Historical perspectives and state of the art in joint force sensory feedback control of manipulation robots

Abstract

SUMMARYThe application of the joint force sensory feedback in both the gross and fine motion control of manipulation robots is considered in the paper. One of the objectives of the paper is to give a historical overview how the idea of the joint force sensory feedback has appeared and developed in the past two decades. The control schemes, which include joint torque sensory feedback, are surveyed in the paper. The main advantages of this approach are discussed: the joint torque feedback offers an elegant way to compensate for the effects of the robot dynamics without real time computation of the robot dynamics, the control schemes are robust in respect of parameter variations. Various problems regarding design and implementation of joint torque sensor are also considered. Special emphasis is given to the application of this approach in hybrid position/force control schemes.

A Modular and High-Precision Motion Control System With an Integrated Motor

“…The application of joint-torque sensory feedback (JTF) in robot control to suppress the effect of load torque on a motion servo controller has been proposed [8], [9], [15], [16]. This control scheme, unlike the model-based controllers, does not require the dynamic model of the load, i.e., the links of a manipulator.…”

“…A survey of JTF can be found in [16]. In summary, the main advantages claimed for JTF [8], [15] are as follows.…”

“…3) The control system can completely reject external force disturbances applied on the load. In robotics applications, joint torque sensing can be used to eliminate completely the effect of link dynamics if the manipulator's joint are endowed with joint torque sensor device [8], [9], [15], [16]. The system dynamics are determined completely by the motion of the motor rotors in the Cartesian space that is not detectable by the torque sensors.…”

Joint Torque Sensory in Robotics

“…However, the performance may be compromised in these control approaches. Alternatively, the dynamic control of manipulators can be performed by using jointtorque sensory feedback without the need for modelling link dynamics (Hashimoto, 1989b;Kosuge et al, 1990;Stokic and Vukobratovic, 1993;Aghili et al, 2001;Aghili and Namvar, 2006). Such a controller can achieve robust performance against variation of link dynamics and rejection of external force disturbances at the expense of using additional sensors.…”

“…Hashimoto (Hashimoto, 1989b) applied this technique to a harmonic-drive actuator where the deformation of flex-splines are used to measure joint-torques. A survey of JTF can be found in (Stokic and Vukobratovic, 1993). In summary, the main advantages claimed for JTF are:…”