Computer Animation of Modular Robotic Systems, page 4

The elbow actuator is chosen from the 'add joint' option in the 'BUILD' menu. The module can be scaled by specifying the length as shown on the display. The length is specified by clicking on the box next to the word 'length' and then typing the length using the keyboard. After choosing the color, the module is addd to the robot model.

The inline roll module is the next chosen from the among the joints in the 'add joint' option under the 'BUILD' menu. After specifying the two lengths shown in the dialogue box and choosing the color, this module is added to the robot model. The conical link is chosen from among the links in the 'add link' option under the 'BUILD' menu. The length, input diameter, output diameter and color are specified. The Y translation of the output frame is chosen to be the same as the length so that the next module will be added onto the end of the link. Modules can be added until the graphical manipulator is complete.

Research Applications – The incorporation of modularity and reconfigurability in the computer animation of robotic systems facilitates the application of computer animation to many areas of robotics research. Animations of an extremely large class of robotics systems can be created by simply assembling together modules from a finite set of one, two and three degree of freedom joint modules and generic links. The creation of these animations is simplified to the extent that a model of the Robotics Research dual arm system with torso may be assembled in approximately ten minutes.

Computer animation is an effective method of visually representing kinematic data, such as might be generated by obstacle avoidance algorithms, redundant inverse kinematics routines and as the output from dynamic simulations. Modular and reconfigurable animation can be used in the development of serial, parallel, mobile and hybrid manipulators and is ideally suited to the development of modular and animation may be used to generate world model databases that include multiple robots and obstacles that may be fixed to a reference frame or may move about in the Obstacle avoidance refers to moving the robot while avoiding collisions with objects in the environment. The obstacles may include the robot itself, fixed objects in the environment, moving objects in the environment and also other robots that may be operating in the same workspace. The cost of an industrial robot colliding with an obstacle in the environment could be very high, both in terms of repair to the robot and the environment as well as the cost of lost productivity due to downtime. The results of a collision in a more sensitive environment, such as space, nuclear or military applications could be enormous. The cost of such collisions makes obstacle avoidance of fundamental importance when planning the robot's path. Computer animation of modular and reconfigurable robotic systems can be used as a tool in obstacle avoidance research. The same database that is used to generate the modular robot display can also be used as a database for the obstacle avoidance algorithms.

A redundant robot has more degrees of freedom than are necessary to specify the state of the end effector. Any robot with seven or more degrees of freedom is redundant because it only takes six parameters to specify the position and orientation of an object in three dimensional space. The extra degrees of freedom can be used to improve the performance of the system by allowing the end effector to reach the goal with many different joint paths. Different criteria can be used to determine which joint paths are best for a given situation . Walking machines, multi-fingered grippers and 'snake' manipulators are all examples of redundant robotic systems.

By definition, redundant robots have extra degrees of freedom. More computer programming time is necessary to generate the forward kinematics and visual simulation for these extra degrees of freedom. This time is significantly reduced by using computer animation based on a generalized modular and reconfigurable mechanical architecture. A robot with extra degrees of freedom simply has more joint modules and generic links. The many criteria that may be used by the inverse kinematics schemes may also be presented graphically by means of computer animation.

Dynamic modeling of robotic systems is an active area of robotics research . Dynamic modeling incorporates mass, compliance and damping to simulate the system response to joint forces and external loads. Computer animation can be used to display the results from these dynamic simulations. Dynamic models can be used to evaluate the performance of a robot as it performs a task. The condition number and singular values of the Jacobian matrix may also be incorporated into an evaluation procedure. The state of the inertia matrix has been used as a measure of the robot's dynamic ability. The dynamic model can be incorporated into feed-forward control algorithms. Feed-forward control incorporates the system dynamics into the control algorithm in order to synthesize the output. The dynamic model for the robotic system may be developed in terms of kinematic influence coefficients. The kinematic influence coefficients employ the geometry of the robot to relate the system's dynamic characteristics as they appear at any input to the system. Next Page ->