Task-oriented structural design of manipulators based on operability evaluation

In this paper, a new method for designing the structure of manipulators based on evaluation of their adaptability to tasks is proposed. In the method, task directions are classified into three kinds of direction; operational direction, constrained direction and free direction. On each direction, condition of constraints by task environment is represented. The tasks are represented by a set of direction and condition of constraints. A new criterion, operability, is defined to quantify adaptability of manipulator to tasks, taking account of mobility in operational directions and immobility in constrained directions. The mobility and immobility is calculated based on the Jacobian matrix of manipulator. The operability evaluation method is implemented, and applied to structural design of manipulators, in which link parameters are optimized by the genetic algorithm. This system can derive suitable structure of manipulator to various tasks. The effectiveness of the system is shown concerning examples of welding tasks.