Design of Planar 1-DOF Cam-Linkages for Lower-Limb Rehabilitation via Kinematic-Mapping Motion Synthesis Framework

Zhang

Proceedings of the Institution of Mechanical Engineers, Part C:

et al. 2021

In this paper, a cam-linkage mechanism with a swing follower with variable pivot has been studied. In this mechanism, the pivot of the swing follower is installed on a slider with an adjustable track direction, the follower performs a complex planar motion, and the motion range of the output angle can be adjusted according to the output requirements. In order to synthesize this mechanism, firstly, the relevant model is established and the basic structural parameters are optimized by considering the assembly conditions and the pressure angle under the limit position of the movement track of the follower mounting slider. Subsequently, the inverse method and the envelope theory are employed to derive the cam contour coordinates. Finally, the corresponding follower motion law is selected, the corresponding cam contour coordinates are calculated, and the entire cam contour curve is obtained using spline interpolation. An automatic design system for cam contours is developed. The processes are carried out through design examples and verified through motion simulations and prototype experiment. The present work can enrich the design theory of cam-linkage mechanisms.

Section: The Proposed Cam-linkage Mechanismmentioning

confidence: 99%

Section: The Proposed Cam-linkage Mechanismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Optimization and synthesis of a cam-linkage mechanism with a swing follower with variable pivot

Zhang

Proceedings of the Institution of Mechanical Engineers, Part C:

et al. 2021

IEEE Trans. Neural Syst. Rehabil. Eng.

“…Shao et al [12] designed a lower limb rehabilitation robot that required only constant-speed motors based on cam-linkages mechanism. Our group has also proposed kinematic-mapping-based approach to designed 1-DOF rehab mechanisms such as four-bar linkages for upper-limb rehab [13] and cam-linkages for lower-limb rehab [14]. However, a 1-DOF mechanism can only generate a unique trajectory, it might not suit well with different patients who have various body parameters.…”

Section: Introductionmentioning

confidence: 99%

Data-Driven Design of a Six-Bar Lower-Limb Rehabilitation Mechanism Based on Gait Trajectory Prediction

Song

Zhao

et al. 2023

For patients who need lower-limb kinetism rehabilitation training, this paper proposes an effective datadriven approach seeking the design of 1-degree-of-freedom (DOF) six-bar rehab mechanism through gait prediction by body parameters. First, gait trajectories from 79 healthy volunteers are collected along with their body parameters. Then, the normalized gait samples are clustered and regressed into a limited number of representative trajectories with K-means algorithm, and the cluster index is recorded as the label for each trajectory. Next, a genetic-algorithmoptimized support vector machine method is adopted to establish a classifier for the trajectories, obtaining the correspondence between body parameters and cluster labels of gait trajectories. As a result, once a group of body parameters are input into the classifier, the suitable gait trajectory can be predicted for the specific patient. A GA-BFGS algorithm is developed for 1-DOF six-bar mechanism synthesis and a GUI design software is presented that shows how the data-driven design process is realized. The novelty of this paper is using clustering and prediction technique to accomplish the patient-mechanism matching, so that simple, low-priced 1-DOF mechanisms could be adopted for large number of various patients without expensive customized design for each individual. In the end, a gait rehab device design example is provided, and a prototype device driven by a constant speed motor is presented, which illustrates the feasibility of the proposed method.

Optimization design of a bionic horse’s leg system driven by a cam-linkage mechanism

Liu

Zhang

Proceedings of the Institution of Mechanical Engineers, Part C:

et al. 2022

For equine-assisted therapy, a bionic horse configuration is presented. A bionic horse’s single leg system has two degrees of freedom (DOFs), which is driven by a cam-linkage mechanism and can adjust the leg’s endpoint trajectory. Based on analyzing the motion law of the bionic horse and the foot trajectory’s requirements of the leg system, a multi-objective optimization model is established based on the foot trajectory performance index. To determine the objective function, the errors between the ideal foot trajectory and the mechanism motion model’s foot trajectory, and the errors between the actual adjustable values and the target values for the motion range are taken as the optimization objective. In terms of the constraint conditions, the structural constraints, kinematic feasible region conditions, pressure angle requirements, et al., are considered. The ideal mechanism parameters are obtained by the intelligent optimization method. The results are verified by simulation modeling and experimental prototype, and the relevant ideas can provide a reference for the research of similar problems.