Requirement derivation method for a legged robot with series-elastic actuators
Resumo
In this work we propose a new methodology for requirement derivation of the dynamical requirements of a series elastic actuator applied to a legged robot. The leg model consists of a mechanism composed of three links – representing the thigh, the shin and the foot – and two Series Elastics Actuators (SEA) – representing the knee and ankle. The stance phase of a running gait is modeled according to the Spring Loaded Inverted Pendulum (SLIP) method. To make sure that sufficient extent of running patterns is covered, the SLIP parameters are sampled inside a predefined range using the Improved Distributed Hypercube Sampling method. The number of samples used in this study is selected through a convergence test. The leg performance is then studied through a comparison between the CoM trajectory obtained simulating the mechanism with ideal actuators on its joints and with SEAs. A closed loop Impedance Controller is used to calculate the torque required by each joint that allows the system to behave as a spring, thus mimicking the spring-like behavior of the leg during the SLIP movement. The SEAs are modeled by a parametric transfer function that is also presented in this work. To the best of our knowledge, this work is the first to propose a method that accounts for the performance of this task execution.
Referências
Calanca, A., Muradore, R., Fiorini, P.: Impedance control of series elastic actuators: Passivity and acceleration-based control. Mechatronics 47, 37–48 (Nov 2017). https://doi.org/10.1016/j.mechatronics.2017.08.010
Craig, J.J.: Introduction to robotics: mechanics and control. Pearson/Prentice Hall, Upper Saddle River, N.J, 3rd ed edn. (2005).
Ferris, D.P., Louie, M., Farley, C.T.: Running in the real world: adjusting leg stiffness for different surfaces. Proceedings of the Royal Society B: Biological Sciences 265(1400), 989–994 (Jun 1998). https://doi.org/10.1098/rspb.1998.0388
Heglund, N.C., Taylor, C.R.: Speed, stride frequency and energy cost per stride: how do they change with body size and gait? The Journal of Experimental Biology 138, 301–318 (Sep 1988).
Hogan, N.: Impedance Control: An Approach to Manipulation. In: 1984 American Control Conference. pp. 304–313. IEEE, San Diego, CA, USA (Jul 1984). https://doi.org/10.23919/ACC.1984.4788393
Hogan, N.: Impedance Control: An Approach to Manipulation: Part I – Theory. Journal of Dynamic Systems, Measurement, and Control 107(1), 1 (1985). https://doi.org/10.1115/1.3140702
Hogan, N.: Impedance Control: An Approach to Manipulation: Part II – Implementation. Journal of Dynamic Systems, Measurement, and Control 107(1), 8 (1985). https://doi.org/10.1115/1.3140713
Hutter, M.: StarlETH & Co.: Design and control of legged robots with compliant actuation. PhD Thesis, ETH Zurich (2013). https://doi.org/10.3929/ethza-009915229
McMahon, T.A., Cheng, G.C.: The mechanics of running: How does stiffness couple with speed? Journal of Biomechanics 23, 65–78 (Jan 1990). https://doi.org/10.1016/0021-9290(90)90042-2
Pratt, G., Williamson, M.: Series elastic actuators. In: Proceedings 1995 IEEE/RSJ International Conference on Intelligent Robots and Systems. Human Robot Interaction and Cooperative Robots. vol. 1, pp. 399–406. IEEE Comput. Soc. Press, Pittsburgh, PA, USA (1995). https://doi.org/10.1109/IROS.1995.525827
Robinson, D.W.: Design and Analysis of Series Elasticity in Closed-loop Actuator Force Control by. PhD Thesis, Massachusetts Institute of Technology (2000).
Schwind, W., Koditschek, D.: Characterization of monoped equilibrium gaits. In: Proceedings of International Conference on Robotics and Automation. vol. 3, pp. 1986–1992. IEEE, Albuquerque, NM, USA (1997). https://doi.org/10.1109/ROBOT.1997.619161
Semini, C.: HyQ Design and Development of a Hydraulically Actuated Quadruped Robot. Thesis (Ph.D.), Italian Institute of Technology, University of Genoa (2010).
Seok, S., Wang, A., Meng Yee Chuah, Otten, D., Lang, J., Kim, S.: Design principles for highly efficient quadrupeds and implementation on the MIT Cheetah robot. In: 2013 IEEE International Conference on Robotics and Automation. pp. 3307–3312. IEEE, Karlsruhe, Germany (May 2013). https://doi.org/10.1109/ICRA.2013.6631038
Silder, A., Besier, T., Delp, S.L.: Running with a load increases leg stiffness. Journal of Biomechanics 48(6), 1003–1008 (Apr 2015). https://doi.org/10.1016/j.jbiomech.2015.01.051
Tedrake, R., the Drake Development Team: Drake: Model-based design and verification for robotics (2019), https://drake.mit.edu.
Yu, H., Gao, H., Fan, Z., Deng, Z., Zhang, L.: Dual-slip model based galloping gait control for quadruped robot: A task-space formulation. In: 2017 American Control Conference (ACC). pp. 191–197. IEEE, Seattle, WA (May 2017).
