In this paper, an alternative architecture of a robotic servo system, the Virtual Internal Model Following Control System, is proposed.
First, a trajectory tracking control problem of a robot arm in the working coordinate system is discussed and the control problem of a robot based on external information is formulated as a control problem of the error system, which is derived from the controlled robot arm linearized by nonlinear feedback and the desired trajectory. Then the virtual internal model following control system is proposed based on this formulation.
In the proposed control system, the Virtual Internal Model generates the Virtual Reference Signal, which is a modified reference signal based on the external information. This model is used to describe a control strategy of a robot in the control system for external information. The behavior of a robot toward the external information is controlled based on this model.
As an example of the proposed control architecture, mechanical impedance control problem is discussed. The experimental results illustrate the effectiveness of the proposed control system.