Research On The Master-slave Control System Of Upper Limb Rehabilitation Robot

At present, rehabilitation robots in our country are still in the research step, and notmany of them are put into use. And also it is difficult to popularize because rehabilitationrobotics is a kind of integrated technology referring to mechanics, electrical engineering,automation, computer science and other subjects, its structure is generally morecomplicated and the robot is more costly. In this paper our aim is to develop a set of simpleand reliable control system of upper limb rehabilitation robot which can easily realize longdistance control.In order to easily realize long distance control, this control system consists of twoparts: the host computer and the slave computer. The host computer is used for sendingcontrol commands and for realizing the human-computer interface(HCI). The slavecomputer is used for recognizing, processing and executing the commands sent by the hostcomputer. Serial Communication Mode is adopted so that any equipment or device withserial port can send demands to the host computer, and the adoptability of the equipment ordevice is improved on different occasions.After the analysis and study of various controller, The MCU(Micro Controller Unit) isadopted as the controller of the slave computer. According to the characteristics ofrehabilitation training, the stepping motor is used as the driver. The control system mainlyimplements three kinds of control strategy: passive control, active control with auxiliaryforce and impedance control. The passive control means that the mechanical arm drives thepatient’s upper limb to do rehabilitation exercises according to the motion commands sentby the host computer. The active control with auxiliary force means that the mechanicalarm is driven to do rehabilitation exercises by the patient. Impedance control means that thepatient drives the mechanical arm to move while the mechanical arm blocks the movementof the patient with certain force at the same time.In this paper, the force sensor of the control system, which is used directly to measurethe force on the mechanical arm given by the human body, is fixed at the joints of themechanical arm and the upper limb in order to simplify the mechanism. In that way, boththe security is improved and the connection of the joints is also idealized. After theinformation gathered by the force sensor is amplified by the amplifying circuits, then it issent to the MCU which converts the signal from analog form into digital form (ADC) and then reads. The data control the change of position and the speed of the mechanicalarm according to the impedance control pattern built earlier, meanwhile, the patient’s limbcan be protected efficiently according to the level of the force detected by the force sensor.