Mechanisms of Semicircular Feet in Dynamic Bipedal Walking
Fumihiko Asano, Dr. Eng.
Keywords: Passive dynamic walking, Biped robots, Legged locomotion, Semicircular feet, Limit cycle, Underactuated system, Mechanical energy, Efficiency, Sole, Foot, Feet, Zero dynamics


Abstract

Achieving energy-efficient and high-speed dynamic walking has become one of the main subjects of research in the area of robotic biped locomotion, and passive dynamic walking has a great deal of attention as a solution to this problem. It is empirically known that the convex curve of the foot, which characterizes the passive dynamic walker, has an important effect on increasing the walking speed.
This research project theoretically investigates what effect semicircular feet had on dynamic bipedal walking. By clarifying driving mechanisms of fully-actuated compass-like biped robots with flat feet, importance of ankle-joint torque was mathematically understood. A planar underactuated compass-like biped model with semicircular feet is introduced and it is shown that virtual passive dynamic walking by hip-joint torque only can be realized based on the rolling effect which is equivalent to the ankle-joint torque. Magnitude of the virtual ankle-joint torque is uniquely determined by the foot radius, robot's total mass and stance-leg angle with respect to vertical.
On the other hand, it is theoretically clarified that increasing walking speed compared with flat feet models is achieved not by the rolling effect during the single support phase but by the effect of reducing energy dissipation at heel strikes. It is also shown that there is a condition to reduce energy dissipation to zero through analyses based on singular value decomposition.
We provide novel insights on biped gait generation and control in ZMP-free robots throughout this research.



Methods

Please click the following figures for the detail.





Selected papers
  1. Fumihiko Asano and Zhi-Wei Luo, "On Energy-Efficient and High-Speed Dynamic Biped Locomotion with Semicircular Feet," Proc. of the 2006 IEEE/RSJ Int. Conf. on Intelligent Robots and Systems (IROS), pp. 5901--5906, Oct. 2006. [Download]
  2. Fumihiko Asano and Zhi-Wei Luo, "Dynamic Analyses of Underactuated Virtual Passive Dynamic Walking," Proc. of the 2007 IEEE Int. Conf. on Robotics and Automation (ICRA), pp. 3210--3217, April 2007.
  3. Fumihiko Asano and Zhi-Wei Luo, "The Effect of Semicircular Feet on Energy Dissipation by Heel-strike in Dynamic Bipedal Walking," Proc. of the 2007 IEEE Int. Conf. on Robotics and Automation (ICRA), pp. 3976--3981, April 2007.

Movie collections

Please watch the following movies!

Videos in CCS2006/IROS2006 presentation
  1. Underactuated virtual passive dynamic walking with semicircular feet
  2. Underactuated virtual passive dynamic walking with semicircular feet (Slow motion)
Videos in RSJ2006/IROS2006 presentation
  1. Underactuated virtual passive dynamic walking with semicircular feet and knees
  2. Underactuated virtual passive dynamic walking with semicircular feet and knees (Slow motion)
  3. Underactuated virtual passive dynamic walking with semicircular feet and knees (with viscosity at knee-joint)
  4. Underactuated virtual passive dynamic walking with semicircular feet and knees (with viscosity at knee-joint, Slow motion)


Programs for MaTX

  1. Underactuated virtual passive dynamic walking with semicircular feet


Acknowledgment
This research project was sponsored by Bio-Mimetic Control Research Center , The Institute of Physical and Chemical Research (RIKEN) . It is a pleasure to acknowledge the hospitality and encouragement of the members of environment adaptive robotic systems laboratory. It is also deeply indebted to Mr. Yuji Harata, Uno & Taji Lab. , Nagoya University, for their considerable assistance and numerical analyses with the investigation of redundant models.
This work was partially supported by a Grants-in-Aid for Scientific Research, (B) No. 18360115, provided by the Japan Society for the Promotion of Science (JSPS).


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