Volume 14, Issue 2, April 2017, Pages 218–231

• Qingyu Liu, 
• Xuedong Chen, 
• Bin Han, 
• Zhiwei Luo, 
• Xin Luo^, 

• State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, China

• Abstract

  This paper presents a control approach for bounding gait of quadruped robots by applying the concept of Virtual Constraints (VCs). A VC is a relative motion relation between two related joints imposed to the robots in terms of a specified gait, which can drive the robot to run with desired gait. To determine VCs for highly dynamic bounding gait, the limit cycle motions of the passive dynamic model of bounding gait are analyzed. The leg length and hip/shoulder angle trajectories corresponding to the limit cycles are parameterized by leg angles using 4 th-order polynomials. In order to track the calculated periodic motions, the polynomials are imposed on the robot as virtual motion constraints by a high-level state machine controller. A bounding speed feedback strategy is introduced to stabilize the robot running speed and enhance the stability. The control approach was applied to a newly designed lightweight bioinspired quadruped robot, AgiDog. The experimental results demonstrate that the robot can bound at a frequency up to 5 Hz and bound at a maximum speed of 1.2 m·s⁻¹ in sagittal plane with a Froude number approximating to 1.

  Keywords

  • bioinspired quadruped; 
  • bounding gait; 
  • virtual constraints; 
  • passive dynamics
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  • Full text is available at http://www.sciencedirect.com/science/article/pii/S1672652917300045