Latest Papers

ASME Journal of Mechanisms and Robotics

  • A Small-Scale Integrated Jumping-Crawling Robot: Design, Modeling, and Demonstration
    on June 16, 2025 at 12:00 am

    AbstractThe small jumping-crawling robot improves its obstacle-crossing ability by selecting appropriate locomotion methods. However, current research on jumping-crawling robots remains focused on enhancing specific aspects of performance, and several issues still exist, including nonadjustable gaits, poor stability, nonadjustable jumping posture, and poor motion continuity. This article presents a small jumping-crawling robot with decoupled jumping and crawling mechanisms, offline adjustable gaits, autonomous self-righting, autonomous steering, and certain slope-climbing abilities. The crawling mechanism adopts a partially adjustable Klann six-bar linkage, which can generate four stride lengths and three gaits. The jumping mechanism is designed as a six-bar linkage with passive compliance, and an active clutch allows energy storage and release in any state. The autonomous self-righting mechanism enables the robot to self-right after tipping over, meanwhile providing support, steering, and posture adjustment functions. Prototype experiments show that the designed robot demonstrates good motion stability and can climb a 45 deg slope without tipping over. The robot shows excellent steering performance, with a single action taking 5 s and achieving a steering angle of 11.5 deg. It also exhibits good motion continuity, with an average recovery time of 12 s to return to crawling mode after a jump. Crawling experiments on rough terrain demonstrate the feasibility of applying the designed robot in real-world scenarios.

A Screw Theory Approach for Instantaneous Kinematic Analysis of Parallel–Serial Manipulators

Abstract

The paper presents an approach to perform an instantaneous kinematic analysis of parallel–serial (hybrid) manipulators using screw theory. In this study, we focus on non-kinematically redundant manipulators that include a single parallel mechanism. The proposed systematic procedure allows deriving Jacobian matrices for such manipulators, which provide mathematical relations between the end-effector velocities and speeds in the actuated joints. A generalized structure of the obtained matrices also reflects the constrained motions of the end-effector and the parallel mechanism. To illustrate the developed techniques, we consider three examples where we analyze three well-known parallel–serial manipulators with six, five, and four degrees-of-freedom. Following the proposed method, we determine Jacobian matrices for each manipulator. Next, we apply the presented approach for velocity analysis of a novel parallel–serial manipulator with five degrees-of-freedom. Numerical simulations validate the proposed theoretical techniques. The suggested approach represents the basis for subsequent singularity and performance analysis, and it can be adapted to hybrid manipulators with other architectures.

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