Fault-Tolerant Gait Planning for a Hexapod Robot Walking over Rough Terrain

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.

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

Robotica ◽

10.1017/s0263574705002237 ◽

2005 ◽

Vol 24 (2) ◽

pp. 269-270 ◽

Cited By ~ 16

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.

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Gait Planning and Control of Hexapod Robot Based on Velocity Vector

10.1109/icarm52023.2021.9536055 ◽

2021 ◽

Author(s):

Junfeng Xue ◽

Jiehao Li ◽

Zhihua Chen ◽

Shoukun Wang ◽

Junzheng Wang ◽

...

Keyword(s):

Velocity Vector ◽

Hexapod Robot ◽

Gait Planning ◽

Planning And Control ◽

And Control

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Deviation from the direction of motion across gaits in a hexapodal robot

Industrial Robot the international journal of robotics research and application ◽

10.1108/ir-03-2019-0054 ◽

2020 ◽

Vol 47 (3) ◽

pp. 325-333

Author(s):

Zijie Niu ◽

Aiwen Zhan ◽

Yongjie Cui

Keyword(s):

Design Methodology ◽

Planning Method ◽

Hexapod Robot ◽

Acceleration Sensor ◽

Forward Motion ◽

Gait Planning ◽

Content Type ◽

Cargo Handling ◽

Subsequent Research ◽

Experimental Errors

Purpose The purpose of this study is to test a chassis robot on rugged road cargo handling. Design/methodology/approach Attitude solution of D-H series robot gyroscope speed and acceleration sensor. Findings In identical experimental environments, hexapodal robots experience smaller deviations when using a four-footed propulsive gait from a typical three-footed gait for forward motion; for the same distance but at different speeds, the deviation basically keeps itself within the same range when the robot advances forward with four-foot propulsive gait; because the foot slide in the three-footed gait sometimes experiences frictions, the robot exhibits a large gap in directional deviations in different courses during motion; for motion using a four-footed propulsive gait, there are minor directional deviations of hexapodal robots resulting from experimental errors, which can be reduced through optimizing mechanical structures. Originality/value Planning different gaits can solve problems existing in some typical gaits. This article has put forward a gait planning method for hexapodal robots moving forward with diverse gaits as a redundant multifreedom structure. Subsequent research can combine a multiparallel-legged structure to analyze kinematics, optimize the robot’s mechanical structure and carry out in-depth research of hexapod robot gaits.

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Research on the Posture Control Method of Hexapod Robot for Rugged Terrain

Applied Sciences ◽

10.3390/app10196725 ◽

2020 ◽

Vol 10 (19) ◽

pp. 6725

Author(s):

Yubin Liu ◽

Chunbo Wang ◽

He Zhang ◽

Jie Zhao

Keyword(s):

Control Method ◽

Posture Control ◽

Rough Terrain ◽

Maintenance Strategy ◽

Hexapod Robot ◽

Rugged Terrain ◽

Foot Force ◽

Adjustment Strategy ◽

Posture Maintenance ◽

Posture Adjustment

This paper proposes a hexapod robot posture control method for rugged terrain to solve the problem of difficulty in realizing the posture control of a foot robot in rough terrain. The walking gait and original position of a six-legged robot is planned, and the Layer Identification of Tracking (LIT) strategy is developed to enable the robot to distinguish mild rugged terrain and severe rugged terrains automatically. The virtual suspension dynamic model is established. In mild rugged terrain, the posture maintenance strategy is adopted to keep the stability of the torso. In severe rugged terrain, the posture adjustment strategy is adopted to ensure the leg workspace and make it more widely adapt to the changing terrain, and a gravity center position adjustment method based on foot force distribution is designed to use foot force as feedback to control the position and attitude. The experiment of posture control in rough terrain and climbing experiment in the ladder terrain shows that the hexapod robot has good posture maintenance and posture adjustment effects when traversing complex terrain through the posture maintenance strategy and the posture adjustment strategy. Combined with the terrain identification method based on LIT, the hexapod robot can successfully climb the ladder terrain through the identification of the changing ladder terrain, and the movement of the posture adjustment process is stable.

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Biologically based distributed control and local reflexes improve rough terrain locomotion in a hexapod robot

Robotics and Autonomous Systems ◽

10.1016/0921-8890(96)00003-6 ◽

1996 ◽

Vol 18 (1-2) ◽

pp. 59-64 ◽

Cited By ~ 118

Author(s):

Kenneth S. Espenschied ◽

Roger D. Quinn ◽

Randall D. Beer ◽

Hillel J. Chiel

Keyword(s):

Distributed Control ◽

Rough Terrain ◽

Hexapod Robot

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Compliant Walking Control for Hydraulic Driven Hexapod Robot on Rough Terrain

Journal of Robotics and Mechatronics ◽

10.20965/jrm.2011.p0149 ◽

2011 ◽

Vol 23 (1) ◽

pp. 149-162 ◽

Cited By ~ 22

Author(s):

Addie Irawan ◽

◽

Kenzo Nonami ◽

Keyword(s):

Large Scale ◽

Rough Terrain ◽

Vertical Force ◽

Hexapod Robot ◽

Actual System ◽

Step Motion ◽

Motion Signal ◽

Decision Control ◽

Compliant Control ◽

Kinematic Motion

This article describes the proposed force-based walking method for hydraulically driven hexapod robot named COMET-IV, to walk on the large scale rough terrain. The trajectory is designed where foot step motion for each leg is decided by vertical force on the foot that is calculated from cylinder torque of thigh and shank. This proposed walking trajectory is established with compliant control strategy, which consists of force control based on position range from the trajectory motion signal. This force controller is dynamically control ON/OFF by proposed decision algorithms that derived from the changes of kinematic motion of the trajectory itself. In addition logical attitude (body) control is designed as a part of the decision control module that makes a pre-calculation of decision making based on leg sequence changes. For more stability dynamic swings raising control is derived from trajectory equations to perform a different degree of swing rising for each leg when the robot stepping on the different level of terrain. All proposed controllers are verified in the COMET-IV actual system with walking on the designed rough terrain platform consists of random levels of hard bricks and rubber pads.

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