Research On Wearable Soft Sensing Measurment System For Sagittal Motion Of Lower

The lower extremity joints move mainly in sagittal plane and the wearable lower limb sagittal motion measurement system has broad prospects in the fields of medical rehabilitation,film,television animation,sports and fitness.The mainstream lower limb motion measurement system has problems with motion space and comfort.The silicone rubber soft sensor is a capacitive flexible strain sensor,which has the advantages of comfort,lightweight and low cost.Therefore,this paper explore the wearable soft sensing measurement technology of motion of lower extremities in sagittal plane based on the silicone rubber soft sensor.The specific contents are as follows.Firstly,the overall design of the wearable measurement system is carried out.according to the motion measurement requirements of the lower extremities in sagittal plane and the characteristics of the silicone rubber soft sensor.Specifically,it contains analyzing the joint movement pattern of the lower limbs,establishing the motion model of the lower limb joints and demonstrating the feasibility of the soft sensor for joint motion measurement.To complete the integration of the system,the placement position of the soft sensor is determined based on the highest sensitivit y principle and the reliable integration carrier is selected and the soft sensor integration process is designed.The influence of the integrated carrier 's and the soft sensors' degrees of freedom is analyzed,which guides the design of positioning marker points.According to the requirements of the optimization of electrical parameters,the soft sensor system theoretical detection model and the communication protocol is analyzed and verified.In order to meet the requirements of signal acquisition time and dynamic response time,a new filtering algorithm is designed and parameters are optimized through experiments.The silicone rubber soft sensor is the core component of the measurement system.In order to improve the system performance,this paper deeply studies the soft sensor noise shielding and preparation process.The principle of noise source in the working environment affecting the soft sensor output signal is based on the parasitic capacitance and the action is based on the principle of electrical shielding,which is the soft sensor shielding structure and using the shielded line,verifying the effectiveness of the electrical shielding through experiments.The flexible electrode materials and packaging processes is optimized to meet the requirements of flexibility and integration for lower limb motion measurement systems.After analyzing the soft sensor process defects,the preparation process and stripping process of flexible electrode are optimized.The performance index of soft sensor is tested in dynamic.The calibration is the key link of the measurement system.Therefore,this paper studies the calibration technology of the measurement system for engineering applications.Initially,the calibration is based on the image and Open CV image processing algorithm to achieve the lower limb joint sagittal plane motion angle measurement.What's more,the calibration system's hardware and software are completed,to achieve limb motion measurement system's calibration.Finally,on the basis of the above work,this paper carry out an experimental study of the lower limb motion measurement system,and test s the performance of the system performed error of the hip,knee and ankle joints' angle in the sagittal plane.Compared with the commercial Phase Space dynamic capture system,the standard deviation is within 5° under gait and lifting motion,meeting the requirements of most occasions in exoskeleton assist and human-computer interaction.So the feasibility of this lower limb motion soft sensing measurement system technology is demonstrated.