Abstract
Classic control theory applied to compliant and soft robots generally involves an increment of computation that has no equivalent in biology. To tackle this, morphological computation describes a theoretical framework that takes advantage of the computational capabilities of physical bodies. However, concrete applications in robotic locomotion control are still rare. Also, the trade-off between compliance and the capacity of a physical body to facilitate its own control has not been thoroughly studied in a real locomotion task. In this paper, we address these two problems on the state-of-the-art hydraulic robot HyQ. An end-to-end neural network is trained to control HyQ’s joints positions and velocities using only Ground Reaction Forces. Our simulations and experiments demonstrate better controllability using less memory and computational resources when increasing compliance. However, we show empirically that this effect cannot be attributed to the ability of the body to perform intrinsic computation. It invites to give an increased emphasis on compliance and co-design of the controller and the robot to facilitate attempts in machine learning locomotion.
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Barasuol, V., Buchli, J., Semini, C., Frigerio, M., de Pieri, E. R. & Caldwell, D. G. (2012). A reactive controller framework for quadrupedal locomotion on challenging terrain. In IEEE International Conference on Robotics and Automation, ICRA 2012 (pp. 2554–2561).
Bledt, G., Powell, M. J., Katz, B., Carlo, J. D., Wensing, P. M. & Kim, S. (2018). MIT cheetah 3: Design and control of a robust, dynamic quadruped robot. In IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2018 (pp. 2245–2252).
Boaventura, T., Focchi, M., Frigerio, M., Buchli, J., Semini, C., Medrano-Cerda, G. A. & Caldwell, D. G. (2012). On the role of load motion compensation in high-performance force control. In IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2012 (pp. 4066–4071).
Boaventura, T., Medrano-Cerda, G. A., Semini, C., Buchli, J. & Caldwell, D. G. (2013). Stability and performance of the compliance controller of the quadruped robot hyq. In IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2013 (pp. 1458–1464).
Boaventura, T., Semini, C., Buchli, J., Frigerio, M., Focchi, M. & Caldwell, D. G. (2012). Dynamic torque control of a hydraulic quadruped robot. In IEEE International Conference on Robotics and Automation, ICRA 2012 (pp. 1889–1894).
Brooks, R. A. (1991). Intelligence without representation. Artificial Intelligence, 47(1–3), 139–159.
Calisti, M., Picardi, G., & Laschi, C. (2017). Fundamentals of soft robot locomotion. Journal of the Royal Society Interface, 14(130), 20170101.
Caluwaerts, K., D’Haene, M., Verstraeten, D., & Schrauwen, B. (2013). Locomotion without a brain: Physical reservoir computing in tensegrity structures. Artificial Life, 19(1), 35–66.
Carbajal, J. P. (2012). Harnessing nonlinearities: Generating behavior from natural dynamics (Unpublished doctoral dissertation). Mathematisch-naturwissenschaftlichen Fakultät: Universität Zürich.
Dambre, J., Verstraeten, D., Schrauwen, B., & Massar, S. (2012). Information processing capacity of dynamical systems. Scientific Reports, 2, 514.
Degrave, J., Caluwaerts, K., Dambre, J. & wyffels, F. (2015). Developing an embodied gait on a compliant quadrupedal robot. In IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2015 (pp. 4486–4491).
Degrave, J., Cauwenbergh, R. V., wyffels, F., Waegeman, T. & Schrauwen, B. (2013). Terrain classification for a quadruped robot. In 12th International Conference on Machine Learning and Applications, ICMLA 2013 (pp. 185–190).
Dzeladini, F., Van Den Kieboom, J., & Ijspeert, A. (2014). The contribution of a central pattern generator in a reflex-based neuromuscular model. Frontiers in Human Neuroscience, 8, 371.
Eder, M., Hisch, F., & Hauser, H. (2018). Morphological computation-based control of a modular, pneumatically driven, soft robotic arm. Advanced Robotics, 32(7), 375–385.
Ekeberg, O., & Pearson, K. G. (2005). Computer simulation of stepping in the hind legs of the cat: an examination of mechanisms regulating the stance-to-swing transition. Journal of Neurophysiology, 94(6), 4256–68.
Eschenauer, H., Koski, J., & Osyczka, A. (2012). Multicriteria Design Optimization: Procedures and Applications. Berlin: Springer Science and Business Media.
Focchi, M., Boaventura, T., Semini, C., Frigerio, M., Buchli, J. & Caldwell, D. G. (2012). Torque-control based compliant actuation of a quadruped robot. In 12th IEEE International Workshop on Advanced Motion Control, AMC 2012 (pp. 1–6).
Focchi, M., Orsolino, R., Camurri, M., Barasuol, V., Mastalli, C., Caldwell, D. G., & Semini, C. (2020). Heuristic planning for rough terrain locomotion in presence of external disturbances and variable perception quality. In Advances in robotics research: From lab to market: ECHORD$++$: Robotic science supporting innovation (pp. 165–209). Springer.
Füchslin, R. M., Dzyakanchuk, A., Flumini, D., Hauser, H., Hunt, K. J., Luchsinger, R. H., et al. (2013). Morphological computation and morphological control: Steps toward a formal theory and applications. Artificial Life, 19(1), 9–34.
Galloway, K. C., Clark, J. E., Yim, M. & Koditschek, D. E. (2011). Experimental investigations into the role of passive variable compliant legs for dynamic robotic locomotion. In IEEE International Conference on Robotics and Automation, ICRA 2011 (pp. 1243–1249).
Geyer, H., & Herr, H. (2010). A Muscle-reflex model that encodes principles of legged mechanics produces human walking dynamics and muscle activities. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 18(3), 263–273.
Hauser, H., Ijspeert, A. J., Füchslin, R. M., Pfeifer, R., & Maass, W. (2011). Towards a theoretical foundation for morphological computation with compliant bodies. Biological Cybernetics, 105(5–6), 355–370.
Heijmink, E., Radulescu, A., Ponton, B., Barasuol, V., Caldwell, D. G. & Semini, C. (2017). Learning optimal gait parameters and impedance profiles for legged locomotion. In 17th IEEE-RAS International Conference on Humanoid Robotics, Humanoids 2017 (pp. 339–346).
Hoffmann, M. & Müller, V. C. (2017). Simple or complex bodies? trade-offs in exploiting body morphology for control. In Representation and Reality in Humans, Other Living Organisms and Intelligent Machines (pp. 335–345). Springer.
Hoffmann, M., & Simanek, J. (2017). The merits of passive compliant joints in legged locomotion: Fast learning, superior energy efficiency and versatile sensing in a quadruped robot. Journal of Bionic Engineering, 14(1), 1–14.
Hogan, N. (1984). Impedance control: An approach to manipulation. In 1984 American Control Conference (pp. 304–313).
Huang, G. B., Zhu, Q. Y., & Siew, C. K. (2004). Extreme learning machine: A new learning scheme of feedforward neural networks. Neural Networks, 2, 985–990.
Hutter, M., Gehring, C., Jud, D., Lauber, A., Bellicoso, C. D., Tsounis, V. Höpflinger, M. A. (2016). Anymal: A highly mobile and dynamic quadrupedal robot. In IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2016 (pp. 38–44).
Hwangbo, J., Lee. J., Dosovitskiy, A., Bellicoso, D., Tsounis, V., Koltun, V., & Hutter, M. (2019). Learning agile and dynamic motor skills for legged robots. Science Robotics, 4(26), eaau5872.
Iida, F., & Pfeifer, R. (2004). Cheap rapid locomotion of a quadruped robot: Self-stabilization of bounding gait. Intelligent Autonomous Systems, 8, 642–649.
Kashiri, N., Abate, A., Abram, S. J., Albu-Schaffer, A., Clary, P. J., Daley, M., et al. (2018). An overview on principles for energy efficient robot locomotion. Frontiers in Robotics and AI, 5, 129.
Magana, O. A. V., Barasuol, V., Camurri, M., Franceschi, L., Focchi, M., Pontil, M., et al. (2019). Fast and continuous foothold adaptation for dynamic locomotion through cnns. IEEE Robotics and Automation Letters, 4, 2140–2147.
Manoonpong, P., Geng, T., Kulvicius, T., Porr, B., & Wörgötter, F. (2007). Adaptive, fast walking in a biped robot under neuronal control and learning. PLoS Computational Biology, 3(7), e134.
McMahon, T. A. (1985). The role of compliance in mammalian running gaits. Journal of Experimental Biology, 115(1), 263–282.
Müller, V. C., & Hoffmann, M. (2017). What is morphological computation? On how the body contributes to cognition and control. Artificial Life, 23(1), 1–24.
Murai, A. & Yamane, K. (2011). A neuromuscular locomotion controller that realizes human-like responses to unexpected disturbances. In IEEE International Conference on Robotics and Automation, ICRA 2011 (pp. 1997–2002).
Nakajima, K., Hauser, H., Kang, R., Guglielmino, E., Caldwell, D. G., & Pfeifer, R. (2013). A soft body as a reservoir: Case studies in a dynamic model of octopus-inspired soft robotic arm. Frontiers in Computational Neuroscience, 7, 91.
Papadopoulos, D. & Buehler, M. (2000). Stable running in a quadruped robot with compliant legs. In IEEE International Conference on Robotics and Automation, ICRA 2000 (pp. 444–449).
Pfeifer, R., & Bongard, J. (2007). How the Body Shapes the Way We Think: A New View on Intelligence. Cambridge: MIT Press.
Raibert, M., Nelson, K. B. G., & Playter, R. (2008). Bigdog, the rough-terrain quadruped robot. IFAC Proceedings Volumes, 41(2), 10822–10825.
Rückert, E. A., & Neumann, G. (2013). Stochastic optimal control methods for investigating the power of morphological computation. Artificial Life, 19(1), 115–131.
Semini, C., Barasuol, V., Boaventura, T., Frigerio, M., Focchi, M., Caldwell, D. G., et al. (2015). Towards versatile legged robots through active impedance control. The Interational Journal of Robotics Research, 34(7), 1003–1020.
Semini, C., Tsagarakis, N. G., Guglielmino, E., Focchi, M., Cannella, F., & Caldwell, D. G. (2011). Design of hyq-a hydraulically and electrically actuated quadruped robot. Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering, 225(6), 831–849.
Seok, S., Wang, A., Chuah, M. Y., Hyun, D. J., Lee, J., Otten, D. M., et al. (2014). Design principles for energy-efficient legged locomotion and implementation on the mit cheetah robot. IEEE/ASME Transactions on Mechatronics, 20(3), 1117–1129.
Seok, S., Wang, A., Otten, D. & Kim, S. (2012). Actuator design for high force proprioceptive control in fast legged locomotion. In IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2012 (pp. 1970–1975).
Siciliano, B., & Khatib, O. (Eds.). (2008). Springer Handbook of Robotics. Berlin: Springer.
Spröwitz, A., Tuleu, A., Ajallooeian, M., Vespignani, M., Möckel, R., Eckert, P., et al. (2018). Oncilla robot: A versatile open-source quadruped research robot with compliant pantograph legs. Frontiers in Robotics and AI, 5, 67.
Spröwitz, A., Tuleu, A., Vespignani, M., Ajallooeian, M., Badri, E., & Ijspeert, A. J. (2013). Towards dynamic trot gait locomotion: Design, control, and experiments with cheetah-cub, a compliant quadruped robot. The Interational Journal of Robotics Research, 32(8), 932–950.
Sussillo, D., & Abbott, L. F. (2009). Generating coherent patterns of activity from chaotic neural networks. Neuron, 63(4), 544–557.
Urbain, G., Barasuol, V., Semini, C., Dambre, J., & wyffels, F. (2020). Stance control inspired by cerebellum stabilizes reflex-based locomotion on hyq robot. In IEEE International Conference on Robotics and Automation. ICRA 2020.
Urbain, G., Degrave, J., Carette, B., Dambre, J., & Wyffels, F. (2017). Morphological properties of mass-spring networks for optimal locomotion learning. Frontiers in Neurorobotics, 11, 16.
Urbain, G., Vandesompele, A., wyffels, F. & Dambre, J. (2018). Calibration method to improve transfer from simulation to quadruped robots. In 15th International Conference on Simulation of Adaptive Behavior, SAB 2018 (pp. 102–113).
Vanderborght, B., Ham, R. V., Lefeber, D., Sugar, T., & Hollander, K. W. (2009). Comparison of mechanical design and energy consumption of adaptable, passive-compliant actuators. The Interational Journal of Robotics Research, 28(1), 90–103.
Vu, H. Q., Yu, X., Iida, F., & Pfeifer, R. (2015). Improving energy efficiency of hopping locomotion by using a variable stiffness actuator. IEEE/ASME Transactions on Mechatronics, 21(1), 472–486.
wyffels, F., D’Haene, M., Waegeman, T., Caluwaerts, K., Nunes, C. & Schrauwen, B. (2010). Realization of a passive compliant robot dog. In 3rd IEEE-RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics, BioRob 2010 (pp. 882–886).
Zhao, Q., Nakajima, K., Sumioka, H., Hauser, H. & Pfeifer, R. (2013). Spine dynamics as a computational resource in spine-driven quadruped locomotion. In IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2013 (pp. 1445–1451).
Acknowledgements
This research was supported by the HBP Neurorobotics Platform funded from the European Union’s Horizon 2020 Framework Programme for Research and Innovation under the Specific Grant Agreement No. 785907 (Human Brain Project SGA2). Experiments were conducted on the HyQ Platform hosted and funded by the Fondazione Istituto Italiano di Tecnologia. The authors would also like to thank Shamel Fahmi for his help during the experiments and Gennaro Raiola for his support with the software.
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GU, VB, and Fw conceived the study, designed the experiments, and interpreted the results. GU and VB conducted the experiments. GU wrote the manuscript and all authors reviewed it.
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Urbain, G., Barasuol, V., Semini, C. et al. Effect of compliance on morphological control of dynamic locomotion with HyQ. Auton Robot 45, 421–434 (2021). https://doi.org/10.1007/s10514-021-09974-9
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DOI: https://doi.org/10.1007/s10514-021-09974-9