Research And Implementation Of Outdoor-oriented Low-cost IMU Gait Information Acquisition System

Gait analysis is a method to assess the walking ability and characteristics of human body by obtaining gait parameter information of human walking by scientific means.It is of great significance in the fields of rehabilitation medicine and robot development.IMU can extract the acceleration and angular velocity information of the object,and obtain the attitude,velocity and position of the object by combining the inertial navigation algorithm.Through the analysis of the gait characteristics and the basic principles of IMU,this paper studied the key technologies and implementation methods of the outdoor lowcost IMU gait information acquisition system.The main research work is as follows:In view of the present gait and the high cost of information collection system,in the case of can't be outside of the laboratory data acquisition,this paper can be used in outdoor is developed low cost IMU gait information acquisition system,the system through the multiple locations of lower limbs in human body of IMU angular velocity information collection corresponding to the location of the acceleration sensor nodes,by using CAN bus to realize information collection,data between various nodes finally packaging upload first place machine for further human gait parameters are calculated.Firstly,this paper completes the hardware design of IMU node,including microcontroller minimum system,sensor peripheral circuit,communication and interaction circuit,etc.Secondly,the software design of the data node is completed,which is mainly the initialization of the controller,data acquisition of the sensor,filtering,attitude solution and communication and interaction tasks.Meanwhile,the embedded real-time operating system FreeRTOS is introduced to realize the effective scheduling between tasks and the safe transmission of data.Finally,aiming at the accuracy of low-cost IMU sensor data,the modeling and error analysis are carried out,and the calibration of IMU sensor data is completed through the calibration process.Aiming at the problem that the original information of IMU sensor is difficult to be used directly in gait analysis and the data reference value is limited,this paper studies and realizes the calculation methods of joint Angle,gait phase and spatial parameters.Firstly,through the analysis of human joint motion characteristics and sensor principle,the angular velocity integral joint Angle calculation method based on sensor orientation and hinge model is realized,and the advantages and disadvantages of the two methods are compared.Secondly,through the comparative analysis of the human gait cycle and the foot sensor information,a method of gait phase division using multi-sensor information as the criterion is realized,and a misjudgment correction method is introduced to improve the accuracy of gait phase determination.Finally,through the combination of inertial navigation principle and human gait characteristics,the calculation method of human spatial parameters based on zero speed correction is realized.The experiment verified that the error of joint Angle was ±7°,the maximum error of gait phase was ±50ms,and the maximum error of step length and displacement were ±8cm and ±15cm,respectively.Combined with the characteristics of human gait and the basic principle of IMU,this paper studied and realized the outdoor available low-cost IMU gait information acquisition system,including data acquisition,data transmission hardware and software design and gait algorithm module,and finally verified the effective use of parameters through experiments.