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Active Balance Control of Humanoid Locomotion Based on Foot Position Compensation

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Journal of Bionic Engineering 2020年第1期17卷 134-147页

作者： chengju liu Tong Zhang Ming liu Qijun Chen School of Electronics and Information Engineering Tongji UniversityShanghai 201804China School of Electronic and Computer Engineering Hong Kong University of Science and TechnologyHong Kong 999077China

A foot positioning compensator is developed in this paper for a full-body humanoid to retrieve its balance during continuous walking.An online Foot Position Compensator(FPC)is designed to improve the robustness of biped walking,which can modify predefined step position and step duration online with sensory feedback.Foot placement parameters are learned by the FPC based on the Policy Gradient Reinforcement Learning(PGRL)method.Moreover,the FPC assists the humanoid robot in rejecting external disturbances and recovering the walking position by re-planning the trajectories of walking pattern and the Center of Mass(CoM).An upper body pose control strategy is also presented to further enhance the performance of humanoid robots to overcome strong external disturbances.The advantages of this proposed method are that it neither requires prior information about the walking terrain conditions,nor relies on range sensor information for surface topology measurement.The effectiveness of the proposed method is verified via Webots simulation and real experiments on a full-body humanoid NAO robot.

关键词： humanoid walking active balance Foot Positioning Compensation(FPC) Policy Gradient Reinforcement Learning(PGRL)

Adaptive walking control of quadruped robots based on central pattern generator (CPG) and reflex

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控制理论与应用（英文版） 2013年第3期11卷 386-392页

作者： chengju liu Qijun CHEN Guoxing WANG Department of Electronics and Information Engineering and Key Laboratory of Embedded System and Service Computing Ministry of Education Tongji University

This paper presents a central pattern generator （CPG） and vestibular reflex combined control strategy for a quadruped robot. An oscillator network and a knee-to-hip mapping function are presented to realize the rhythmic motion for the quadruped robot. A two-phase parameter tuning method is designed to adjust the parameters of oscillator network. First, based on the numerical simulation, the influences of the parameters on the output signals are analyzed, then the genetic algorithm （GA） is used to evolve the phase relationships of the oscillators to realize the basic animal-like walking pattern. Moreover, the animal＇s vestibular reflex mechanism is mimicked to realize the adaptive walking of the quadruped robot on a slope terrain. Coupled with the sensory feedback information, the robot can walk up and down the slope smoothly. The presented bio-inspired control method is validated through simulations and experiments with AIBO. Under the control of the presented CPG and vestibular reflex combined control method, AIBO can cope with slipping, falling down and walk on a slope successfully, which demonstrates the effectiveness of the proposed walking control method.

关键词： CPG Walking control Quadruped robot Vestibular reflex

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Multi-Layered CPG for Adaptive Walking of Quadruped Robots

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Journal of Bionic Engineering 2018年第2期15卷 341-355页

作者： chengju liu Li Xia Changzhu Zhang Qijun Chen School of Electronics and Information Engineering Tongji University Shanghai 201804 China

This work concerns biped adaptive walking control on slope terrains with online trajectory generation. In terms of the lack of satis- factory performances of the traditional simplified single-layered Central Pattern Generator （CPG） model in engineering applications where robots face unknown environments and access feedback, this paper presents a Multi-Layered CPG （ML-CPG） model based on a half-center CPG model. The proposed ML-CPG model is used as the underlying low-level controller for a quadruped robot to generate adaptive walking patterns. Rhythm-generation and pattern formation interneurons are modeled to promptly generate motion rhythm and patterns for motion sequence control, while motoneurons are modeled to control the output strength of the joint in real time according to feedback. Referring to the motion control mechanisms of animals, a control structure is built for a quadruped robot. Multi-sensor models abstracted from the neural reflexes of animals are involved in all the layers of neurons through various feedback paths to achieve adaptability as well as the coordinated motion control of a robot＇s limbs. The simulation experiments verify the effectiveness of the pre- sented ML-CPG and multi-layered reflexes strategy.

关键词： Multi-Layered CPG （ML-CPG） biological reflex quadruped robot adaptive walking

Adaptive Walking Control of Biped Robots Using Online Trajectory Genera- tion Method Based on Neural Oscillators

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Journal of Bionic Engineering 2016年第4期13卷 572-584页

作者： chengju liu Danwei Wang Erik David Goodman Qijun Chen School of Electronics and Information Engineering Tongji University Shanghai 201804 China School of Electrical and Electronic Engineering Nanyang Technological University Manyang Avenue 639798 Singapore BEACON Center for the Study of Evolution in Action Michigan State University East Lansing 48824 USA

This work concerns biped adaptive walking control on irregular terrains with online trajectory generation. A new trajectory generation method is proposed based on two neural networks. One oscillatory network is designed to generate foot trajectory, and another set of neural oscillators can generate the trajectory of Center of Mass （CoM） online. Using a motion engine, the characteristics of the workspace are mapped to the joint space. The entraining property of the neural oscillators is exploited for adaptive walking in the absence of a priori knowledge of walking conditions. Sensory feedback is applied to modify the gen- erated trajectories online to improve the walking quality. Furthermore, a staged evolutionary algorithm is developed to tune system parameters to improve walking performance. The developed control strategy is tested using a humanoid robot on ir- regular terrains. The experiments verify the success of the presented strategy. The biped robot can walk on irregular terrains with varying slopes, unknown bumps and stairs through autonomous adjustment of its walking patterns.

关键词： biped robot adaptive walking neural oscillator trajectory generation staged evolution algorithm

Dynamic Walking of AIBO with Hopf Oscillators

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 612-617页

作者： ZHANG Jiaqi TOMIZUKA Masayoshi CHEN Qijun liu chengju College of Electronic Information and Engineering Tongji University Shanghai 201804 China College of Electronic Information andEngineering Tongji University Shanghai 201804 China The Key Laboratory of Embedded System and Service Computing Ministry of Education Tongji University Shanghai 201804 China

More and more biological evidences have been found that neural networks in the spinal cord, referred to as ＂central pattern generators＂（CPGs）, govern locomotion. CPGs are capable of producing rhythmic movements, such as swimming, flying, and walking, even when isolated from the brain and sensory inputs. If we could build up any models that have similar functions as CPGs, it will be much easier to design better locomotion for robots. In this paper, a self-training environment is designed and through genetic algorithm （GA）, walking trajectories for every foot of AIBO are generated at first. With this acquired walking pattern, AIBO gets its fastest locomotion speed. Then, this walking pattern is taken as a reference to build CPGs with Hopf oscillators. By changing corresponding parameters, the frequencies and the amplitudes of CPGs＇ outputs can be adjusted online. The limit cycle behavior of Hopf oscillators ensures the online adjustment and the walking stability against perturbation as well. This property suggests a strong adaptive capacity to real environments for robots. At last, simulations are carried on in Webots and verify the proposed method.

关键词： central pattern generators（CPGs） Hopf Oscillators walking control AIBO Webots

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Methods Synthesis of Central Pattern Generator Inspired Biped Walking Control

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Methods Synthesis of Central Pattern Generator Inspired Bipe...

Survey of locomotion control of legged robots inspired by biological concept

2015年中国智能自动化学术会议

作者： chengju liu Qijun Chen School of Electronics and Information Engineering Tongji University

Bio-inspired locomotion control method is one of the ways to promote the site application of biped robots. This paper synthesizes the main idea and structure of central pattern generator(CPG) inspired biped walking control methods into two kinds of common strategies: joint space control methods and workspace control methods. The key problems of these two approaches are deeply explored.Finally, the research direction of the CPG-inspired control method is discussed. The motivation of this paper is to synthesize the current mainly methods for biped robots to present a practical guide to researchers and engineers interested in the CPG-inspired control approaches.

关键词： Biped robot Walking control Central pattern generator（CPG） Joint space control Workspace control

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Science in China(Series F) 2009年第10期52卷 1715-1729页

作者： WUQiDi liu chengju ZHANG JiaQi CHEN QiJun School of Electronics and Information Engineering Tongji University Shanghai 201804 China The Key Laboratory of Embedded System and Service Computing Ministry of Education Tongji University Shanghai 201804 China

Compared with wheeled mobile robots, legged robots can easily step over obstacles and walk through rugged ground. They have more flexible bodies and therefore, can deal with complex environment. Nevertheless, some other issues make the locomotion control of legged robots a much complicated task, such as the redundant degree of freedoms and balance keeping. From literatures, locomotion control has been solved mainly based on programming mechanism. To use this method, walking trajectories for each leg and the gaits have to be designed, and the adaptability to an unknown environment cannot be guaranteed. From another aspect, studying and simulating animals＇ walking mechanism for engineering application is an efficient way to break the bottleneck of locomotion control for legged robots. This has attracted more and more attentions. Inspired by central pattern generator （CPG）, a control method has been proved to be a successful attempt within this scope. In this paper, we will review the biological mechanism, the existence evidences, and the network properties of CPG. From the en- gineering perspective, we will introduce the engineering simulation of CPG, the property analysis, and the research progress of CPG inspired control method in locomotion control of legged robots. Then, in our research, we will further discuss on existing problems, hot issues, and future research directions in this field.

关键词： biological inspired control central pattern generator (CPG) locomotion control

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Disturbance Rejection Based on Momentum Compensation for Humannoid Robots

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Disturbance Rejection Based on Momentum Compensation for Hum...

Research on resonant ring-modified photonic crystal line defect slow-light waveguide

第36届中国控制会议

作者： chengju liu Jing NING Jing YANG Qijun CHEN School of Electronics and Information Engineering Tongji University

ISBN: (纸本)9781538629185

Robust motion is of great significance when humanoids are placed in complex and uncertain environments.In this paper,multitasks are merged in the way of null space projection according to their priorities.Momentum compensation is considered as one task and utilized to reject unknown disturbances.Two strategies are put forward to restrain the sudden change of momentum.One is to calculate the correction in the joint space with Resolved Momentum Control（RMC） method,the other is to add an end-effector tracking motion in the task space.Experiments are designed to test the proposed algorithm with Nao robot in simulation and the results show that the robot is able to rectify itself to the pre-planned steady stance while encountering undefined external forces.

关键词： Humanoid robot momentum compensation disturbance rejection Multi-tasking system

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Optoelectronics Letters 2024年

作者： liu Qianzhen Ma chengju Li Yan School of Science Xi'an Shiyou University

This paper presents a photonic crystal （PhC） line-defect slow-light waveguide modified by resonant rings. We introduce resonant rings into the line defect， constructing a slow-light waveguide with high normalized delay bandwidth product （NDBP） and low group velocity dispersion （GVD）. We simulate， analyze， and optimize the structural parameters of this slow-light waveguide using the finite difference time domain （FDTD） method， theoretically achieving a maximum group index of 3.7， maximum bandwidth of 15.6 nm， and maximum NDBP of 0.4416 for slow-light effect. The resonant ring-modified PhC slow-light waveguide designed in this paper exhibits GVD lower than the order of 10-20s2/m over a normalized frequency range from 0.3554 to 0.4175. This study is expected to provide theoretical references for the study of slow-light buffering devices based on PhCs with high NDBP values.

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