Trajectory Planning

Abstract

The previous chapters focused on mathematical modelling of mechanical manipulators in terms of kinematics, differential kinematics and statics, and dynamics. Before studying the problem of controlling a manipulation structure, it is worth presenting the main features of motion planning algorithms for the execution of specific manipulator tasks. The goal of trajectory planning is to generate the reference inputs to the motion control system which ensures that the manipulator executes the planned trajectories. The user typically specifies a number of parameters to describe the desired trajectory. Planning consists of generating a time sequence of the values attained by a polynomial function interpolating the desired trajectory. This chapter presents some techniques for trajectory generation both in the case when the initial and final point of the path are assigned (point-to-point motion), and in the case when a finite sequence of points are assigned along the path (path motion). First, the problem of trajectory planning in the joint space is considered, and then the basic concepts of trajectory planning in the operational space are illustrated. The chapter ends with the presentation of a technique for dynamic scaling a trajectory which allows adapting trajectory planning to manipulator dynamic characteristics.