INTEGRATED ADAPTIVE-CONTROL FOR SPACE MANIPULATORS

The paper focuses on indirect adaptive control of space robot manipula tors when maneuvering payloads with imperfectly known mechanical param eters. The objective is to estimate system mechanical parameters durin g the maneuver itself. The system bodies are rigid, and are concatenat ed by ideal, rotational joints. Existing adaptive control laws are inv estigated in an application to a rotating. single-degree-of-freedom bo dy. Even in this simple case, and more so in general multibody cases, improvements in adaptive control laws are found to be needed. A new ad aptive control law is developed which is applicable to general, rigid, multibody systems. It is based on the reinterpretation of the system dynamic equations as a measurement equation. The adaptive control law is of the ''integrated'' type, i.e. the estimator part is used to esti mate the integrated influence of the system mechanical parameters, rat her than the parameters themselves. The controller part (the control l aw proper) is of the ''certainty equivalence'' type. For the single-de gree-of-freedom case, the system formal solution is presented. Then th e parameter estimation process and the control law are separately anal yzed to show that the control system output error is globally asymptot ically stable, as well as the parameter error, provided the external c ommand input satisfies a persistent excitation condition. In one numer ical example it is shown how a two-armed, nine-degree-of-freedom space robot can be controlled almost as if the mechanical parameters were p erfectly known. Copyright (C) 1996 Elsevier Science Ltd