Research On Design And Experiment Of Wearable Lower Limb Myoelectric Controlled System For Stroke Patients Rehabilitation

Limb paralysis and motor dysfunction caused by stroke reduce the life quality of stroke patients.It has great social significance to study the reconstruction of lower limb motor function after stroke.Functional electrical stimulation(FES)improves the motor function of the lower limbs.The shortcomings of the existing FES systems are as follows:most of the systems are lack of intelligent control mode,some of current systems are non-portable devices and bulky,and lack of processing the artifact signal,which affects the accuracy of FES control.To stably reconstruct the motor function of paralyzed limbs,our research group proposed the concept of"Electromyographic Bridge(EMGB).The principle of EMGB is as follows:the myoelectric signal is taken from the body surface of healthy limbs or the healthy limbs of hemiplegic patients as the control signal.By encoding the key information such as strength and time sequence,the electrical stimulation pulse sequence that reflects the muscle activation state is generated,and then act on the paralyzed limb.Based on the previous work of our research group,this thesis focuses on solving the problem of removing artifacts and developing wearable devices,and therefore to form the rehabilitation system to reconstruct the lower limb motor function.The main researching content of this thesis is as follows:1.Overall scheme design of lower limb myoelectric controlled rehabilitation system:according to the three core problems of the system,the design scheme and design requirements of the system are proposed.The whole system is divided into two parts,includes a EMG detection band and a FES band.The EMG detection band realizes EMG detection,signal processing and transmission of the stimulation parameters.The FES band has the capability to receive,regenerate and release the electronic signal,and applied on the paralyzed limb to complete the functional reconstruction of the paralyzed limb.2.Research on sEMG detection,signal processing and signal transmission of EMG detection band:the EMG detection band is divided into three parts:anti-artifact signal detection circuit,signal processing circuit and signal transmission circuit.The switch timing of the input selection circuit and negative feedback circuit are used to adjust the pass band of the filter circuit,the EMG detection of the paralyzed limb in the stimulation state is realized and the stimulation artifacts are suppressed.The signal processing circuit is used to filter the residual M-wave within the detected signal,and the stimulation parameters are generated in real time through the MAV/NSS dual-coding based on the time domain characteristics.The signal transmitting circuit uses the low-power bluetooth module to load the stimulation parameters into the wireless signal.A 3D printing shell is designed for the EMG detection band circuit,therefore,the detecting electrode can be attached quickly to provide a convenient rehabilitation training to patients.3.Research on signal receiving,signal regeneration and signal release.The hardware part of the FES band uses the controlled signal of the regeneration circuit to trigger the input signal,and release the constant current electrical stimulation through the voltage controlled current source.Through the H bridge,the controlled signal is converted into a current biphasic charge balance pulse signal,and the signal is released from the paralyzed limb by stimulating the hydrogel electrode.A stimulation isolation circuit is introduced in front of the core stimulation circuit to provide high-frequency transient immunity for the isolation layer and maintains the stability of the core stimulation circuit.The embedded program design part includes signal regeneration of stimulation-controlled signal and control of the switch.A 3D printing shell for the FES band circuit provides comfortable wearing,convenient use and stable output,with the function of preventing muscle fatigue.4.Construction and human experimental research of myoelectric controlled rehabilitation system:the EMG detection band and FES band were assembled and tested,and the human experimental research of system was carried out.Human experimental research is divided into the practice research of healthy people,and the experimental research of patients with lower limb hemiplegia.The experimental results show that the system realizes the acquisition of the sEMG signal in the healthy limb and the signal releases in the paralyzed limb under the stimulation state.It helps the subjects to complete the rehabilitation training,which is in line with the design requirements of the system for real-time signal detection,real-time signal processing,wearable design and system stability.