The GEC Tetrabot-a serial-parallel topology robot: control design aspects

GEC has developed a serial-parallel configuration robot called the `Tetrabot´ based on a geometric configuration which makes it possible to employ light but rigid moving parts. This leads to a six degree-of-freedom robot capable of very precise and rapid movements over a working volume of lm³. In the paper the prototype robot is analysed from the viewpoint of the control engineer. The initial design of the robot incorporates a control strategy based on the assumption that the motion of each of the six joints is decoupled. Linear PID controllers are used to control the position of each joint. The effectiveness of this approach is evaluated. Proposals for future work in refining the design of the Tetrabot control system are set out