Exoskeleton Based Man Machine Intelligent System And Its Application

The exoskeleton-type system is a kind of man-machine system centered by human.It is always designed as an external mechanical structure whose joints correspond to those of human body or limbs.It combines the human intelligence and the machine power so that it enhances the intelligence of the machine and the power of the human operator.As a result,the human operator can achieve what he is not capable of by himself.Robot tele-operation and human power augmentation are its two prominent applications.In recent years,the exoskeleton-type systems have been developed rapidly accompanied with great achievements in mechanical and electronic engineering,automation technology,biological,and material science.This reveals that the exoskeleton-type systems have a nice prospect for daily-life application and significance in science research.The work of this paper is to provide a comprehensive discussion of the exoskeleton-type system on the viewpoint of man-machine system.The wearability is the main characteristic of the exoskeleton-type system.The structure of exoskeleton should be anthropomorphic and ergonomic,not only in shape but also in function and in the distribution of the DOF as well.Due to identity motion between the human operator and the exoskeleton,the kinematic model of the exoskeleton-type system can be described by D-H method. By investigating the atlas of the human upper limb during motion,the biomechanical model of human upper-limb can be established.3RPS parallel mechanism was introduced to realize the 3-DOF motion of human shoulder,which excellently promised to track the human upper-limb motion.According to the DOF distribution and anatomy of human lower-extremity,a 4-DOF lower-limb exoskeleton was developed on the linear actuator composed by DC motor and ball-screw.A 5-link kinematic and dynamic model was set up based on the human gait.In order to guarantee the safety and comfort of the exoskeleton-type system,the support were designed to adapted to the morphology of human limb,thus avoiding misalignments between exoskeleton and limb.In addition,the general safety can be evaluated by employing the critical impact force as a minimal impact force that causes injury to humans and giving the definition of danger index as the producible impact force against the critical impact force.Definitely,the impact force can be minimized by means of reducing the mass and inertia of the moving part,using distributed macro-mini actuation and joint compliance,and mounting stop block.Basically,the control architecture of exoskeleton-type systems is quite different from the traditional intelligent robotics.In this control architecture,the human operator is not only the commander or the supervisor of the system,but also a part in the control loop,called 'man-in-the-loop'.This is intuitive that the human operator receives the feedback from environments and optimizes the control target.It puts more emphasis on the combination of the human intelligence and machine power,and their information exchanging,so that the man and the exoskeleton are coupled together and both are irreplaceable.The force feedback control strategy for upper-limb and intelligent control strategy for lower-limb exoskeleton,including passive control, semi-active control and active-control were proposed respectively according to the scopes of these two kinds of exoskeletons.Additionally,an n-port network model is introduced based on the cooperation between the human and the exoskeleton,by which the system stability can be analyzed by passivity.The requirements of application and various different topologies suggest that the most suitable solution for wired networks is a hierarchical bus topology.The function allocation between the human and machine should be handled by fully considering the goal,requirements,system model,and working load.Due to the outstanding characteristic of man-machine interaction,the upper-limb exoskeleton is regarded as one of the best methods for robot tele-operation with force feedback.According to the biomechanical model of human-upper limb,optimal mechanical design was carried out by orthogonal experiment method.Due to the different structure between the exoskeleton-type master arm and robotic slave arm,a universal workspace mapping with deficient-DOF space was proposed. Some small sized pneumatic cylinders were chosen as the actuators for force feedback.The distributed hybrid fuzzy control architecture was figured out to realize the pneumatic force-feedback control,by which the tele-operation became more intuitive.In order to minimize the influence of the time-variable time delay in the process of data transmission on internet,a multi-event-based control method was utilized.The stability and unexpected factors in control process of the master exoskeleton and the slave robot arm were both monitored.Additionally,some pre-study on the curved PMA based elbow exoskeleton for force feedback control were made.The rehabilitation is an important application of the power augmentation exoskeleton.We implemented technical solution of a lower-limb exoskeleton system in light of the biomechanical model of human lower-limb.Mechanical structure was optimal designed according to the simulation results based on the 5-link model.The passive position control strategy was arranged as the simplest control method for the gait.Additionally,a 5-link model based semi-active trajectory adjusting control strategy was explored to further improve the performance of such a man-machine system.With the exoskeleton and different control strategy,physiological gait patterns and training information were obtained and restored in the database.8 healthy subjects and a paraplegic patient participated in the test experiments respectively and the results were encouraging.By the successful implementation of these two kinds of exoskeleton-type system,the basic principle of the biomechanical design and theory of the system control were verified.The work introduced in this paper has significance in the development of exoskeleton-type system in near future.