Abstract

In the biped Lucy pleated pneumatic artificial muscles are used instead of electrical motors to power the joints, because in an antagonistic set-up both the torque and the compliance are controllable. The muscles have also a high power to weight ratio and they can reduce impact effects. Interesting characteristics that can be exploited for legged robots. In this paper a control strategy is discussed where a torque control unit tracks a predefined trajectory and a compliance controller is used to reduce control efforts and energy consumption by fitting the compliance of the actuator to the natural compliance of the desired trajectory. The first part of this paper focusses on the torque control unit for the biped. The proposed control architecture consists of the joint trajectory generator and the joint trajectory tracking controller. The trajectory generator calculates trajectories represented by polynomials based on objective locomotion parameters, which are average forward speed, step length, step height and intermediate foot lift. The joint trajectory tracking controller is divided in three parts: a computed torque module, a delta-p unit and a bang-bang pressure controller. Results of the incorporation of this control architecture in the real biped Lucy are given. Several essential graphs showing tracking performance and pressure regulation are given and the effectiveness of the control algorithm is discussed. A second part of the paper focusses on the compliance controller which is experimentally tested on a one DOF pendulum. A mathematical formulation to exploit the natural dynamics with respect to different walking patterns for this purpose is explained. The experimental results show the effectiveness and importance of the adaptation strategy

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.