Parametric investigation to optimize the dynamic range of mr damper for vibration control

Abstract

This research sought to identify the solution of shock absorption for vibration control (in this case, to reduce the effect of the heel strike of the transtibial amputee in walking). This research proposes a device which is a damper-based shock absorber installing on a prosthetic limb that will be used by the transtibial amputee. The prosthetic leg adopts a semi-active damper to capture the advantages of passive damper along with to perform as good as an active damper. Magnetorheological (MR) damper, which utilizes the benefits of MR fluids, is one of the most promising semi-active devices in mitigating the vibration. MR fluids is a smart material because of the ability to control the rheological properties by tuning the external magnetic field strength. Moreover, mechanical simplicity, fast response, and low power consumption have attracted more interest on this damper. However, the challenging aspect of utilizing this device is to understand their performance under varied input parameters. Understanding the behavior of the MR damper is the critical feature to use this damper fully. A well-known mathematical model, the Phenomenological (Modified Bouc-Wen) model, is used to model the MR damper behavior. To use this model, a relationship between the damper parameters, including force, displacement, velocity, current, and frequency, should be available. An experimental study of MR damper is done by the researcher to acquire those relationships. A comprehensive optimization methodology to estimate the parameters of the Modified Bouc-Wen model is necessary. The researcher compares two optimization algorithm, which is Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) to estimate the parameters. From the comparison, PSO, inspired by the behavior of bees swarming for the optimization methods, has higher accuracy, which is 95.92% compared to GA, which is 94.71%. The precision of the optimization of the Modified Bouc-Wen parameters is from 92.3% to 96.5%. Each parameter fits the function of input current and frequency using the polynomial equation (maximum 3rd polynomial order). The precision of the fitting is from 87% to 98.4%. Robust Controller is developed to control the MR damper for transtibial prosthetic limbs. In this research, prosthetic limb applications adapt H∞ robust controller and inverse MR damper model. The result of the controller design compared to the targeted behavior is up to 92.51% accuracy. The simulation's performance is presumed to be acceptable since it almost followed the pattern of the targeted design.