Latest Papers

ASME Journal of Mechanisms and Robotics

  • Integrated Wheel–Foot–Arm Design of a Mobile Platform With Linkage Mechanisms
    on March 20, 2024 at 12:00 am

    AbstractInspired by lizards, a novel mobile platform with revolving linkage legs is proposed. The platform consists of four six-bar bipedal modules, and it is designed for heavy transportation on unstructured terrain. The platform possesses smooth-wheeled locomotion and obstacle-adaptive legged locomotion to enhance maneuverability. The kinematics of the six-bar bipedal modules is analyzed using the vector loop method, subsequently ascertaining the drive scheme. The foot trajectory compensation curve is generated using the fixed-axis rotation contour algorithm, which effectively reduces the centroid fluctuation and enables seamless switching between wheels and legs. When encountering obstacles, the revolving linkage legs act as climbing arms, facilitating seamless integration of wheel, foot, and arm. A physical prototype is developed to test the platform on three typical terrains: flat terrain, slope, and vertical obstacle. The experimental results demonstrated the feasibility of the platform structure. The platform can climb obstacles higher than its own height without adding extra actuation.

Kinematic Performance and Static Analysis of a Two-Degree-of-Freedom 3-RPS/US Parallel Manipulator With Two Passive Limbs

Abstract

In this paper, a new 3-RPS (the limb consisting of one revolute, one prismatic, and one spherical joint)/US (universal joint and spherical joint) parallel mechanism with two degrees-of-freedom (DOFs) is obtained by adding a US passive limb into the 3-RPS parallel mechanism with the aim of obtaining a high load-bearing capacity. The moving platform possesses two rotational motions, analyzed by the Grassmann line geometry and screw theory. Then, the kinematic performance of the mechanism is analyzed, including inverse kinematics, overall Jacobian matrix, workspace, and singularity. On this basis, the mapping between the driving force and the load on the moving platform is deduced and verified by simulation. Next, the static of the proposed parallel mechanism is compared with that of the 3-RPS mechanism. The results show that the load-bearing capacity of the mechanism is improved by introducing the US passive limb. Finally, a case study verifies the potential application of the mechanism as a dual-axis tracking photovoltaic bracket.

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