scholarly journals Fault-Tolerant Tripod Gait Planning and Verification of a Hexapod Robot

2020 ◽  
Vol 10 (8) ◽  
pp. 2959
Author(s):  
Yiqun Liu ◽  
Xuanxia Fan ◽  
Liang Ding ◽  
Jianfeng Wang ◽  
Tao Liu ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Fault Tolerant ◽  
Kinematic Model ◽  
Stability Margin ◽  
The Body ◽  
Hexapod Robot ◽  
Gait Planning ◽  
Phase Sequence ◽  
Gait Phase ◽  
Tripod Gait

In some hazardous or inaccessible applications, such as earthquake rescue, as a substitute for mankind, robots are expected to perform missions reliably. Unfortunately, the failure of components is difficult to avoid due to the complexity of robot composition and the interference of the environment. Thus, improving the reliability of robots is a crucial problem. The hexapod robot has redundant degrees of freedom due to its multiple joints, making it possible to tolerate the failure of one leg. In this paper, the Fault-Tolerant Tripod (F-TT) gait dealing with the failure of one leg is researched. The Denavit–Hartenberg (D-H) method is exploited to establish a kinematic model for the hexapod robot, the Jacobian matrix is analyzed, and it is proved that the body can be controlled when three legs are supported. Then, an F-TT gait phase sequence planning method based on a stability margin is established, and a method to improve stability is proposed. The trajectory for the center of gravity (COG) and foot is studied. Finally, a simulation model and prototype robot experiments are developed, and the effectiveness of the proposed method is verified.

Fault-tolerant crab gaits and turning gaits for a hexapod robot

Robotica ◽  
2005 ◽  
Vol 24 (2) ◽  
pp. 269-270 ◽  
Author(s):  
Jung-Min Yang
Keyword(s):  
Stride Length ◽  
Fault Tolerant ◽  
Stability Margin ◽  
Hexapod Robot ◽  
Joint Failure ◽  
Gait Planning

This paper studies crab gaits and turning gaits of a hexapod robot with a locked joint failure. Due to the reduced workspace of a failed leg, fault-tolerant gaits have limitations in their mobility. Based on the principles of fault-tolerant gait planning, periodic crab gaits and turning gaits are proposed in which a hexapod robot carries out tripod walking after a locked joint failure, having a reasonable stride length and stability margin.

scholarly journals Hybrid Gait Planning of A Hexapod Robot

2020 ◽  
Vol 4 (2) ◽  
pp. 11
Author(s):  
Ruyi Wang
Keyword(s):  
The Body ◽  
Comparative Experiment ◽  
Body Structure ◽  
Hexapod Robot ◽  
Gait Patterns ◽  
Gait Planning ◽  
Tripod Gait

The adapotation of gaits pattern is a basic and important for the hexapod robot to move stably and efficiently, which depends on the servos of the robot’s legs, and also the body structure of the robot.This paper compares the tripod gait and the crab-inspired gait for a specific hexapod to move forward and move backward; turn left and turn right and integrates the two gaits to apply them under different conditions. The hexapod has three servos on each legs, thus the freedom level of each leg is three-degree. From the comparative experiment, this two gait patterns are suitable for different turning demands.

Dynamic Modeling and Control of the Hexapod Robot Using Matlab SimMechanics

2018 ◽  
Author(s):  
Sameh I. Beaber ◽  
Abdelrahman S. Zaghloul ◽  
Mohamed A. Kamel ◽  
Wessam M. Hussein
Keyword(s):  
Dynamic Modeling ◽  
Kinematic Model ◽  
Inverse Kinematic ◽  
Legged Robot ◽  
Hexapod Robot ◽  
Modeling And Control ◽  
Robot Trajectory ◽  
Tripod Gait ◽  
Inverse Kinematic Analysis ◽  
And Control

This paper presents a detailed dynamic modeling of phantom ax12 six-legged robot using Matlab SimMechanics™. The direct and inverse kinematic analysis for each leg has been considered in order to develop an overall kinematic model of the robot. Trajectory of each leg is also considered for both swing and support phases when the robot walks with tripod gait in a straight path. Newton-Euler formulation has been utilized to determine the joint’s torque. These results were verified using SimMechanics™. Also, feet force distributions of the hexpaod are estimated via SimMechanics™, which is necessary for its control.

scholarly journals A Design Concept and Kinematic Model for a Soft Aquatic Robot with Complex Bio-mimicking Motion

2022 ◽  
Author(s):  
Shokoofeh Abbaszadeh ◽  
Roberto Leidhold ◽  
Stefan Hoerner
Keyword(s):  
Degrees Of Freedom ◽  
Kinematic Model ◽  
The Body ◽  
Optical Measurements ◽  
Fish Mortality ◽  
Entire Body ◽  
Animal Testing ◽  
Live Animal ◽  
Complex Deformation ◽  
Propulsion Performance

AbstractFish mortality assessments for turbine passages are currently performed by live-animal testing with up to a hundred thousand fish per year in Germany. A propelled sensor device could act as a fish surrogate. In this context, the study presented here investigates the state of the art via a thorough literature review on propulsion systems for aquatic robots. An evaluation of propulsion performance, weight, size and complexity of the motion achievable allows for the selection of an optimal concept for such a fish mimicking device carrying the sensors. In the second step, the design of a bioinspired soft robotic fish driven by an unconventional drive system is described. It is based on piezoceramic actuators, which allow for motion with five degrees of freedom (DOF) and the creation of complex bio-mimicking body motions. A kinematic model for the motion’s characteristics is developed, to achieve accurate position feedback with the use of strain gauges. Optical measurements validate the complex deformation of the body and deliver the basis for the calibration of the kinematic model. Finally, it can be shown, that the calibrated model presented allows the tracking of the deformation of the entire body with an accuracy of 0.1 mm.

Design and Analysis of a Smart Rehabilitation Walker With Passive Pelvic Mechanism

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Jiancheng (Charles) Ji ◽  
Shuai Guo ◽  
Fengfeng (Jeff) Xi ◽  
Leigang Zhang
Keyword(s):  
Degrees Of Freedom ◽  
Force Feedback ◽  
Kinematic Model ◽  
The Body ◽  
Community Based ◽  
Community Based Rehabilitation ◽  
Left And Right ◽  
Increasing Demand ◽  
Limb Rehabilitation ◽  
Motion Intention

Abstract In response to the ever-increasing demand of community-based rehabilitation, a novel smart rehab walker iReGo is designed to facilitate the lower limb rehabilitation training based on motion intention recognition. The proposed walker provides a number of passive degrees-of-freedom (DoFs) to the pelvis that are used to smooth the hip rotations in such a way that the natural gait is not significantly affected, meanwhile, three actuated DoFs are actively controlled to assist patients with mobility disabilities. The walker first identifies the user’s motion intention from the interaction forces in both left and right sides of the pelvis and then uses the kinematic model to generate appropriate driving velocities to support the body weight and improve mobility. In this paper, workspace, dexterity, and the force field of the walker are analyzed based on the system Jacobian. Simulation and experiments with healthy subjects are carried out to verify the effectiveness and tip-over stability. These results demonstrate that the walker has sufficient workspace for pelvic motions, satisfactory dexterity, and near-linear force feedback within the prescribed workspace, and that the walker is easily controlled to ensure normal gait.

scholarly journals Dynamic simulation and design of a simple hexapod robot

2020 ◽  
Vol 13 (36) ◽  
pp. 3801-3819
Author(s):  
Naif Khalaf Al-Shammari ◽  
Keyword(s):  
Mechanism Design ◽  
Kinematic Model ◽  
Natural Environments ◽  
Hexapod Robot ◽  
Analysis Method ◽  
Remote Areas ◽  
Physical Prototype ◽  
Tripod Gait ◽  
Walking Mechanism ◽  
And Control

Background/Objectives: For motions in off-road navigation, including sandy or wet natural environments and space explorations legged machines, mimicking anatomy of legged animals are efficient. However, the traditional full-actuated legged robots are heavy with complex actuation and control systems, as for each degree of freedom separate actuator is used. The purpose of this work is to develop a kinematic model using a single-actuator for hexapod legged robot taking advantage of bio-inspiration and mechanism design techniques. Methods/Statistical analysis: A vector analysis method was used for measuring the system kinematics equations. The simulation of the walking process was performed using MATLAB. A real prototype of the system has been fabricated based on the design, which is not bulky due to use of single motor, and does not require complex control and sensor systems. Findings: Simulations showed that the kinematic model along with the hypothesis on the ground interaction describes the locomotion, which can be used where robots with low-speed repositioning are required. Theoretical analysis, virtual prototype simulations, as well as initial experiments with the physical prototype, showed an efficient functionality of the system. Novelty/Applications: The design and kinematic model can be used for developing low-energy environmental robots for remote areas with occasional relocation requirements. Keywords: Biomimetic environmental robot; kinematic analysis; mechanism design; tripod gait; walking mechanism

Posture Synthesis and Control of a Symmetric Hexapod Robot on Corrugated Surfaces for Underwater Observation

2007 ◽  
Author(s):  
Xin Wu ◽  
Yaoyu Li ◽  
Thomas R. Consi
Keyword(s):  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Ccd Camera ◽  
The Body ◽  
Hexapod Robot ◽  
Corrugated Surfaces ◽  
Sensor Platform ◽  
Robotic Leg ◽  
And Control

This paper presents the first stage of a project to develop a six-legged walker (hexapod) as a highly stable mobile sensor platform for in situ benthic observation. The hexapod is radially symmetric with a downward looking, CCD camera-coupled, microscope mounted co-linear with the central axis of the body. A Lynxmotion (Peoria, IL) Model EH-3R radially symmetric 18 degrees-of-freedom hexapod robot has been used for initial land-based experiments and simplified to a 12 degree-of-freedom structure by locking the panning joint of each leg. Forward and inverse kinematics are then used to derive the relationship between the body posture and the proximal and distal joint angles on legs, which is the basis of the microscope’s coarse focusing for the observation. The kinematics analysis has been verified with both Matlab-based simulations and experiments on the hexapod prototype. Finally, passivity-based posture control is developed and simulated based on the inverse dynamics of the robotic leg.

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.

scholarly journals The gait planning of hexapod robot based on CPG with feedback

2020 ◽  
Vol 17 (3) ◽  
pp. 172988142093050 ◽  
Author(s):  
Binrui Wang ◽  
Ke Zhang ◽  
Xuefeng Yang ◽  
Xiaohong Cui
Keyword(s):  
Central Pattern Generator ◽  
Stability Margin ◽  
Pattern Generator ◽  
The Body ◽  
Middle Level ◽  
Point Problem ◽  
Vector Product ◽  
Hexapod Robot ◽  
The Stability ◽  
The Relationship

To realize the omnidirectional motion, the transition motion of hexapod robot from flat to slope is studied, and a new type of stability criterion is proposed. Firstly, the landing point problem of the hexapod robot in the process of transition is studied, the relationship between the introduced angle in ankle of the supporting leg and the body pitch is acquired, and the transition gait based on central pattern generator bottom feedback is planned. Secondly, the slope motion is analyzed, the relationship between the angle variable of the supporting knee joint and the pitch angle of hexapod is obtained, and the slope gait is planned based on central pattern generator middle level feedback. According to vector product, the solution of working out the stability margin of hexapod robot’s motion is designed. Lastly, MATLAB/ADAMAS co-simulation platform and physical hardware are constructed, the simulation and experiment of transition motion of hexapod robot from flat to 12° slope and motion of climbing 16° slope are done. According to the analysis of the results, in the transition motion from flat to 12° slope, based on the transition gait, hexapod robot can keep three foots touch the ground, and the foot force is uniform. According to the means designed to work out a stability margin based on vector product, the stability margin constant is greater than zero. In the motion of climbing 16° slope, based on the slope gait, hexapod robot completes the motion of climbing 16° slope. Based on transition gait, hexapod robot implements the transition movement from flat to slope stably. Based on slope gait, hexapod robot improves the ability of slope motion.

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