Systems and hybrid position force control processes of an industrial robot

A control process for an industrial robot, the robot comprising:

• a multi-axis robot arm comprising at least two electric actuators each apt to move one part of the robot arm with respect to another part of the robot arm about or along an axis of movement, each electric actuator being associated with a sensor configured for measuring an articular position of the corresponding actuator,
• an effector placed at an end of the robot arm,
• a robot control system comprising
• a central unit,
• an auxiliary unit configured for controlling power units, implementing an axis controller module comprising current control loops apt to generate setpoints for controlling the power units,
• power units apt to supply an appropriate electric current to the electric actuators,
• a data acquisition interface configured for receiving and sending the measurements from the sensors associated with the electric actuators,
• a communication link connecting the central unit, the auxiliary unit and the data acquisition interface, the communication link comprising a data bus,
• wherein the control process comprises:
• calculating, in modules implemented by the central unit, a time-dependent composite setpoint defining articular forces and velocities, according to target trajectory and to an operating mode,
• calculating, in the modules implemented by the central unit, a behavior matrix which describes a desired behavior of the robot arm, defining directions along which the calculated composite setpoint is to be applied,
• calculating, in an articular impedance controller module implemented by the auxiliary unit, an articular force setpoint for controlling the axis controller module according to said previously calculated composite setpoint and said behavior matrix,
• calculating, in the axis controller module implemented by the auxiliary unit, the control setpoints for the power units according to the articular force setpoint.