Intelligent tracking control of fixed-base and free-flying flexible space robots

Initially, tracking control of a fixed-base planar two-link rigid dynamics robot manipulator is simulated using inverse dynamics, linear quadratic regulator, fuzzy logic and linear quadratic Gaussian control strategies with a Jacobian transpose proportion-alderivative control law.; The inverse dynamics strategy model is extended to tracking control of a fixed-base planar two-link robot manipulator with flexible dynamics derived using dominant cantilever and pinned-pinned assumed modes of vibration. Adaptation of the control law and transverse link vibration suppression is achieved by a fuzzy logic system within the control strategy.; A heuristic design ratio is determined to select optimal fuzzy logic system controllers with a low number of membership functions, high tracking precision and fast execution time. Using the inverse flexible dynamics control strategy simulated tracking results are obtained for a fuzzy logic system with three, five, seven and nine triangular and Gaussian membership functions providing a combination of type and number of membership functions for optimal tracking control and execution time. An optimal fuzzy logic system design ratio of five is achieved with three triangular membership functions and an output scaling gain of fifteen.; Repetitive learning performance is compared for inverse rigid dynamics control vs. fuzzy logic control and inverse flexible dynamics control vs. fuzzy logic system adaptive control strategies. Control strategies using fuzzy logic induce responsiveness to repetitive learning; whereas the conventional inverse dynamics control strategies induce no response.; Nonmimmum phase behaviour of the flexible robot with dominant cantilever assumed mode dynamics is investigated to provide a method of achieving accurate end-effector tracking control in the presence of time delays and sensors noncollocated at alternate positions on the outboard link of a flexible robot manipulator. The effect of time-delayed control input is minimal compared to the overriding effect of fuzzy logic system adaptive control.; Hybrid control strategies are synthesized and simulated tracking results obtained for combinations of inverse flexible dynamics control with an extended Kalman filter or a fuzzy logic adaptive extended Kalman filter for noise filtering and a fuzzy logic system for vibration suppression. The effect of Kalman filtering is minimal while the fuzzy logic system has an overriding effect on diminishing transient vibration overshoot amplitudes at trajectory direction switches.; Finally, the end effector of a free-flying flexible space robot autonomously tracks a trajectory between two points in a space orbit using inverse flexible dynamics and fuzzy logic system adaptive control strategies for comparison. The robot autonomously tracks its end effector between initial and final positions in two-dimensional space while maintaining stability and station keeping the rigid spacecraft in its location in space. Simulated tracking results show inverse flexible dynamics control produces a significant drift and fails to reach its commanded final position. Fuzzy logic system adaptive control produces a more accurate direct trajectory with less drift and terminates closer to the commanded final position. But, sporadic high magnitude driving torque "spikes" occur, similar to the "bursting phenomenon" often encountered with adaptive control systems, but they are damped by the fuzzy logic system. The rigid spacecraft reactive translation and attitude change is minimal in each case but less so for fuzzy logic system adaptive control.