Research On Hierarchical Control Of Flexible Ankle Rehabilitation Robot Oriented To Assist-as-needed

With the development of science and technology,rehabilitation robots have been more and more used in the field of rehabilitation therapy.With the traditional control method,the robots can lead the whole rehabilitation training,which can effectively improve the motor ability of patients with limb injury and reduce the workload of rehabilitation trainers.So they have been widely used in the early stage of rehabilitation training.In the middle and late rehabilitation training stages,patients have certain active motor ability and even can lead the rehabilitation training.But traditional passive rehabilitation training often neglects this ability.Therefore,it has become a hotspot in the field of rehabilitation robot research to establish an active control strategy which has strong adaptive ability,good flexibility and can fully stimulate the active motion patients' ability.The pneumatic muscle has many advantages,just like high flexibility,low cost and good safety,which can fully guarantee the flexibility and safety in the rehabilitation training.Rehabilitation robot based on this driver has been widely used in the active control strategy research.Ankle rehabilitation robot driven by three pneumatic muscles is taken as the research object in this paper,which combines the force/torque signal of humancomputer interaction to study the adaptive admittance control.At the same time,according to the contractile force characteristics of pneumatic muscles,a joint flexibility driver is designed to achieve the flexibility control of pneumatic muscles.Combe the above two control methods to adjust the control mode freely based on patient's active ability.The main contents are as follows:(1)Aiming at the problem that position control can not modify desired trajectory according to human-computer interaction,design an admittance control based on position control to realize trajectory reconstruction.Meanwhile lead into a new adaptive algorithm.According to the human-computer interaction information,adjust the parameters of admittance model,just like the stiffness.And then a new desired trajectory is obtained.That means the patient's ankle motion space is also adjusted,so as to increase the flexibility of the robot and stimulate the patient's active motion ability.(2)Aiming at the problem of poor flexibility in passive rehabilitation training,design a joint flexibility controller to adjust the stiffness based on flexibility characteristics of pneumatic muscles.On this basis,get the passive torque of ankle motion by particle swarm optimization(PSO).Combining the adaptive admittance control,propose a hierarchical compliance control strategy.Design a complete set of active rehabilitation training method to ensure the safety and then adjust the auxiliary output according to the patient's need.(3)In order to fully meet the specific patient's need in rehabilitation training,design a set of rehabilitation training control system based on assist-as-needed control method.The patients can choose the training mode freely according to the location and force/torque information.Making the different choice in the different rehabilitation stage,patients can lead the rehabilitation training with a more free mode.At the same time,design a human-computer interactive game to increase the challenge in the rehabilitation training.The patients in the late rehabilitation stage will participate in the training more actively.