Upper Limb Rehabilitation Robot Tendon-sheath Transmission Characteristics And Motion Control

Rehabilitation robot actuator design is conciser and lighter with certain flexibility. At thesame time, according to the rehabilitation movement characteristics (low speed and variable load,buffer, etc.), the appropriate drive systems is selected. However, the arm joint applied to industrialrobots or special environment of mechanical arm is widely used with motor, gear reducer, orconnected with the transmission system of the joint shaft directly. The agency above need motorand gear reducer to be installed near the mechanical arm joint, which increases the demand forpower and drive components,overalls weight and volume,cost,the internal consumption, andreduces the mechanical arm isothermal ability and efficiency. In accordance with the principle of"the lightest weight, the maximum load capacity", the tendon-sheath transmission is one of themost prominent mechanical structures of mechanical arms to make various improvements.Therefore, the application of tendon-sheath transmission in rehabilitation robot system research isof great value in application and theory research.In accordance with the summary of the domestic and foreign research achievements oftendon-sheath transmission technology, the tendon-sheath transmission system is designed toapply for the rehabilitation robot, then the performance of the transmission is studied,it is followedas:The static model is built based on the tendon-sheath transmission system.After the analysis ofinteraction relationship between the tendon and the sheath, it shows that the transmissioncharacteristics are determined by the coefficient of friction between the tendon and the sheath,thetransmission system’s space pose, the tendon-sheath system’s space position etc., and that theinput-output relationship of the transmission system is nonlinear.The transmission system’s special pose is analyzed by finite element method analysis, whichmainly includes the structure and material of the sheath, location constraints of the sheath (such asspace constraint, freedom degree, direction constraint) etc,and the wiring line of the transmissionsystem is proposed.And the sum of circular arc section of central angle is solved.Through the analysis of the institutions of upper limbs rehabilitation robot, the wiring line isset up..Then based on the sheath space pose analysis, the sheath length is determined at last.In this paper, there is a comprehensive introduction made about the correct selection and useof the tendon, sheath, material selection, installation and maintenance, the selection of sheath endfixed way. Then, the tendon and sheath required is selected preliminarily. The tendon minimumradius() of curvature that will meet the requirement is solved. Above that is provided for thestructural parameters of the tendon-sheath transmission system.The tendon-sheath transmission experiment platform is set up, which measures the coefficient of friction of the tendon-sheath transmission, and it’s proved that force characteristicsof the formula deduced is correct. The radius of curvature has a significant impact on the sheathbending stress,and that it is feasible simulation method to calculate the sum of the correspondingunit circular arc segment central angle. Quantitative analysis of tendon-sheath transmission systemhas been carried on.Finally, some motion control experiments have been done.It shows thatdifferent training patterns with the transmission system can be realized.