A novel decoupled XY compliant micro-positioning stage, based on a bridge-type amplification mechanism and parallelogram mechanisms, is designed in this paper. Analytical models of the bridge-type amplification mechanism and parallelogram mechanisms are developed by Castigliano’s second theorem and a Beam constrained model. The amplification ratio, input stiffness, and output stiffness of the stage are further derived, based on the proposed model. In order to verify the theoretical analysis, the finite element method (FEM) is used for simulation and modal analysis, and the simulation results indicate that the errors of the amplification ratio, input stiffness, and output stiffness of the stage between the proposed model and the FEM results are 2.34%, 3.87%, and 2.66%, respectively. Modal analysis results show that the fundamental natural frequency is 44 Hz, and the maximum error between the theoretical model and the FEM is less than 4%, which further validates the proposed modeling method. Finally, the prototype is fabricated to test the amplification ratio, cross-coupling error, and workspace. The experimental results demonstrate that the stage has a relatively large workspace, of 346.1 μm × 357.2 μm, with corresponding amplification ratios of 5.39 in the X-axis and 5.51 in the Y-axis, while the cross-coupling error is less than 1.5%.

With the development of aerospace technology, more and more scientific activities are carried out in the universe. Due to the microgravity environment of space, the control of the 6-DOF platform is different from those on the earth. First, a virtual prototype model of the 6-DOF non-contact platform was built in ADAMS. The dynamics model was developed based on the Newton–Euler method. Then, the 6-DOF backstepping sliding mode controller and disturbance observer were designed in MATLAB/Simulink. Finally, by combining the virtual prototype model in ADAMS and the control system in MATLAB, the co-simulation model was proposed. According to the simulation results, the 6-DOF backstepping sliding mode controller can well complete the positioning, 3D trajectory tracking, and vibration isolation tasks of non-contact 6-DOF platform. Quantitatively, the spatial error of backstepping sliding mode controller’s 3D trajectory tracking is only 50% of the ordinary sliding mode control and it is 20% of the nonlinear propotional-derivative-integral.

A semi-active force tracking PI controller is formulated and analyzed for a magnetorheological (MR) fluid-based damper in conjunction with a quarter-vehicle model. Two different models of the MR-damper are integrated into the closed-loop system model, which include: a model based upon the mean force-velocity behavior; and a model synthesis comprising inherent non-smooth hysteretic force and the force limiting properties of the MR damper. The vehicle models are analyzed to study the vibration attenuation performance of the MR-damper using the semi-active force tracking PI control algorithm. The simulations results are also presented to demonstrate the influence of the damper nonlinearity, specifically the hysteresis, on the suspension performance. The results show that the proposed control strategy can yield superior vibration attenuation performance of the vehicle suspension actuated by the controllable MR-damper not only in the sprung mass resonance and the ride zones, but also in the vicinity of the wheel-hop. The results further show that the presence of damper hysteresis deteriorates the suspension performance.

In order to study the vibration isolation and positioning performance of the noncontact 6‐DOF platform in the space microgravity environment, this paper presented a cosimulation model of a virtual prototype. Based on the model driven by biaxial noncontact Lorentz force actuators (NLFAs), an equivalent dynamic model has been established. In the meanwhile, the 6‐DOF sliding mode robust controller with exponential convergence disturbance observer is developed. The mechanical system simulation model was designed using ADAMS, and the corresponding 6‐DOF decoupling control system and disturbance observer programs were developed using MATLAB/Simulink. According to the mechatronics simulation results, the system can enable the floating platform to achieve micron‐level posture positioning within 0.5 s. In vibration isolation simulation, the disturbance observer can predict the external disturbance input and compensate the control force more accurately so that the floating platform can effectively suppress low‐frequency disturbance and step disturbance under the control of the sliding mode controller. And the displacement of the floating platform under the disturbance of 1–100 Hz frequency sweep is less than 1 μm.

Due to the inherent hysteresis characteristics of the smart material, the positioning accuracy of the piezo-driven manipulator was always decreased. Especially in multi-degrees-of-freedom (MDOFs) compliant manipulators driven by multismart actuators, the cross-coupled hysteresis among MDOFs decreased the positioning accuracy of such compliant platforms significantly. In this paper, the hysteresis feature identification and coupled hysteresis compensation of a piezo-driven XY manipulator was investigated. To establish the hysteresis characteristics of the piezo-driven manipulator, a modified BoucWen model has been proposed, and a Genetic Algorithm-based Particle Swarm Optimization (GA-PSO) was adopted to recognize the parameters of the model. To improve the output performances of the manipulator, the decoupling controller of the XY micromanipulator was designed, and the driven voltages were modified using the estimated coupling displacements. The experiments validated that the modified BoucWen model featured the ability to present the hysteresis process effectively, and the maximum prediction errors are 0.19μm and 0.16μm in the two directions separately. The coupled hysteresis displacement before and after implementing the decoupling controller in the X-direction was reduced from 0.56μm to 0.15μm, and the coupling effect is reduced by 73.2, while in the Y-direction, the coupling effect was also decreased by 72.9.

In recent years, piezoelectric actuators (PEAs) are widely used in precision positioning stage due to its outstanding advantages of small size, high displacement resolution and fast response. However, in practical applications, PEAs are also affected by the inherent nonlinear factors such as hysteresis and creep, which further results the positioning accuracy deceasing of the stage. In this paper, a modified Bouc-Wen model is proposed to identify the hysteresis characteristics of PEAs. In order to improve the identification accuracy of the model, the modified Bouc-Wen model parameters are identified by the Genetic Algorithm (GA) which has a good global search capability. The experimental results show that the range of the absolute error (RAE) of the modified Bouc-Wen model is reduced by 5.87% and the average fitness value (AFV) is reduced by 4.87% compared to the standard Bouc-Wen model, which further validate the accuracy of the proposed modified Bouc-Wen model.