scholarly journals Hierarchically Planning Static Gait for Quadruped Robot Walking on Rough Terrain

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Xingdong Li ◽  
Hewei Gao ◽  
Jian Li ◽  
Yangwei Wang ◽  
Yanling Guo
Keyword(s):  
Hierarchical Structure ◽  
Classical Model ◽  
Quadruped Robot ◽  
Rough Terrain ◽  
Simulation Environment ◽  
Terrain Features ◽  
2D Space ◽  
Robot Body

Quadruped robot has great potential to walk on rough terrain, in which static gait is preferred. A hierarchical structure based controlling algorithm is proposed in this paper, in which trajectory of robot center is searched, and then static gaits are generated along such trajectory. Firstly, cost map is constructed by computing terrain features under robot body and cost of selecting footholds at default positions, and then the trajectory of robot center in 2D space is searched using heuristic A⁎ algorithm. Secondly, robot state is defined from foothold and robot pose, and then state series are searched recursively along the trajectory of robot center to generate static gaits, where a tree-like structure is used to store such states. Lastly, a classical model for quadruped robot is designed, and then the controlling algorithm proposed in the paper is demonstrated on such robot model for both structured terrain and complex unstructured terrain in a simulation environment.

scholarly journals Learning the Cost Function for Foothold Selection in a Quadruped Robot

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1292 ◽  
Author(s):  
Xingdong Li ◽  
Hewei Gao ◽  
Fusheng Zha ◽  
Jian Li ◽  
Yangwei Wang ◽  
...  
Keyword(s):  
Cost Function ◽  
Weight Vector ◽  
Quadruped Robot ◽  
Training Data ◽  
Rough Terrain ◽  
Weighted Sum ◽  
Data Set ◽  
Tof Camera ◽  
The Cost ◽  
Terrain Features

This paper is focused on designing a cost function of selecting a foothold for a physical quadruped robot walking on rough terrain. The quadruped robot is modeled with Denavit–Hartenberg (DH) parameters, and then a default foothold is defined based on the model. Time of Flight (TOF) camera is used to perceive terrain information and construct a 2.5D elevation map, on which the terrain features are detected. The cost function is defined as the weighted sum of several elements including terrain features and some features on the relative pose between the default foothold and other candidates. It is nearly impossible to hand-code the weight vector of the function, so the weights are learned using Supporting Vector Machine (SVM) techniques, and the training data set is generated from the 2.5D elevation map of a real terrain under the guidance of experts. Four candidate footholds around the default foothold are randomly sampled, and the expert gives the order of such four candidates by rotating and scaling the view for seeing clearly. Lastly, the learned cost function is used to select a suitable foothold and drive the quadruped robot to walk autonomously across the rough terrain with wooden steps. Comparing to the approach with the original standard static gait, the proposed cost function shows better performance.

Optimization of a Planar Quadruped Dynamic Leap

2008 ◽  
Author(s):  
Subhrajit Bhattacharya ◽  
Sachin Chitta ◽  
Vijay Kumar ◽  
Daniel Lee
Keyword(s):  
Quadruped Robot ◽  
Experimental Results ◽  
Walking Robots ◽  
Rough Terrain

Quadruped walking robots need to handle high obstacles like steps that are often not kinematically reachable. We present a dynamic leap that allows a quadruped robot to put its front legs up onto a high rock or ledge, a motion we have found is critical to being able to locomote over rough terrain. The leaping motion was optimized using a simulated planar quadruped model. We present experimental results for the implementation of this optimized motion on a real quadruped robot.

Research on Gait Analysis and Planning of Quadruped Search-Rescue Robot

2011 ◽  
Vol 121-126 ◽  
pp. 1484-1488 ◽  
Author(s):  
Peng Wang ◽  
Xin Li ◽  
Wen Hao Jiang ◽  
Shao Chen Kang ◽  
Jing Lei Xin
Keyword(s):  
Simulation Model ◽  
Degrees Of Freedom ◽  
Quadruped Robot ◽  
Search And Rescue ◽  
Actual Structure ◽  
Walking Machine ◽  
Rescue Robot ◽  
Simulation Results ◽  
Motion Characteristics ◽  
Robot Body

The search and rescue robot has the characteristics of quadruped walking machine. According to the actual structure of the quadruped robot body，the walking pose of the robot are planned，based on the study of the animal gait．The distributions of degrees-of-freedom is analyzed to ensure stable walking. A simulation model of quadruped search and rescue robot is established in ADAMS, and the motion characteristics of the system are observed using the simulation model established. Simulation results show that the motion characteristics of the system are closed related to the length of stride.

Normalized Energy Stability Margin Based Analysis of Omni-Directional Static Walking of a Quadruped Robot on Rough Terrain

2011 ◽  
Vol 383-390 ◽  
pp. 7401-7405
Author(s):  
Lei Zhang ◽  
Shan Gao
Keyword(s):  
Stability Criterion ◽  
Simulation Experiment ◽  
Stability Margin ◽  
Quadruped Robot ◽  
Center Of Gravity ◽  
Energy Stability ◽  
Rough Terrain ◽  
The Stability

With Normalized Energy Stability Margin(Sne ) as stability criterion, this paper studies the tumbles of omni-directional static walking of a quadruped robot around the line connecting two adjacent supporting legs on rough terrain, proposes the method to improve the stability of quadruped robot by increasing the (Sne ) value, which is realized by lowering the height of center of gravity(COG), and finally substantiates the feasibility of the method through a simulation experiment.

scholarly journals Dynamic Turning of a Soft Quadruped Robot by Changing Phase Difference

2021 ◽  
Vol 8 ◽  
Author(s):  
Hiroaki Tanaka ◽  
Tsung-Yuan Chen ◽  
Koh Hosoda
Keyword(s):  
Phase Difference ◽  
Quadruped Robot ◽  
Artificial Muscles ◽  
Soft Robot ◽  
Contact Pattern ◽  
Soft Body ◽  
Pneumatic Artificial Muscles ◽  
Left And Right ◽  
Body Dynamic ◽  
Robot Body

Dynamic locomotion of a quadruped robot emerges from interaction between the robot body and the terrain. When the robot has a soft body, dynamic locomotion can be realized using a simple controller. This study investigates dynamic turning of a soft quadruped robot by changing the phase difference among the legs of the robot. We develop a soft quadruped robot driven by McKibben pneumatic artificial muscles. The phase difference between the hind and fore legs is fixed whereas that between the left and right legs is changed to enable the robot to turn dynamically. Since the robot legs are soft, the contact pattern between the legs and the terrain can be varied adaptively by simply changing the phase difference. Experimental results demonstrate that changes in the phase difference lead to changes in the contact time of the hind legs, and as a result, the soft robot can turn dynamically.

scholarly journals Self-Stabilising Quadrupedal Running by Mechanical Design

2009 ◽  
Vol 6 (1) ◽  
pp. 73-85 ◽  
Author(s):  
Panagiotis Chatzakos ◽  
Evangelos Papadopoulos
Keyword(s):  
Mechanical System ◽  
Mechanical Design ◽  
Quadruped Robot ◽  
The Self ◽  
Rough Terrain ◽  
Stable Regime ◽  
Quadruped Robots ◽  
The Stability ◽  
Running Robots ◽  
Body Inertia

Dynamic stability allows running animals to maintain preferred speed during locomotion over rough terrain. It appears that rapid disturbance rejection is an emergent property of the mechanical system. In running robots, simple motor control seems to be effective in the negotiation of rough terrain when used in concert with a mechanical system that stabilises passively. Spring-like legs are a means for providing self-stabilising characteristics against external perturbations. In this paper, we show that a quadruped robot could be able to perform self-stable running behaviour in significantly broader ranges of forward speed and pitch rate with a suitable mechanical design, which is not limited to choosing legs spring stiffness only. The results presented here are derived by studying the stability of the passive dynamics of a quadruped robot running in the sagittal plane in a dimensionless context and might explain the success of simple, open loop running controllers on existing experimental quadruped robots. These can be summarised in (a) the self-stabilised behaviour of a quadruped robot for a particular gait is greatly related to the magnitude of its dimensionless body inertia, (b) the values of hip separation, normalised to rest leg length, and leg relative stiffness of a quadruped robot affect the stability of its motion and should be in inverse proportion to its dimensionless body inertia, and (c) the self-stable regime of quadruped running robots is enlarged at relatively high forward speeds. We anticipate the proposed guidelines to assist in the design of new, and modifications of existing, quadruped robots. As an example, specific design changes for the Scout II quadruped robot that might improve its performance are proposed.

scholarly journals Stable Balance Adjustment Structure of the Quadruped Robot Based on the Bionic Lateral Swing Posture

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jian-Hua Qin ◽  
Jie Luo ◽  
Kai-Chi Chuang ◽  
Tian-Syung Lan ◽  
Lie-Ping Zhang ◽  
...  
Keyword(s):  
Static Stability ◽  
Quadruped Robot ◽  
Experimental Simulation ◽  
Upright Posture ◽  
Design And Optimization ◽  
Generalized Coordinates ◽  
The Stability ◽  
Leg Kinematics ◽  
Peak Value ◽  
Robot Body

Aiming at the problem that the stability of the quadruped robot is decreased as its leg momentum is too high, a stable balance adjustment structure of the quadruped robot based on the bionic lateral swing posture is proposed. First, the leg structure of the quadruped robot is improved and designed by using the mechanism of the lateral swing posture of the leg of the hoof animal. Then, the D-H method is used to construct the corresponding leg kinematics model and determine the generalized coordinates of the leg joints in the lateral swing posture. The torque expression of the quadruped robot when it is tilted is established. Based on the differential equation of momentum of the hip joint and its static stability analysis, the static stability conditions in the upright posture and the bionic lateral swing posture are given. Finally, the experimental simulation and comparative analysis of the upright posture and the lateral swing posture of the quadruped robot are proposed by using the Adams virtual prototype technology. The simulation results show that as the angle of lateral swing increases, the peak value of the positive flip torque of the quadruped robot body increases accordingly, while the degree of tilt decreases accordingly, which shows that the bionic lateral swing posture of the quadruped robot has higher static stability than the traditional upright posture. This research provides a technical reference for the design and optimization of the offline continuous gait of the robot and the improvement of stability.

scholarly journals Static Gait Planning Method for Quadruped Robot Walking on Unknown Rough Terrain

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 177651-177660 ◽  
Author(s):  
Shuaishuai Zhang ◽  
Ming Liu ◽  
Yanfang Yin ◽  
Xuewen Rong ◽  
Yibin Li ◽  
...  
Keyword(s):  
Quadruped Robot ◽  
Planning Method ◽  
Rough Terrain ◽  
Gait Planning

Design of Vertebrae-Inspired Trunk Mechanism for Robust and Directive Quadruped Locomotion on Rough Terrain Without Requiring Sensing and Actuation

2017 ◽  
Vol 29 (3) ◽  
pp. 546-555 ◽  
Author(s):  
Takashi Takuma ◽  
◽  
Yoshiki Murata ◽  
Wataru Kase
Keyword(s):  
Rigid Body ◽  
Success Rate ◽  
Design Principle ◽  
Quadruped Robot ◽  
Rough Terrain ◽  
Elastic Coefficient ◽  
Sensors And Actuators ◽  
Quadruped Locomotion ◽  
Trunk Posture ◽  
Simulation Results

[abstFig src='/00290003/10.jpg' width='300' text='Quadruped robot equipping a vertebrae-inspired trunk mechanism' ] Quadrupedal animals adaptively change their trunk posture in order to avoid falling down and to facilitate directive locomotion even on rough terrain. This paper focuses on an animal-like trunk mechanism which has passive viscoelastic joints. The effect of the trunk mechanism is observed by changing the elasticity and configuration of joints. Simulation results showed that the locomotion success rate of a robot equipped with the trunk mechanism on rough terrain is higher than the locomotion success rate of a robot equipped with a rigid body. In addition, the distribution of the success rate changes according to the elastic coefficient, number, configuration, and type of joints. These results suggest a design principle for the trunk mechanism of a quadruped robot in order to obtain robust and directive locomotion without requiring sensors and actuators.

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