Abstract
Most state-of-the-art bipedal robots are designed to be anthropomorphic, and therefore possess articulated legs with knees. Whilst this facilitates smoother, human-like locomotion, there are implementation issues that make walking with straight legs difficult. Many robots have to move with a constant bend in the legs to avoid a singularity occurring at the knee joints. The actuators must constantly work to maintain this stance, which can result in the negation of energy-saving techniques employed. Furthermore, vertical compliance disappears when the leg is straight and the robot undergoes high-energy loss events such as impacts from running and jumping, as the impact force travels through the fully extended joints to the hips. In this paper, we attempt to improve energy efficiency in a simple yet effective way: attaching bungee cords as elastic elements in parallel to the legs of a novel, knee-less biped robot SLIDER, and show that the robot’s prismatic hip joints preserve vertical compliance despite the legs being constantly straight. Due to the nonlinear dynamics of the bungee cords and various sources of friction, Bayesian Optimization is utilized to find the optimals configuration of bungee cords that achieves the largest reduction in energy consumption. The optimal solution found saves 15% of the energy consumption compared to the robot configuration without parallel elastic elements. Additional Video: https://youtu.be/ZTaG9_-Dz8A
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Notes
- 1.
Due to the COVID-19 pandemic, access to the physical robot has been limited. We thus focus on validating the concept and do not focus on whole-body walking experiments.
References
Alexander, R.: Three uses for springs in legged locomotion. Int. J. Robot. Res. 9(2), 53–61 (1990)
Radkhah, K., Von Stryk, O.: A study of the passive rebound behavior of bipedal robots with stiff and different types of elastic actuation. In: 2014 IEEE International Conference on Robotics and Automation (ICRA), pp. 5095–5102. IEEE (2014)
Sreenath, K., Park, H.-W., Poulakakis, I., Grizzle, J.W.: A compliant hybrid zero dynamics controller for stable, efficient and fast bipedal walking on MABEL. Int. J. Rob. Res. 30(9), 1170–1193 (2011)
Pratt, G.A., Williamson, M.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 (1995)
Pratt, J., et al.: Capturability-based analysis and control of legged locomotion, part 2: Application to M2V2, a lower-body humanoid. Int. J. Rob. Res. 31(10), 1117–1133 (2012)
Hobbelen, D., de Boer, T., Wisse, M.: System overview of bipedal robots flame and tulip: tailor-made for limit cycle walking. In: 2008 IEEE/RSJ International Conference on Intelligent Robots and Systems, pp. 2486–2491. IEEE (2008)
Kormushev, P., Ugurlu, B., Caldwell, D.G., Tsagarakis, N.G.: Learning to exploit passive compliance for energy-efficient gait generation on a compliant humanoid. Auton. Robot. 43(1), 79–95 (2018). https://doi.org/10.1007/s10514-018-9697-6
Yang, T., Westervelt, E.R., Schmiedeler, J.P., Bockbrader, R.A.: Design and control of a planar bipedal robot ERNIE with parallel knee compliance. Auton. Robot. 25(4), 317 (2008)
Mazumdar, A., et al.: Parallel elastic elements improve energy efficiency on the STEPPR bipedal walking robot. IEEE/ASME Trans. Mechatron. 22(2), 898–908 (2017)
Folkertsma, G.A., Kim, S., Stramigioli, S.: Parallel stiffness in a bounding quadruped with flexible spine. In: 2012 IEEE/RSJ International Conference on Intelligent Robots and Systems, pp. 2210–2215. IEEE (2012)
Lynch, K.M., Park, F.C.: Modern Robotics: Mechanics, Planning, and Control. Cambridge University Press, Cambridge (2017)
Kajita, S., et al.: Biped walking pattern generation by using preview control of zero-moment point. In: 2003 IEEE International Conference on Robotics and Automation (Cat. No. 03CH37422), vol. 2, pp. 1620–1626. IEEE (2003)
Dallali, H., Kormushev, P., Tsagarakis, N., Caldwell, D.G.: Can active impedance protect robots from landing impact? In: Proceedings IEEE International Conference on Humanoid Robots (Humanoids 2014), Madrid, Spain (2014)
Wang, K., Shah, A., Kormushev, P.: SLIDER: a bipedal robot with knee-less legs and vertical hip sliding motion. In: Proceedings 21st International Conference on Climbing and Walking Robots and Support Technologies for Mobile Machines (CLAWAR 2018), Panama (2018)
Wang, K., et al.: Design and control of SLIDER: an ultra-lightweight, knee-less, low-cost bipedal walking robot. In: Proceedings IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2020), Las Vegas, USA, October 2020
Schauß, T., Scheint, M., Sobotka, M., Seiberl, W., Buss, M.: Effects of compliant ankles on bipedal locomotion. In: 2009 IEEE International Conference on Robotics and Automation, pp. 2761–2766. IEEE (2009)
Farrell, K., Chevallereau, C., Westervelt, E.: Energetic effects of adding springs at the passive ankles of a walking biped robot. In: Proceedings 2007 IEEE International Conference on Robotics and Automation, pp. 3591–3596. IEEE (2007)
Kormushev, P., Ugurlu, B., Calinon, S., Tsagarakis, N.G., Caldwell, D.G.: Bipedal walking energy minimization by reinforcement learning with evolving policy parameterization. In: 2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, pp. 318–324. IEEE (2011)
Arakawa, T., Fukuda, T.: Natural motion trajectory generation of biped locomotion robot using genetic algorithm through energy optimization. In: 1996 IEEE International Conference on Systems, Man and Cybernetics. Information Intelligence and Systems (Cat. No. 96CH35929), vol. 2, pp. 1495–1500. IEEE (1996)
Calandra, R., Gopalan, N., Seyfarth, A., Peters, J., Deisenroth, M.P.: Bayesian gait optimization for bipedal locomotion. In: International Conference on Learning and Intelligent Optimization, pp. 274–290. Springer (2014)
Kockelman, J., Hubbard, M.: Bungee jumping cord design using a simple model. Sports Eng. 7(2), 89–96 (2004)
Odrive: Odrive robotics. https://odriverobotics.com/
Rasmussen, C.E.: Gaussian processes in machine learning. In: Summer School on Machine Learning, pp. 63–71. Springer (2003)
Calandra, R., Seyfarth, A., Peters, J., Deisenroth, M.P.: An experimental comparison of Bayesian optimization for bipedal locomotion. In: 2014 IEEE International Conference on Robotics and Automation (ICRA), pp. 1951–1958. IEEE (2014)
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Wang, K., Saputra, R.P., Foster, J.P., Kormushev, P. (2022). Improved Energy Efficiency via Parallel Elastic Elements for the Straight-Legged Vertically-Compliant Robot SLIDER. In: Chugo, D., Tokhi, M.O., Silva, M.F., Nakamura, T., Goher, K. (eds) Robotics for Sustainable Future. CLAWAR 2021. Lecture Notes in Networks and Systems, vol 324. Springer, Cham. https://doi.org/10.1007/978-3-030-86294-7_12
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