A Simplified Inverse Dynamics Modelling Method for a Novel Rehabilitation Exoskeleton with Parallel Joints and Its Application to Trajectory Tracking

Qianqian Fang,Hegao Cai,Yanhe Zhu,Ge Li,Jie Zhao,Tian Xu

doi:10.1155/2019/4602035

Qianqian Fang, Hegao Cai + Show 4 more

Open Access

https://doi.org/10.1155/2019/4602035

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Abstract

In this paper, a new modular upper limb rehabilitation exoskeleton, which is actuated by a parallel mechanical structure, is designed to help stroke patients. For analysing the relationship between motor torque and joint torque of the novel exoskeleton, a conversion algorithm mapping motor motion to joint motion is developed here. Then, to simplify the dynamics model of exoskeleton with parallel actuated joints, the serial equivalence configuration dynamics of the exoskeleton is established to be equivalent to the parallel joints dynamics. Afterwards, a torque controller used for our exoskeleton is designed based on the proposed conversion algorithm and the inverse dynamics of exoskeleton. It should be noted that the controller mentioned above combines both conversion algorithm and joint position decoupling. At last, for verifying the effectiveness of the proposed algorithms, a trajectory tracking simulation is given, and the simulated results show the proposed algorithms are valid.

Highlights

Stroke is a neurological disease with a high prevalence and often leads to disability
We designed a 6DOF modular cable-driven upper limb rehabilitation exoskeleton robot with parallel actuated joints based on human anatomy and biological principles to overcome the above limitations. e overall structure of the exoskeleton can be moved and fixed on any bracket which makes it compact and simple. e exoskeleton consists of three independent modules representing three joints of the human upper limb, and each module achieves two DOFs of the human upper limb. e structure can contribute to both a single joint and multijoint rehabilitation training for patients
The simulation results prove the validity of the proposed algorithms. e main contributions of this paper are as follows: (1) By converting motion relationship between motors and joints of the designed exoskeleton, the parallel exoskeleton is equivalently simplified to a serial exoskeleton to establish inverse dynamics; (2) a novel parallel upper limb rehabilitation exoskeleton with modular structure was designed; (3) a trajectory tracking control method for the exoskeleton was designed based on the proposed conversion algorithm of equivalent simplified inverse dynamics

Summary

Introduction

Stroke is a neurological disease with a high prevalence and often leads to disability. We designed a 6DOF modular cable-driven upper limb rehabilitation exoskeleton robot with parallel actuated joints based on human anatomy and biological principles to overcome the above limitations. E main contributions of this paper are as follows: (1) By converting motion relationship between motors and joints of the designed exoskeleton, the parallel exoskeleton is equivalently simplified to a serial exoskeleton to establish inverse dynamics; (2) a novel parallel upper limb rehabilitation exoskeleton with modular structure was designed; (3) a trajectory tracking control method for the exoskeleton was designed based on the proposed conversion algorithm of equivalent simplified inverse dynamics. E paper is organized as follows: Section 2 is the mechanical design of the 6-DOF upper limb rehabilitation exoskeleton based on parallel actuated joints. For more structural design details, one can refer to our previous work [33, 34]

The Proposed Conversion Algorithm

Trajectory Tracking Control and Simulations

Discussion

Conclusion