Abstract
There has been a rising interest in compliant legged locomotion to improve the adaptability and energy efficiency of robots. However, few approaches can be generalized to soft ground due to the lack of consideration of the ground surface. When a robot locomotes on soft ground, the elastic robot legs and compressible ground surface are connected in series. The combined compliance of the leg and surface determines the natural dynamics of the whole system and affects the stability and efficiency of the robot. This paper proposes a bio-inspired leg compliance planning and implementation method with consideration of the ground surface. The ground stiffness is estimated based on analysis of ground reaction forces in the frequency domain, and the leg compliance is actively regulated during locomotion, adapting them to achieve harmonic oscillation. The leg compliance is planned on the condition of resonant movement which agrees with natural dynamics and facilitates rhythmicity and efficiency. The proposed method has been implemented on a hydraulic quadruped robot. The simulations and experimental results verified the effectiveness of our method.
Highlights
Biswanath Samanta and HamedLegged robots have superior mobility and maneuverability in complex unstructured environments, benefitting from the ability afforded by their morphology and varied gaits [1]
Versatile high-performance robots, such as BigDog, Spot, and Atlas developed by Boston Dynamics [2], the MIT cheetah series [3,4,5,6,7], the HyQ [8,9] and the ANYmal [10,11] developed by IIT and ETH Zurich, the Aliengo [12] from the Unitree
The stiffness of virtual leg k in spring-loaded inverted pendulum (SLIP) model roughly equals that of the quadruped robot, and the point mass m at the center of mass (CoM) is about half the body mass of the robot moving at a symmetrical gait
Summary
Legged robots have superior mobility and maneuverability in complex unstructured environments, benefitting from the ability afforded by their morphology and varied gaits [1]. Through the impulse scaling of foot reaction forces obtained from biological research, the Cheetah robots achieved high performance in terms of locomotion efficiency and agility without much concern regarding contact dynamics. Demonstrate better active control methods is still subject to the responsiveness of the actuator to a great extent adaptability These methods improve the robot’s performance in challenging terrains due in to practical the wider applications. The compliance of the robot leg is actively controlled to offer virtual elasticity mated during locomotion based on the analysis of ground reaction forces in the frequency regulated as changes of locomotion parameters and the environment to achieve harmonic domain. Is regulated as changes of locomotion parameters and the environment to achieve In developing the bio-inspired compliance planning and implementation method, harmonic oscillation of the elastic leg-ground system in the stance phase.
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