keep the Corobot in view, and you’ll definitely want to be watching the SimMagellan user interface form to see the results of the image processing and the current state of the robot. The elapsed time gives you a good measure of your algorithm’s efficiency, although the same algorithm can have radically different execution times as a result of very small variations in the robot’s behavior. Each time you enhance the robot behavior, measure the elapsed time of a few runs to determine the amount of improvement you have achieved.

Don’t forget that you can use the Simulation Editor to select the Corobot entity and move it around in the environment. This can come in handy if it happens to hit a wall on the edge and flip over or if you just want to see how it handles a particular approach to a cone.

Future Directions

There are several things you can do with this simulation scenario to make it more like the actual SRS Robo-Magellan competition. For one thing, very few robot drives can report back on their actual position in the world. You should implement a simulated GPS entity and associated service that returns the position of the robot in latitude and longitude. Such a simulated service should probably also provide a way to model areas of poor reception in the world so that the navigation algorithm can handle these properly.

Another improvement to this simulation would be to change the happiness function to make the robot traverse the cones in a particular order. In the current simulation, the order in which the robot visits the cones is unimportant. One simple way to make the obstacle avoidance more efficient is to add waypoints with a negative happiness to the list each time an obstacle is encountered. This would keep the robot from moving toward an area where there is a known obstacle.

Finally, the obstacles in the environment are currently fairly simple. It is fairly easy to reconfigure the environment in the Referee service or to even have several canned environments that can be easily selected. A good navigation algorithm should be able to handle a variety of environments.

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Chapter 7: Using Orchestration Services to Build a Simulation Scenario

Summary

Congratulations! Between this chapter and the last one, you have covered quite a bit of territory, not to mention nearly 3500 lines of code.

In this chapter, you built on the entities and services defined in the last chapter to create a complete scenario. A Referee service initialized the environment with trigger cones, barriers, and a single Corobot. Finally, you defined the Robo-Magellan orchestration service, complete with a Windows Forms user interface and a robot behavior model sufficient to navigate the course.

Having conquered the world of wheeled robots for the time being, you’ll now move on to robotic arms and articulated robots in the next chapter.

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Part II: Simulations

methods. This is the object you must use when interacting with the physics engine. It is simple to convert a Joint object to a PhysicsJoint object and back again, as you’ll see in the example code in this chapter.

The Joint Frame

Before you look in detail at the JointProperties class, it is important to understand the joint frame. A frame is a set of three axes that represent one coordinate system relative to another. This concept should be familiar to those readers who have worked with computer graphics. In a typical graphics scene, each object has its own frame relative to the world coordinates that determines its position and orientation. In graphics coordinates, we usually label the three axes in a frame as the X axis, the Y axis, and the Z axis.

Frames are used to specify the orientation of a joint as well. The three axes in a joint frame are called the local axis, the normal axis, and the binormal axis, as shown in Figure 8-1.

Normal Axis

Swing 1

Local Axis

Binormal Axis

Twist

Swing 2

Figure 8-1

The joint frame follows the right-handed convention, meaning positive rotations around each axis are in the direction the fingers on your right hand curl when your thumb is pointed along the positive axis. The frame may be completely defined by specifying only two of the axes because the axes are always at right angles to each other and the third axis can be constructed by taking the cross product of the other two.

The joint names each angular degree of freedom (DOF), as shown in Figure 8-1. The Twist DOF is associated with rotations around the local axis, the Swing1 DOF is associated with rotations around the normal axis, and the Swing2 DOF is associated with rotations around the binormal axis.

Joint Properties

The joint properties define how the joint behaves and how it attaches to the entities it joins. A joint may contain a reference to a JointAngularProperties class to unlock one or more angular degrees of freedom. It may also contain a reference to a JointLinearProperties class to unlock one or more

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Chapter 8: Simulating Articulated Entities

linear degrees of freedom. It must always contain a two-element array of EntityJointConnector references to specify how it attaches to each entity.

The following sections describe the various members of the JointAngularProperties class, the

JointLinearProperties class, the EntityJointConnector class, and other associated classes. These properties are explored in more detail in sample code following the descriptions.

JointAngularProperties

The following table lists the members of the JointAngularProperties class:

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JointLimitProperties

The following table lists the members of the JointLimitProperties class:

JointDriveProperties

The following table lists the members of the JointDriveProperties class:

JointLinearProperties

The following table lists the members of the JointLinearProperties class:

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EntityJointConnector

The joint is anchored to each entity at a point and orientation specified by an EntityJointConnector, which has the following members:

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JointProperties

The following table lists the members of the JointProperties class:

A Joint TestBench

The best way to gain a good understanding of these various joint properties is to build a sample program that creates a variety of joints with various properties to see how they work.

Open the Chapter 8 solution in ProMRDS\Chapter8 and then open the TestBench.cs file in the TestBench project. This TestBench service is a basic simulation service much like Simulation Tutorial 1

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