Rapid prototyping of a model-based control with friction compensation for a direct-drive robot

The development and application of the most recent model-based control schemes for robots require the investigation and solution of problems concerning various aspects, from the real-time (RT) simulation and control issues, to the necessity of determining a robot model suitable for control, and of experimentally testing the control performances. In this paper, different aspects are investigated for a planar, two-link direct-drive manipulator, with particular attention to the joint friction compensation within the control loop. A real-time architecture, based on the RT-Lab software by Opal-RT, is developed and used to carry out all the design phases, from the identification of the robot model, including joint friction torques, to the application of the inverse dynamics control schemes, with different solutions for the robot dynamics and friction compensation. The performances of such schemes are investigated executing various trajectories, suitable to check the, effectiveness of the friction compensation.