Prosthetic Knee Based On A Magnetorheological Damper With The Double Ended Structure And The Control Methods For The Constituted Magnetorheological Damper Based Lower Limb Prosthesis

The lower limb prosthesis with the prosthetic knees can not only restore the damaged motion ability of the amputee,but also can partly heal the mental wounds because of their structures which are similar with the lower limbs.So that the lower limb prostheses are the important assist devices for the amputee.As the significant parts of the lower limb prostheses,the prosthetic knees can imitate the swing of the human knee joints.Amount the prosthetic knees integrated into the lower limb prosthesis,the magnetorheological damper based prosthetic knees(MRPKs),which control the postures of the lower limb prostheses by adjusting the reversible and controllable yield stress of the magnetorheological(MR)fluid,have the rapid response and lower energy consumption,so they have been concerned by more and more researchers.Although the MRPKs have great progressions,they still have some drawbacks: 1)Most of the presented MRPKs apply the MRDs(MRDs),whose MR fluid works in the flow mode and uncontrollable damping forces are high.2)These research works of the MRPK have not considered the effects of the hysteresis of the MRD on the swing angle of the MRPKs.3)The motion controls of MRPKs mainly uses the trajectory tracking control methods to control the swing angles of the knee joints,so that the swing angles of the knee joints of the MRPKs can follow the fixed reference angle curves.In this way,the reference angle curves can not be adjusted on-line,and the adaptability to surrounding changes is not strong,which limits the further application of MRPKs.To solve the above mentioned problems,a single axis MRPK is proposed and developed based on the MRD which has the double-ended structure in this paper.Based on the proposed MRPK,the MR based lower limb prosthesis(MRLLP)is developed and modeled,and the co-simulation model of the MRLLP is established in the ADAMS and the Simulink.Using the established co-simulation model,the effects of the hysteresis of the MRD on the swing angle of the shank of the MRLLP are analyzed.On this base,to suppress the effects of the hysteresis,a trajectory tracking control method is proposed and realized based on the slide mode control.Based on the invariant set theory,the Cardioid oscillator with the asymmetrical time ratios is proposed,and the Cardioid oscillator based central pattern generator(COCPG)model is proposed to imitate the swing of the lower limb when a healthy man walks.By applying the COCPG model,the model reference control method for the MRLLP are proposed and realized.The research works and the innovations in this dissertation can be summarized as follows:1.A single axis MRPK is proposed and developed based on the MRD which has the double-ended structure in this paper.By using the proposed MRPK,the MRLLP which includes the prototype of the proposed MRPK,prosthetic shank,prosthetic foot,and angle sensor has been developed.On these bases,the MRLLP has been dynamical modeled,and its virtual prototype has been established in the ADAMS.By using the established virtual prototype of the MRLLP,the desired damping force of the MRD when the MRLLP walks in the frequency of 1 Hz has been analyzed.Additionally,the manufactured MRD has been experimental tested.2.The sliding mode tracking control(SMTC)method for the MRLLP is proposed to suppress the effects of the hysteresis on the swing angle of the shank according to the robustness of the sliding mode control to the uncertain disturbance.In the ADAMS and the Simulink,the co-simulation model of the MRLLP is established and applied to analyze the effects of the hysteresis of the MRD on the swing angle of the shank of the MRLLP.On this base,the SMTC method for the MRLLP is proposed to suppress the effects of the hysteresis of the MRD according to the robustness of the sliding mode control to the uncertain disturbance.By using the established co-simulation model,the performances of the SMTC method on the suppressing the effects of the hysteresis and the robustness to the disturbance are analyzed.3.A Cardioid oscillator for imitating the periodical progresses with the asymmetric time ratios and a Cardioid oscillator based CPG(COCPG)model of the human lower limb for imitating the swing angles of a walking lower limb are proposed.By using the numerical simulation,the asymmetry,convergence,anti-interference,and phase locking of the Cardioid oscillator are analyzed.Furthermore,the frequency,amplitude,and offset of the COCPG model are discussed.To verify the accuracy of the COCPG model,the outputs of the COCPG model are experimental compared with the measured motion trajectories of the lower limb.4.A COCPG based model reference control(COCPGMRC)method for the MRLLP is proposed to control the MRLLP to more naturally imitate the swing of the human shank and improve the adaptability of the MRLLP to the surrounding changes.By applying the COCPG model as the reference model to imitate the swing of the human shank,the COCPGMRC method can control the MRLLP to more naturally imitate the swing of the human shank and improve the adaptability of the MRLLP to the surrounding changes.On these bases,by using the co-simulation model of the MRLLP,the accuracy of the COCPGMRC method on the shank swing control of the MRLLP and the performance of the COCPGMRC method on depressing the disturbance are analyzed.5.The rapid control prototype of the MRLLP is established based on the real-time simulation system(type: dSPACE DS1103).Furthermore,a leg simulator-based test system for the lower limb prosthesis(LSTSLLP)and a walking test system for the lower-limb prosthesis(WTSLLP)are established.By using the established LSTSLLP and the WTSLLP,the rapid control prototype of the MRLLP is experimental tested via the SMTC and COCPGMRC methods,and the experimental results have been compared with the rapid control prototype via the CT+PD and ON/OFF control method.