Research On Lower Limb Muscle Force Based On Human Gait Phase Classification

In recent years,the aging trend in China has become more pronounced,and many elderly people face difficulties in their daily lives due to declining or lost mobility.Additionally,there are a large number of patients with movement disorders,but only a few can receive rehabilitation training.Therefore,the demand for assistive devices for the disabled,elderly,and walking-impaired has driven the development of the lower limb rehabilitation robot industry.At the same time,analyzing muscle mechanics is crucial for the design of rehabilitation robots,but direct measurement of live muscle forces is extremely difficult.Based on these challenges,this article will analyze muscle mechanics from an engineering perspective.Firstly,based on quaternion and Kalman filter algorithms,the acceleration,angular velocity,and magnetic force data in the inertial measurement unit(IMU)are fused to calculate the attitude angle of the sensor.By attaching the IMU sensor to the lower limb of the human body and solving the data,the joint angles of the lower limb during human gait can be obtained,which is the basis for calculating muscle length and dividing the gait cycle.On this basis,a gait phase identification system is designed,and the angle data of the hip and knee joints during human gait are used to divide the gait phase.Three gait phase identification algorithms are compared,among which the support vector machine has the best accuracy and stability,and can meet the needs of phase classification and identification.Finally,the support vector machine algorithm is used to classify and identify the phases during human gait.Secondly,based on the human lower limb muscle-bone model,the human lower limb is simplified into a four-segment three-joint model,and the attachment points of the lower limb muscles on the corresponding bones are given.A reference coordinate system is established on the hip bone,and local coordinate systems are established at other joints.Using the D-H parameter method,the starting and ending point coordinates of each muscle in the reference coordinate system are obtained,and the length of the lower limb muscles is calculated using the spatial straight-line distance formula.Based on this,the muscle fiber length of the lower limb muscles is calculated,and the muscle fiber contraction speed is obtained.After obtaining all the muscle parameters,the Hill muscle force model is used to solve for the lower limb muscle force,which is compared with the muscle force analysis software Open Sim to verify the accuracy of the calculation results.Finally,the contribution of lower limb muscle force is analyzed in conjunction with the gait phase during human gait.By analyzing the force state of each muscle in different phases,the force contribution of each muscle in each phase and the specific functional role of each muscle in different phases are determined,providing a theoretical basis for the design and rehabilitation training of lower limb rehabilitation robots.