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.

Light-Weight Design of Five-Degree-of-Freedom Hybrid Robot for Assembling in the Cabin

Abstract

Interior assembling inside the cabin of an aircraft requires assembling robot to be light-weight and able to carry heavy payload. This paper proposed a hybrid robot and carried out its optimal design and experiments. The robot consists of a 1T2R parallel module and a 2T serial module. In the parallel module, the first limb is composed of a slider crank mechanism and a RS link. The other two limbs are PRS limbs. Herein, R, S, P are revolute, spherical, and actuated prismatic joints. Optimization of the robot concerns motion/force transmissibility, total mass, and stiffness. Hence, kinematic, stiffness, and mass modeling are implemented, and then the Pareto-based multi-objective optimization. Objective arrangements are discussed by concerning (1) the conflicting relation between mass and the minimal linear stiffness along z-axis and (2) the overall stiffness performance. After comparing six multi-objective optimizations, it is found that simultaneously regarding mass and minimal linear stiffness along z-axis as objectives is beneficial for obtaining large payload-to-mass ratio, moreover having overall stiffness as objectives would lower the values of motion/force transmissibility and payload-to-mass ratio. Finally, optimization model having motion/force transmissibility, total mass, and minimal linear stiffness along z-axis as objectives is selected. The optimal payload-to-mass ratio is up to 13.2837. The five degrees-of-freedom hybrid robot is machined and assembled. Experiments on the workspace, repeatability, and load carrying capacity confirm the performances of the designed robot.

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