Research On The Theory And Method For Foot And Ankle Protection Design

The design requirements of wearable devices are quite high consist in the complex shapes.The structure and shape design of protective products used for human joint protection,such as ankle protection,has attracted more and more attention.In this study,a pleasant design method of elastic elastic ankle protection pressure and semi-rigid ankle brace is proposed,which is not only based on the tissue and external shape of foot and ankle,but also based on the technologies of the surface reconstruction,the theory of clothing pressure,and the kinematics and biomechanics.The mainly works of this study are as following.(1)A multi parameter digital model of human foot and ankle was reconstructed combined with modern computer scanning technology.The method of reconstruction was based on 3D scanning data of healthy human foot and ankle and local feature invariance.The NURBS curve and surface interpolation method was then used to reconstruct the model of the foot shape.The foot and ankle bone,the muscle line and the ligament model were also constructed according to the data of CT and MRI.Finally,a multi parameter digital system model which could be used for the research of ankle injuries was reconstructed.(2)The characteristics of morphological changes were analyzed and the method of classification was proposed.Because of the changes of skin surface,the areas of ankle with different angles could be computed.The positions of the characteristics points were unified,and the correlation of characteristic dimensions was analyzed.Then the ankle grouped with the key dimensions.There were 27 groups theoretically,but only 10 groups(6 for male and 6 for female)were chosen by detecting in practice through statistical analysis and the method of clustering.(3)A spherical equiangular spiral line kinematics model and a mechanical model of foot and ankle were established.A hypothesis was proposed that subtalar joint moved along a series of spherical equiangular spiral line by the shape,position and anatomic function of talus.The kinematics model of ankle joint was constructed,and the validity of the model was verified by motion capture.Combined with the tendon distribution of the foot,a mechanical model of the foot and ankle was established,and the ankle support was analyzed taking the gait cycle as an example,and the plantar reaction force,plantar pressure,sEMG signal of foot under different extension and flexion joint angles were tested.(4)A design method of elastic ankle protection considering comfort pressure was proposed by the clothing pressure theory and the shape characteristics of ankle surface.This study analyzed the fabric material shape,elastic deformation size and corresponding curvature radius of foot and ankle.The local maximum pressure value of foot and ankle was obtained,and the position of maximum pressure and zero pressure were defined.Then the girth dimensions of elastic ankle protection were calculated according to the comfortable pressure range of human body surface.(5)A new design method of semi-rigid ankle protection products was proposed by the characteristics of foot and ankle movement and mechanics.With the kinematics law and mechanic model of foot and ankle,positive adjustment of foot and ankle movement by auxiliary force was needed.The morphological change characteristics,types matching of foot and ankle,and the range of motion were considered to the specific design of semi-rigid ankle protection.(6)The experimental test and user evaluation of the key parameters of ankle protection were conducted.According to the slice model of the foot and ankle shape,the maximum pressure data generated by the protection materials with different elastic coefficients at the corresponding positions were tested.The angle of the semi-rigid ankle protector restraining the ankle joint,the distribution of the plantar pressure and the muscle force of the external muscles were also tested by using the motion capture system,the plantar pressure meter and the sEMG signal acquisition equipment.The objective test of the key parameters above and subjective evaluation were carried out,and the effects of the design were verified.The results of this study have important theoretical and practical significance for most wearable products that need to meet the morphological changes in human movement,especially for the development and production of joint protectors.