This study presents an observer-based adaptive fuzzy dynamic surface force control strategy for pneumatic polishing system with uncertain contact environment model and full-state constraints. First, a fuzzy logic system is employed to approximate the uncertain nonlinear dynamics of the pneumatic polishing system end-effector, and a fuzzy state observer is designed to estimate the unmeasured states. Further, to enhance the controller’s response speed, a variable separation method employing fuzzy basis functions and the dynamic surface control technique are adopted to address algebraic loop issues and prevent computational complexity explosion. A logarithmic-type barrier Lyapunov function is embedded into each step of the controller design to ensure that all system states satisfy the predefined constraints. Finally, an adaptive fuzzy dynamic surface force controller with full-state constraints is developed to ensure fast and accurate control of the polishing force in an uncertain contact environment while maintaining all states within predefined constraints. The effectiveness and applicability of the proposed control algorithm are experimentally verified using a pneumatic polishing system.

The pneumatic vibration isolator (PVI) plays an increasingly important role in precision manufacturing. In this paper, aiming to detect the performance of the pressure regulator in the PVI system, a PVI testing system with a pressure regulator is designed and developed. Firstly, the structure of the pneumatic spring is presented and analyzed, and the nonlinear stiffness is obtained based on the ideal gas model and material mechanics. Then, according to the working principle and continuity equations of ideal airflow, a dynamic model of the PVI system with a pressure regulator is established. Through the simulation analysis, the vibration isolation performance is improved with the efficient and precise pressure regulator. The average values of both the vibration velocity and transmission rate decrease when the vibration is set to 4, 10, 20 and 40 Hz, respectively. The experiments demonstrate the reliability and effectiveness of the pressure regulator. This achievement will become an important basis for future research concerning precision manufacturing.

High trafficability and stability are the most two significant features of the forestry chassis. In this study, in order to improve surface trafficability, a novel articulated wheel-legged forestry chassis (AWLFC) is presented. To balance the trafficability and stability, a serial suspension system which is a combination with the active four-bar linkage articulated suspension (AFLAS) and passive V shape rocker-bogie is proposed. Then, parameter optimization with a comprehensive object function is implemented not only to enhance the trafficability and stability benefit of the structure but also to reduce the wheel slip. After that, through the flexible kinematic model based on screw theory, characteristics such as leveling ability and surface profile accessibility of the chassis are analyzed. The minimum accessible radius is obtained as 3088 mm, and the longitudinal and lateral leveling angle reaches to 22 deg and 28.7 deg separately. The new chassis performs better on leveling ability and surface profile accessibility than the forestry chassis in the current literature. Finally, through the results of simulation and prototype experiment, error rates related to the flexible analysis are reduced by 12.2% and 8.6% compared with the rigid model. Previously inaccessible forestry working environments can be available with the development of AWLFC.

Since the constraints of the rod position and velocity of pneumatic servo system (PSS) should be considered in real applications, a finite-time adaptive fuzzy tracking control based on state observer is studied for a PSS subject to input voltage saturation and full-state constraints. First, a state observer is constructed by the fuzzy logic system (FLS) to estimate the unmeasurable rod velocity through the displacement sensor signal. Then, by the utilization of the backstepping scheme and FLS, the output-feedback stabilization controller is constructed to ensure the control performance of the PSS, in which the barrier Lyapunov functions are employed to handle the constraints of the rod position and velocity. Furthermore, it is proved that the finite-time convergence of the rod position tracking error is guaranteed, all the signals in the closed-loop PSS are bounded, and rod position and velocity are not transgressed their constrained sets. Finally, the experimental results show that the proposed algorithm improves the control precision and response speed.