Comfort optimization of a new type of foot mechanism for lower extremity exoskeleton / 生物医学工程学杂志

In order to reduce the impact caused by the contact between the foot and the ground when wearing the lower extremity exoskeleton under the condition of high load, this paper proposed an exoskeleton foot mechanism for improving the foot comfort, and optimized the key index of its influence on the comfort. Firstly, the physical model of foot mechanism was established based on the characteristics of foot stress in gait period, and then the mathematical model of vibration was abstracted. The correctness of the model was verified by the finite element analysis software ANSYS. Then, this paper analyzed the influence of vibration parameters on absolute transmissibility based on vibration mathematical model, and optimized vibration parameters with MATLAB genetic algorithm toolbox. Finally, this paper took white noise to simulate the road elevation as the vibration input, and used the visual simulation tool Simulink in MATLAB and the vibration equation to construct the acceleration simulation model, and then calculated the vibration weighted root mean square acceleration value of the foot. The results of this study show that this foot comfort mechanism can meet the comfort indexes of vibration absorption and plantar pressure, and this paper provides a relatively complete method for the design of exoskeleton foot mechanism, which has reference significance for the design of other exoskeleton foot and ankle joint rehabilitation mechanism.

Modeling and dynamic analysis of stretcher bed on ambulance based on virtual prototyping technology / 医疗卫生装备

Objective To obtain the dynamic characteristics of the stretcher bed without absorber, and to optimize the absorber. Methods Pro/E and ADAMS were used to build the dynamic model of the stretcher bed on ambulance. The principle of random sine wave superposition and Visual Basic language were used to produce time-domain pavement roughness which could stimulate the model. The system was analyzed. Results The curve of vertical acceleration in time and frequency domain and the RMS of vertical acceleration without absorber were obtained by simulation., and a reasonably suited pair of stiffness and damping coefficient was found to reduce the vibration intensity. Conclusion The inherent frequency of the stretcher bed is 2.7Hz, which is out of the sympathetic vibration area of decubital body. Through adjusting and optimizing the stiffness and damping of vibration reduction equipment, the stretcher bed is more comfortable.