Real-time path planning for robot arms
Nigel William Balding · Durham e-Theses (Durham University) · 1987
This thesis presents two new methods for the automatic programming of robots, which were developed at the University of Durham.A model of the robot and its surroundings is held in the computer memory in a form which can be accessed quickly by the path generation algorithm.Information is fed to the computer which defines a task for the robot to perform.The path generation algorithm then calculates the coordinates for the movement of the robot, avoiding obstacles.Finally, the information is down-loaded into the robot control computer in its own language.An important feature of the method is the high speed of calculation and data transfer, which is designed for real-time operation.The world model is represented as a collection of spheres, some overlapping, and the robot is represented by connected cylinders.This simplified representation is the key to the speed of calculation of the path.Different criteria are used for the optimal path selection, such as minimisation of the overall time taken, the distance travelled and the joint rotation.Two path planning methods have been developed.The first incorporates a local method of trajectory calculation and the second uses a global method.Both methods are suitable for real-time applications, but they have different properties which can be exploited in different applications.The relative merits of the two methods are discussed.These methods provide an on-line, real-time capability for collision free path calculation in a flexible manufacturing environment.v S 10.3 Global pathfinding methods 10.4 The first method 137 10.5 The second method 10.6 Comparison of methods 10.7 Trajectories to suit calculations 10.8 Design of robot 10.9 Further work 144 10.10 A look into the furure 146 vi 11. References 12. Appendices A. Calculating the volumes of spheres modelling a unit cube B. To find robot paths between spheres 161 C. Mainrpf program listing