scholarly journals Stability-Guaranteed and High Terrain Adaptability Static Gait for Quadruped Robots

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4911
Author(s):  
Qian Hao ◽  
Zhaoba Wang ◽  
Junzheng Wang ◽  
Guangrong Chen
Keyword(s):  
Impedance Control ◽  
Stability Margin ◽  
Planning Method ◽  
Legged Robots ◽  
Gait Planning ◽  
Quadruped Locomotion ◽  
Quadruped Robots ◽  
Adjustment Strategy ◽  
Compliant Behavior ◽  
The Stability

Stability is a prerequisite for legged robots to execute tasks and traverse rough terrains. To guarantee the stability of quadruped locomotion and improve the terrain adaptability of quadruped robots, a stability-guaranteed and high terrain adaptability static gait for quadruped robots is addressed. Firstly, three chosen stability-guaranteed static gaits: intermittent gait 1&2 and coordinated gait are investigated. In addition, then the static gait: intermittent gait 1, which is with the biggest stability margin, is chosen to do a further research about quadruped robots walking on rough terrains. Secondly, a position/force based impedance control is employed to achieve a compliant behavior of quadruped robots on rough terrains. Thirdly, an exploratory gait planning method on uneven terrains with touch sensing and an attitude-position adjustment strategy with terrain estimation are proposed to improve the terrain adaptability of quadruped robots. Finally, the proposed methods are validated by simulations.

Stability Margin of a Metamorphic Quadruped Robot With a Twisting Trunk

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Chunsong Zhang ◽  
Chi Zhang ◽  
Jian S. Dai ◽  
Peng Qi
Keyword(s):  
Closed Loop ◽  
Stability Margin ◽  
Rigid Bodies ◽  
Quadruped Robot ◽  
Quadruped Robots ◽  
Kinematic Performance ◽  
The Stability ◽  
Twisting Angle

Abstract To date, most quadruped robots are either equipped with trunks that are rigid bodies or consist of blocks connected by passive joints. The kinematic performance of these quadruped robots is only determined by their legs. To release the mobility of trunks and enhance the performance of quadruped robots, this paper proposes a metamorphic quadruped robot with a moveable trunk (a planar six-bar closed-loop linkage), called MetaRobot I, which can implement active trunk motions. The robot can twist its trunk like natural quadrupeds. Through trunk twisting, the stability margin of the quadruped robot can be increased compared with that of a quadruped robot with a rigid trunk. The inner relationship between the stability margin and the twisting angle is analyzed in this paper. Finally, simulations are carried out to show the benefits facilitated by the twisting trunk to the quadruped robot.

Gait Planning and Simulation Analysis of a New Amphibious Quadruped Robots

2018 ◽  
Vol 30 (2) ◽  
pp. 257-264
Author(s):  
Shuo Han ◽  
◽  
Yuan Chen ◽  
Guangying Ma ◽  
Jinshan Zhang ◽  
...  
Keyword(s):  
Simulation Analysis ◽  
Stability Margin ◽  
Quadruped Robot ◽  
Working Environment ◽  
Practical Application ◽  
Quadruped Robots ◽  
Driving Mechanisms ◽  
Adams Software ◽  
New Type ◽  
The Stability

In order to allow quadruped robots to adapt to the complex working environment in the field of fisheries and aquaculture, a new type of quadruped robot with linear and rotary driving is proposed, and the kinematic inverse solution of the leg of the quadruped robot is deduced. For achieving quadruped robot smooth walking, the straight gait of the quadruped robot is planned according to the stability margin principle of motion, so that the stability margin of the machine is 20 mm when three legs supporting it. The planning gait is simulated by ADAMS software, the kinematics and dynamics analysis of the four main driving mechanisms of the robot leg were carried out, and the feasibility of using the STEP5 driving function to execute the planning gait in the quadruped robot was verified. The theoretical and simulation curve analysis results show that, the quadruped robot according to the planned gait can complete the cycle and have a stable walking. The results of this study can provide a reference for the practical application of the new amphibious quadruped robot in the fields of complex and uneven ground in the field of fisheries and aquaculture to realize exploration, fishing and transportation.

Gait planning and control of quadruped crawling robot on a slope

2019 ◽  
Vol 47 (1) ◽  
pp. 12-22
Author(s):  
Peng Wang ◽  
Chunxiao Song ◽  
Xiaoqiang Li ◽  
Peng Luo
Keyword(s):  
Position Control ◽  
Impedance Control ◽  
Switching Control ◽  
Gait Planning ◽  
Content Type ◽  
Planning And Control ◽  
Smooth Switching ◽  
The Stability ◽  
And Control ◽  
Soft Control

Purpose The gait planning and control of quadruped crawling robot affect the stability of the robot walking on a slope. The control includes the position control in the swing phase, the force control in the support phase and the switching control in the force/position switching. To improve the passing ability of quadruped crawling robot on a slope, this paper aims to propose a soft control strategy. Design/methodology/approach The strategy adopts the statically stable crawling gait as the main gait. As the robot moves forward, the position/force section switching control is adopted. When the foot does not touch the ground, the joint position control based on the variable speed PID is performed. When the foot touches the ground, the position-based impedance control is performed, and a fuzzy multi-model switching control based on friction compensation is proposed to achieve smooth switching of force and position. Findings The proposed method offers a solution for stable passage in slope environment. The quadruped crawling robot can realize smooth switching of force/position, precise positioning in the swing process and soft control of force in the supporting phase. This fact is verified by simulation and test. Originality/value The method presented in this paper takes advantage of minimal tracking errors and minimal jitters. Simulations and tests were performed to evaluate the performance.

The simplest creeping gait for a quadruped robot

2012 ◽  
Vol 227 (1) ◽  
pp. 170-177 ◽  
Author(s):  
Fei Liu ◽  
Dan Wu ◽  
Ken Chen
Keyword(s):  
Mathematical Description ◽  
Degrees Of Freedom ◽  
Stability Margin ◽  
Geometrical Model ◽  
Quadruped Robot ◽  
Center Of Gravity ◽  
Gait Planning ◽  
Directional Stability ◽  
The Stability ◽  
Initial Pattern

This article presents the simplest creeping gait (creeping gait with one center-of-gravity movement in a cycle) for a quadruped robot. The creeping gait with one center-of-gravity movement is efficient in reducing the complexity of gait planning and the control of quadrupeds. To find the simplest creeping gait, the geometrical model of a quadruped is constructed, and the omni-directional stability margin is derived to determine the stability. Based on the features of creeping gaits, the simplest possible gait is analyzed. The mathematical description is used to describe the simplest gait with the maximum omni-directional stability margin. Details of the creeping gait, including its initial pattern and its sequences, are provided. In a cycle of the creeping gait with one center-of-gravity movement, the center of gravity needs to move only once. Only 16 commands are required to move a quadruped with two degrees of freedom in each leg. An experiment conducted on the THU-WL robot proves that the gait is reliable and stable. The creeping gait with one center-of-gravity movement is a remarkable simplification for the creeping gait.

Improving the stability of gait planning for quadruped robots

2014 ◽  
Author(s):  
Sharokh Payandeh ◽  
Vahid Johari Majd ◽  
Sadegh Moradi Shoili ◽  
Majid Mohamadi Moghaddam
Keyword(s):  
Gait Planning ◽  
Quadruped Robots ◽  
The Stability

Adaptive gait planning for multi-legged robots with an adjustment of center-of-gravity

Robotica ◽  
1999 ◽  
Vol 17 (4) ◽  
pp. 391-403 ◽  
Author(s):  
Wenjie Chen ◽  
K.H. Low ◽  
S.H. Yeo
Keyword(s):  
Control Systems ◽  
Stability Margin ◽  
Longitudinal Axis ◽  
Static Stability ◽  
Center Of Gravity ◽  
Legged Robots ◽  
Rough Terrain ◽  
Lateral Direction ◽  
Gait Planning ◽  
Adaptive Gait

Adaptive gait planning is an important aspect in the development of control systems for multi-legged robots traversing on rough terrain. The problem of adaptive gait generation can be viewed as one of finding a sequence of suitable foothold on rough terrain so that legged systems maintain static stability and motion continuity. Due to the limit of static stability, deadlock situation may occur in the process of searching for a suitable foothold, if terrain contains a large number of forbidden zones. In this paper, an improved method for adaptive gait planning is presented by active compensation of stability margin, through center of gravity (CG) adjustment in the longitudinal axis and/or body translation in the lateral direction. An algorithm for the proposed method is developed and embedded in a computer program. Simulation results show that the method provides legged machines with a much larger terrain adaptivity and better deadlock-avoidance ability.

scholarly journals A Bio-Inspired Compliance Planning and Implementation Method for Hydraulically Actuated Quadruped Robots with Consideration of Ground Stiffness

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2838
Author(s):  
Xiaoxing Zhang ◽  
Haoyuan Yi ◽  
Junjun Liu ◽  
Qi Li ◽  
Xin Luo
Keyword(s):  
Harmonic Oscillation ◽  
Ground Surface ◽  
Legged Locomotion ◽  
Soft Ground ◽  
Quadruped Robots ◽  
In Series ◽  
Reaction Forces ◽  
Implementation Method ◽  
The Stability ◽  
Natural Dynamics

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.

scholarly journals Terrain classification and adaptive locomotion for a hexapod robot Qingzhui

2021 ◽  
Author(s):  
Yue Zhao ◽  
Feng Gao ◽  
Qiao Sun ◽  
Yunpeng Yin
Keyword(s):  
Legged Robots ◽  
Measurement Unit ◽  
Support Vector ◽  
Hexapod Robot ◽  
Terrain Classification ◽  
Adaptive Locomotion ◽  
Joint Torques ◽  
Active Compliance ◽  
Outdoor Environments ◽  
The Stability

AbstractLegged robots have potential advantages in mobility compared with wheeled robots in outdoor environments. The knowledge of various ground properties and adaptive locomotion based on different surface materials plays an important role in improving the stability of legged robots. A terrain classification and adaptive locomotion method for a hexapod robot named Qingzhui is proposed in this paper. First, a force-based terrain classification method is suggested. Ground contact force is calculated by collecting joint torques and inertial measurement unit information. Ground substrates are classified with the feature vector extracted from the collected data using the support vector machine algorithm. Then, an adaptive locomotion on different ground properties is proposed. The dynamic alternating tripod trotting gait is developed to control the robot, and the parameters of active compliance control change with the terrain. Finally, the method is integrated on a hexapod robot and tested by real experiments. Our method is shown effective for the hexapod robot to walk on concrete, wood, grass, and foam. The strategies and experimental results can be a valuable reference for other legged robots applied in outdoor environments.

Study on the characteristics of secondary arc current of UHV high compensation degree TCSC line under the fine-tuning mode

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Baina He ◽  
Yadi Xie ◽  
Jingru Zhang ◽  
Nirmal-Kumar C. Nair ◽  
Xingmin He ◽  
...  
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Stability Margin ◽  
Transmission Capacity ◽  
Fine Tuning ◽  
Series Compensation ◽  
Arc Current ◽  
Compensation Device ◽  
The Stability ◽  
Recovery Voltage

Abstract In the transmission line, the series compensation device is often used to improve the transmission capacity. However, when the fixed series capacitor (FSC) is used in high compensation series compensation device, the stability margin cannot meet the requirements. Therefore, thyristor controlled series compensator (TCSC) is often installed in transmission lines to improve the transmission capacity of the line and the stability of the system. For cost considerations, the hybrid compensation mode of FSC and TCSC is often adopted. However, when a single-phase grounding fault occurs in a transmission line with increased series compensation degree, the unreasonable distribution of FSC and TCSC will lead to the excessive amplitude of secondary arc current, which is not conducive to rapid arc extinguishing. To solve this problem, this paper is based on 1000 kV Changzhi-Nanyang-Jingmen UHV series compensation transmission system, using PSCAD simulation program to established UHV series compensation simulation model, The variation law of secondary arc current and recovery voltage during operation in fine tuning mode after adding TCSC to UHV transmission line is analyzed, and the effect of increasing series compensation degree on secondary arc current and recovery voltage characteristics is studied. And analyze the secondary arc current and recovery voltage when using different FSC and TCSC series compensation degree schemes, and get the most reasonable series compensation configuration scheme. The results show that TCSC compensation is more beneficial to arc extinguishing under the same series compensation. Compared with several series compensation schemes, it is found that with the increase of the proportion of TCSC, the amplitude of secondary arc current and recovery voltage vary greatly. Considering various factors, the scheme that is more conducive to accelerating arc extinguishing is chosen.

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