Fault tolerance criteria and walking capability analysis of a novel parallel-parallel hexapod break walking robot

Pan, Yang; Gao, Feng; Du, Hang

doi:10.1017/s0263574714001738

Cited by 9 publications

(6 citation statements)

References 30 publications

(30 reference statements)

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“…[1][2][3][4] An increasing amount of ground mobile devices based on parallel kinematics mechanism (PKM) legs have been launched out. [5][6][7] Employed in these robotic systems, the high-gain (stiff) position controller pushes the actuators to their torque limits for the position goal, which is unsuitable when a robot contacts the unstructured real-world ground. The impacts generated on the legs lead to harmful posture vibration or even unstable tipping.…”

Section: Introductionmentioning

confidence: 99%

Impedance control for a Stewart‐structure‐based wheel‐legged robotic system in wheel motion

Liu,

Wang,

Shi

2024

Intl J Robust & Nonlinear

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SummaryAn impedance control scheme is proposed for a Stewart‐structure‐based wheel‐legged robotic system to strengthen the dynamic attitude adjustment stability in wheel motion. The wheel‐leg, which is driven by electrical cylinders in the Stewart structure, is analyzed in kinematics and dynamics. The rotation in the axial direction of every electric cylinder is calculated to improve the accuracy of the kinematic model. To fulfill the impedance demands, a passive structure with 6 degrees of freedom (DOF) is modeled. The mass of the mechanism has a coupling effect on the impedance model for each DOF, which is a nonlinear function. As motion decoupling in the workspace has been completed for the Stewart structure, an impedance control strategy with inner‐loop position tracking is employed. An extended state observer (ESO) is designed to estimate the disturbances arising from the nonlinear coupling effects. Based on the ESO observation outputs, an active disturbance rejection control that explicitly handles the workspace limit is designed with guaranteed practical stability. By reducing force interaction and body vibration, the wheel‐legged robotic system keeps wheel motion stability on uneven roads. Multiple comparative experimental results are presented to validate the stability and effectiveness of the proposed method.

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Section: Introductionmentioning

confidence: 99%

Impedance control for a Stewart‐structure‐based wheel‐legged robotic system in wheel motion

Liu,

Wang,

Shi

2024

Intl J Robust & Nonlinear

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“…Sixlegged robots have a good performance in stability because they can use three or more legs to form a stable supporting triangle when walking. 2,3 As a result, the locomotion speed becomes a main issue for six-legged robots when the capability of the actuators are constrained.…”

Section: Introductionmentioning

confidence: 99%

Locomotion speed capability analysis of six-legged robots: Optimization and application

Chen

Tian

Gao

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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Locomotion speed is a key performance index of legged robots. However, methods to analyze and improve the locomotion speed capability are seldom developed, especially for six-legged robots. This paper develops a method to analyze and improve the omnidirectional walking speed and the turning speed of six-legged robots. The models of the inverse kinematics and the influence coefficients are built. Making use of the only-position-related property of the influence coefficients, a general optimization model of the locomotion trajectory is established. A two-step optimization method is introduced to solve the optimization problem. Based on the optimization, a comprehensive speed capability analysis is conducted on both omnidirectional walking and turning of the six-parallel-legged robot. The results clearly show the relationships among the speed capability, the walking direction and the duty cycle. The two-step optimization method improves the speed capability by 12.4%–13.2% for turning and 18.5%–20.5% for omnidirectional walking. Finally, the costs of the speed improvement are analyzed, including the stability, the energy consumption and the calculation time.

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“…Further, F. Gao and his team undertook a significant amount of research in this field. They deduced a fault tolerant criterion of a single broken leg and all leg fault combination types were analyzed using this criterion [16]. Residual mobility was analyzed using the screw theory in the case of a partial actuator fault, and a motion planning method based on a fault tolerance Jacobian matrix was proposed [17,18].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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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 tolerance criteria and walking capability analysis of a novel parallel-parallel hexapod break walking robot

Cited by 9 publications

References 30 publications

Impedance control for a Stewart‐structure‐based wheel‐legged robotic system in wheel motion

Impedance control for a Stewart‐structure‐based wheel‐legged robotic system in wheel motion

Locomotion speed capability analysis of six-legged robots: Optimization and application

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

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