Compliance compensation in mechatronic systems

Compliance, or elasticity is present in many mechatronic systems, e.g. when the transmission of a movement is done using steel cables, belts or elastic shafts. Also, compliance can be present in some gearboxes, typically the harmonic drives, and in the links of a mechanical structure, e.g. a robot. This elasticity always limits the performances of the system and the issue of its reduction or compensation is of prime importance. In a mechatronic system, this compensation can also be done electronically in a cheaper way. In this paper, the basic principle of compliance compensation is presented. Depending on the application and on the sensor locations, various strategies can be used. The theoretical developments are supported by two real application examples, i.e. the wrist stiffening of a bilateral master-slave force reflecting servomanipulator and the stiffening of the actuators of a big robotic transporter