Cartesian-Space Time Delay Compensation in Leader-Follower Coordination of Two Manipulators using Periodic Time Functions

Different approaches in multi-manipulator control can be classified into those which adopt a leader-follower operation and those which use indistinguished control. Although leader-follower coordination is more efficient to implement, its performance is more susceptible to the leader arm controller performance. In this paper coordinated control of two manipulators carrying a common object using discrete position feedback is developed and tested using a multi-processor architecture and two PUMA robots. Since the research is experimental, leader-follower coordination is used because of its computational efficiency. Computation and other timing delays incur the loss of two sampling intervals. This is where a class of predictive filters is designed to compensate for these delays. These filters are developed using the delayed follower arm desired positions to estimate a model of its desired trajectory using periodic functions of time. Both exact and least squares spline fitting are carried out and the performances of the resulting estimators are compared.