Research On Safe TCM Massage Robotic Arm System And Its Control Stategy

With the advance of the living standard, the demand of traditional Chinese medical massage is growing rapidly. Qualified doctor, however, can not meet the ever growing demand, which result in serious imbalance of the ratio between patients and doctors, and thus render the acute contradiction of providers and customers. Now this contradiction has become one of the social problems that should be solved immediately. As the characteristic of high positioning accuracy, high intelligence and inexhaustibility, robot is a good device to realize active massage therapy and it is also one of the most effective methods to achieve massage therapy automatically. Due to the intensive support to the research of massage robot given by the government, relative technologies of massage have been becoming a focus of attention in recent years. The research of traditional Chinese medicine(TCM for short) massage robot started rather late in China. Although having acquired general achievements, commercialization and marketization can not be indeed achieved, due to the doubt of its safety,effective and acceptable.Massage robot need to work with human by physical contact, thus, the safety of the robot is very important. In order to develop human-friendly massage robot, the robot system should be designed with novel approach. This paper is supported by the National Natural Sciences Foundation of China entitled ‘Dynamic and compliant control of dual–arm of humanoid robotic’, Plan of Beijing Technology New Star titled ‘Research on biomechanics theory of TCM and massage robot’ and the project of Beijing Technology Committee titled ‘Research on press manipulation of TCM massage robot aimed at pain of waist’. A prototype of robot is developed in this paper, which can do safe and effective TCM massage jobs. The mechanism, modeling and control scheme of this robot are discussed with details in this paper. The main works of this paper include:1. Combined with the technical requirements of massage robot, the platform of TCM robot is designed and built. The design of mechanism, the design of hardware circuit, implemention of control system and establishment of security system are introduced in detail in this paper.2. A new kind of modular mechatronics flexible-joint is proposed. An elastic unit is assembled into inner structure of the joint. The key advantages of using elastic unit are:(a) The joint may achieve the goal of buffering force;(b) The security is guaranteed while human body is contacted to. The system realizes torque closed-loop control by applying elastic unit, resulting in low rotor inertia, so that the output of robot takes on a quality of low impedance. Moreover, the structure is lightweight and high-powered by adopting mature design principles. As a result, the disadvantaged influence caused by the linkages inertia is effectively reduced, so that the security is improved. Besides, the strength of critical components is calibrated through finite element method.3.The mathematical model of the robot body and the dynamic model during robotic massage process are built based on detailed analysis. In the aspect of mathematical model for robot body, the direct and inverse kinematics and the workspace is computed. And dynamics of manipulator is discussed according to the Newton-Euler iteration method. Then, the robot capability is validated by simulation. In the aspect of dynamic model during massage process, the problem of dynamic modeling about robotic friction process is solved based on port-Hamilton theory. In this paper, port-based modeling approach imported, the dynamic models of human and robot are established separately using structure of Dirac and theory of Hamilton. And human viscoelastic model and friction model brought by robot interaction are estabilished and discussed. Finally, the dynamic model of massage process is described accurately.4. Based on the dynamics model of the robot, the control system is designed, and the safety control strategy in the robot work is studied. On one hand, impedance control system of the robot is studied. The problem of robotic coupling stability during the interaction between robot and human is analyzed by passivity-based theroy. On the other hand, the reaction mechanisms are studied in this paper and the location and detection about physical interaction is implemented according to the iteraction function and interaction recognition vector proposed in this paper. Furthermore, safety massage control strategy and safety massage controller of robot are designed.5. Two experimental platforms of the robot based on integrated flexible joint and Chinese medicine massage are established and the physical experiments are conducted on these platforms. The concrete researches including following several aspects: the mechanical parameters acquisition of massage manipulation; the experimental research on robotic feature; the validation experiments of robotic security and massage effectiveness. The experimental results indicate that the robot could effectively replicate three kinds massage manipulation in safety including pressing, rubbing and plunking, It proved that the safe TCM robotic arm system designed in this paper can satisfy the TCM requirements.Research and discussion of construction of system of TCM massage robot, modeling of TCM massage robot and passivity-based control strategy established the foundation of further research on massage robot. In addition, the results of this paper can provide theoretical support for marketlization.