An Adaptive Feedforward Control Method for Under-Actuated Bipedal Walking on the Compliant Ground

Wang, Yang; Ding, Jiatao; Xiao, Xiaohui

doi:10.2316/journal.206.2017.1.206-4779

Cited by 6 publications

(5 citation statements)

References 29 publications

(39 reference statements)

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“…The nonlinear dynamic control for a novel one-legged hopping robot in flight phase is investigated. 36 Based on humanoid robots, Wang et al 37 developed an adaptive feedforward control strategy to stabilize underactuated biped robots that walk on compliant ground. However, the study of walking robots is extremely challenging for designers and producers.…”

Section: Ur Walking Mechanismmentioning

confidence: 99%

Underactuated robotics: A review

Wang

Liu

2019

International Journal of Advanced Robotic Systems

137

102

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Underactuated robotics is an emerging research direction in the field of robotics. The control input of the underactuated robot is less than the degree of freedom of the system. It has the advantages of lightweight, low energy consumption, excellent performance, and broad development prospects. This article reviews the state of the art on underactuated robotics. On the basis of previous studies, this article takes the non-holonomic constraint equation as the entry point to classify and summarize underactuated robot and their common mechanisms. The controllability of underactuated robot is further discussed. The control flow of underactuated robot is described based on the open-closed control method. In the closed-loop control, the control method based on the fuzzy system is mainly used. Finally, the difficulties in the current research of underactuated robot are summarized, and the future research directions are prospected.

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Section: Ur Walking Mechanismmentioning

confidence: 99%

Underactuated robotics: A review

Wang

Liu

2019

International Journal of Advanced Robotic Systems

137

102

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“…This section briefly introduces the dynamics of bipedal locomotion on compliant step. The compliant ground is modelled as a spring-damper equivalent system (Khadiv et al, 2019; Wang et al, 2017), which is constructed with a group of independent compliant structures (Figure 1). A compliant structure consists of a discrete elastic spring, viscous damp cell arrays, rigid ground foundation, and surface fragments.…”

Section: Modelling For Bipedal Walking On a Compliant Stepmentioning

confidence: 99%

“…By observing human gait indicates that the velocity of humans can be regulated by adjusting their posture. When the body leans forward, the walking speed increases, and when the body leans back, the walking speed automatically decreases (Wang et al, 2017). Therefore, a control strategy based on the motion state of the CoM is proposed to stabilize the complete walking process on compliant steps.…”

Section: Controller Design On Varying Height Stepsmentioning

confidence: 99%

Feedforward control for underactuated bipedal walking on compliant continuous steps with varying height

Yao

et al. 2020

Transactions of the Institute of Measurement and Control

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This study develops a feedforward control strategy based on the motion state of center-of-mass (CoM) of a robot for underactuated biped robot stable walking on compliant continuous steps with a known varying height. First, considering ground deformation, a compliant contact model is employed to characterize foot-ground interaction, and a robot–step coupling dynamic model of sagittal and lateral planes are established through decoupling modelling. Second, based on the gait characteristics of human variable-step walking, a feedforward control strategy based on the motion state of CoM is proposed. Varying height step is equivalent to varying slope, an equivalent slope angle and a desired step length can be calculated for each step according to their height. Underactuated bipedal walking control is decoupled into sagittal and lateral master-slave control. The velocity of robot CoM is considered as a system output. It is controlled through the displacement of CoM in a single walking cycle, and thus walking is stabilized. By the proposed method, the walking system is modelled as a polynomial with definite number of degrees and the controlled input is derived through a simple inverse operation on it. Its effectiveness is validated through simulations in an environment with a step varying height of less than 0.032 m. Simulation results show that the proposed method can improve the tracking performance of robot CoM velocity on varying height steps, as compared to a hybrid zero dynamic (HZD)-based controller.

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“…The compliant ground is modeled as spring-damper equivalent system (see Fig. 1) (Wang et al, 2017;Chemori et al, 2010). The compliant structure contains discrete elastic springs, viscous damp cell arrays, a rigid ground foundation, and surface fragments.…”

Section: Modelling For Bipedal Walking On a Compliant Slopementioning

confidence: 99%

Feedforward control for underactuated bipedal walking on varying compliant slopes

Yao

et al. 2018

Transactions of the Canadian Society for Mechanical Engineering

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In this paper, a feedforward control strategy is proposed to enable stable underactuated bipedal walking on varying compliant slopes with a known inclination angle, to handle the variation in natural environments. First, spring–damper units were employed in the horizontal and vertical directions to model the compliant ground, which is described as a rigid kinematic chain coupled with a spring–damper system. Second, a new definition of stable underactuated bipedal walking, based on walking speed, was proposed. Stable walking is achieved by adjusting the velocity of the biped’s center of mass (CoM) within limits that have been proven to allow at least one walking cycle. The proposed feedforward control strategy was based on the motion state of a robot’s CoM, using the new definition of stability and inspired by the gait characteristics of human walking on varying slopes. Speed control is realized by adjusting the displacement of the CoM with the change of slope to achieve stable walking. Finally, simulations were conducted to validate the proposed controller. The simulation results demonstrate that stable walking is achieved on varying compliant slopes by implementing the proposed control strategy.

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An Adaptive Feedforward Control Method for Under-Actuated Bipedal Walking on the Compliant Ground

Cited by 6 publications

References 29 publications

Underactuated robotics: A review

Underactuated robotics: A review

Feedforward control for underactuated bipedal walking on compliant continuous steps with varying height

Feedforward control for underactuated bipedal walking on varying compliant slopes

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