Kinematic stability evaluation method of a rigid-flexible lower limb gait rehabilitation training robot

Abstract

The invention provides a motion stability evaluation method of a rigid-flexible lower limb gait rehabilitation training robot, which combines the flexible cable tension, system stiffness, and pedal movement speed and rigid support of the rigid-flexible lower limb gait rehabilitation training robot. Chain B 1 It can comprehensively evaluate the stability of the rigid-flexible lower limb gait rehabilitation training robot, and provide a theoretical basis for the structural design, control strategy research and training task planning of the rigid-flexible lower limb gait rehabilitation training robot. It can effectively improve the safety of the training object.

Description

technical field [0001] The invention relates to a motion stability evaluation method of a rigid-flexible mixed lower limb gait rehabilitation training robot, which belongs to the field of stability research of rigid-flexible mixed robots. Background technique [0002] Since the rigid-flexible hybrid robot uses flexible cables as the driving element, rigid kinematic branch chains are introduced in order to expand its working space, which can obtain good maneuverability, but the kinematic stability of its end effector limits its practical application. Further development. [0003] Behzadipour S. et al. proposed to use the total stiffness matrix of the system to evaluate the stability of the system, but when establishing the system model, the flexible cable was simplified to a linear spring, which was too different from the actual flexible cable model, and the solution of the total stiffness of the system and the stability The calculation process is very demanding, and it is d...

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Problems solved by technology

[0002] Since the rigid-flexible hybrid robot uses flexible cables as the driving element, rigid kinematic branch chains are introduced in order to expand its working space, which can obtain good maneuverability, but the kinematic stability of its end effector limits its practical application. Further development

[0003] Behzadipour S. et al. proposed to use the total stiffness matrix of the system to evaluate the stability of the system, but when establishing the system model, the flexible cable was simplified to a linear spring, which was too different from the actual flexible cable model, and the solution of the total stiffness of the system and the stability The calculation process is very demanding, and it is difficult to quantitatively evaluate the kinematic stability of the system; Vijay Kumar’s research group uses the Hessian matrix to analyze the static stability of the cable-driven parallel robot system, and discusses the spatial configuration of the robot system. When the Hessian matrix eigenvalue When both are positive, the motion of the robot system is stable, but the influence of the cable tension on the motion stability of the end effector is not considered; Bosscher P. et al. proposed a method based on the slope of the motion screw to evaluate the cable The motion stability of the parallel robot can quantitatively evaluate the motion stability of the system, but the influence of the flexible cable tension on the motion stability of the end effector has not been considered; Liu Peng et al. In the study, considering two factors such as the position of the end effector and the tension distribution of the cables, the stability and evaluation methods of the system were defined. actuator, but the performance factor of the flexible cable tension is defined from two directions, the horizontal direction and the vertical direction, which cannot fully evaluate the motion stability of the robot; Zhao Zhigang, Wang Yanlin and others proposed to use the Krasovsky method and the The mixed method of force, pose and posture evaluates the stability of the flexible cable-driven parallel robot, and gives the stability evaluation index, but does not consider the influence of the system stiffness and the motion speed of the end effector on the system stability; Yang Jian et al. The stability of the end effector with three linear degrees of freedom at the end is evaluated by combining the two factors of cable tension and system stiffness, but the proposed performance factor is only defined from the level of the entire workspace, and does not consider the current state pull force and system stiffness The impact on motion stability; patents ZL201711047293.9 and ZL201710372517.7 both evaluate the motion stability of a parallel robot without rigid motion branch chains based on the cable tension, the position and posture of the end, but do not consider the system stiffness and rigidity Influence of Motion Velocity of Kinematic Branch Chain on the Stability of Parallel Robot

[0004] In the above literature, different methods are used to discuss the stability of the system, but the considerations are single and not comprehensive enough; due to the existence of rigid branch chains in the rigid-flexible lower limb rehabilitation training robot, the rigid branch chains can be well eliminated The influence of the position of the foot pedal on the stability of the movement; but the existence of the rigid branch chain introduces another factor that affects the stability of the movement. The stability of the rigid-flexible lower limb rehabilitation training robot depends on the structural parameters, configuration parameters and Control algorithm, there is a close relationship among the three, and they influence each other; but for now, the motion stability of the rigid-flexible lower limb rehabilitation training robot is related to the tension constraint of the flexible cable, the stiffness of the system, the pedals and the rigid branch chain. The display mathematical expression between the movement speed needs to be further improved

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