Model-free Friction Observers for Flexible Joint Robots with Torque Measurements
This addresses friction compensation for flexible joint robots, offering a model-free approach that avoids overcompensation, but it is incremental as it builds on existing observer methods.
The paper tackled friction compensation in flexible joint robots without requiring a friction model, achieving asymptotic stability and passivity by feeding back a nominal motor-side signal instead of the measured one, with validation through simulations and experiments.
This paper tackles a friction compensation problem without using a friction model. The unique feature of the proposed friction observer is that the nominal motor-side signal is fed back into the controller instead of the measured signal. By doing so, asymptotic stability and passivity of the controller are maintained. Another advantage of the proposed observer is that it provides a clear understanding for the stiction compensation which is hard to be captured in model-free approaches. This allows to design observers that do not overcompensate for the stiction. The proposed scheme is validated through simulations and experiments.