OPTIMAL CONTROL OF FLEXIBLE SPACE ROBOTS USING DIRECT COLLOCATION METHOD AND NONLINEAR PROGRAMMING

摘要

In this paper, the problem of optimal control of flexible space robots is considered and an efficient approach is proposed for solving it. The space robots are considered as mechanical manipulators having rigid and flexible links. The main duty of these robots is to translate a payload mass between two specified points. To derive dynamic model of these manipulators, their flexible links are assumed as a set of rigid links connected together. By adding strain potential energy to Lagrange equations, the flexible behaviour of flexible links is modeled with good accuracy. In present paper, the problem of optimal control of space robots is defined based on minimum time and minimum joint torque (minimum control effort) objective functions. Direct collocation method is used to solve these problems. This method converts the optimal control problem to a standard nonlinear programming problem. The proposed approach in this paper for modeling and solving optimal control problems of flexible robots can lead to optimal solution without any simplifications such as linearization and decoupling of state equations. This approach can be used for solving various optimal control problems in the fields of robotics and biomechanics.