Intelligent Walking of Humans and Robots

• Applicants: Privatdozent Dr. Roy Müller; Professor Dr. Daniel J. Rixen
• Subject Area: Automation, Mechatronics, Control Systems, Intelligent Technical Systems, Robotics
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 327485414

• Final Report Year: 2023

Final Report Abstract

In the first phase of the project, the gait of human was compared to the one of a humanoid robot (Lola). The gait of humans shows specific patterns: the forces exerted on the ground during a gait cycle are always direct towards a virtual pivot point located above the center of mass (CoM) of humans, guaranteeing thereby that the torso is maintained upright (stability). This observation is known as Virtual Pivot Point (VPP). The humanoid Lola does not show a VPP during walking, indicating that, although its gait looks human-like, the walking-pattern generated by the planning and control strategy of a humanoid is very different from the strategy developed by humans (which leads to a VPP). This follow-up project was organized in two parts, A and B. In subproject A, analysis of previous experiments indicated that a VPP exists also during the double support phase of humans and is located above the CoM during walking, under the CoM for running. It was also found that the vertical VPP position did not differ between patients with Down syndrome and healthy participants. New measurements showed that the existence of a VPP is still observed when humans imitate Lola’s gait or walk with a maipulated center of pressure, suggesting that gaiting without VPP would require a significant perturbation of the musculoskeletal system. This is also suggested by simulation results, where large deviations in the VPP could be obtained during stable gaiting, and where it was shown that experimentally observed anticipatory muscle adaptations increase robustness to background changes. In subproject B, motion patterns of the robot Lola were changed by varying control parameters to investigate if Lola could possibly exhibit a VPP. Even then, the ground reaction forces show no intersection point in the sense of a VPP and it was not possible to set such a VPP in Lola with the current operating strategies. Analyzing the forces and moments acting in Lola, and the dynamics of its different parts, we discovered that the absence of a VPP in Lola can ultimately be explained by the large interaction forces and moments generated between Lola’s hips and legs during walking. Such interactions are a direct consequence of the planning strategy used in Lola. These observations led to new ideas that will be exploited in the future to rethink the design and control of humanoids.

Publications

• Quintic Spline Collocation for Real-Time Biped Walking-Pattern Generation with variable Torso Height. 2019 IEEE-RAS 19th International Conference on Humanoid Robots (Humanoids), 56-63. IEEE.
  Seiwald, Philipp; Sygulla, Felix; Staufenberg, Nora-Sophie & Rixen, Daniel
  
• Negotiating ground level perturbations in walking: Visual perception and expectation of curb height modulate muscle activity. Journal of Biomechanics, 113, 110121.
  Müller, Roy; Vielemeyer, Johanna & Häufle, Daniel F.B.
  
• Postural stability in human running with step-down perturbations: an experimental and numerical study. Royal Society Open Science, 7(11), 200570.
  Drama, Özge; Vielemeyer, Johanna; Badri-Spröwitz, Alexander & Müller, Roy
  
• Ground reaction forces intersect above the center of mass in single support, but not in double support of human walking. Journal of Biomechanics, 120, 110387.
  Vielemeyer, Johanna; Müller, Roy; Staufenberg, Nora-Sophie; Renjewski, Daniel & Abel, Rainer
  
• LOLA v1.1 – An Upgrade in Hardware and Software Design for Dynamic Multi-Contact Locomotion. 2020 IEEE-RAS 20th International Conference on Humanoid Robots (Humanoids), 9-16. IEEE.
  Seiwald, Philipp; Wu, Shun-Cheng; Sygulla, Felix; Berninger, Tobias F. C.; Staufenberg, Nora-Sophie; Sattler, Moritz F.; Neuburger, Nicolas; Rixen, Daniel & Tombari, Federico
  
• Evaluating anticipatory control strategies for their capability to cope with step-down perturbations in computer simulations of human walking. Scientific Reports, 12(1).
  Schreff, Lucas; Haeufle, Daniel F. B.; Vielemeyer, Johanna & Müller, Roy
  
• A Study on the Intersection of Ground Reaction Forces during Overground Walking in Down Syndrome: Effects of the Pathology and Left–Right Asymmetry. Symmetry, 15(2), 544.
  Vielemeyer, Johanna; Sole, Cristina; Galli, Manuela; Zago, Matteo; Müller, Roy & Condoluci, Claudia
  
• Walking like a robot: do the ground reaction forces still intersect near one point when humans imitate a humanoid robot?. Royal Society Open Science, 10(5).
  Vielemeyer, Johanna; Staufenberg, Nora-Sophie; Schreff, Lucas; Rixen, Daniel & Müller, Roy
  
• ‘Virtual pivot point’ in human walking: Always experimentally observed but simulations suggest it may not be necessary for stability. Journal of Biomechanics, 153, 111605.
  Schreff, Lucas; Haeufle, Daniel F.B.; Badri-Spröwitz, Alexander; Vielemeyer, Johanna & Müller, Roy