Proceedings of the Institution of Mechanical Engineers,Part I: Journal of Systems and Control Engineering

Magnetic levitation technology, for magnetic bearings and magnetically suspended motors, is a cutting edge technology to produce artificial hearts and higher performance blood pumps. A wider blood gap and the elimination of the contacting parts in the device based on the maglev technology provide better blood compatibility and higher durability of the device. Several maglev pumps developed at Ibaraki University are introduced in this article. Maglev pumps have been designed for different medical requirements and for different magnetic suspension systems. All pumps have sufficient suspension and pump performance as blood pumps. The axial suspension system with a double biased hybrid magnetic bearing is explained in detail as one example of maglev blood pumps.

This article focuses on the operational behaviours of two novel bearingless reluctance slice motor prototypes. After a brief introduction of the two systems, we present our experience with both bearingless drives. On this basis, commonalities and differences in terms of construction, geometric constraints, winding systems, force-to-torque ratio, power electronic utilization and efficiency are outlined in order to demonstrate the suitability of the reluctance slice motor concepts for industrial applications.

The dynamic system simulation and the control design process of the new developed bearingless rotating-field axial-force/torque motor (AFTM) requires an augmented state-space framework for mathematical system description. After a short summary of this framework, the main focus of this paper concentrates on the model parameterization using state-of-the-art drive gauging procedures. A direct comparison features minor deviations between magnetostatic finite element analysis simulation results and available measurement data. Moreover, a closed-loop control concept for concurrent axial position stabilization and vector drive control of AFTMs is proposed. The quality of the closed-loop control system simulation is reviewed using relevant measurements of the functional prototype. A presentation of the disassembled prototype and a summary of its performance data concludes this paper.

This article presents an eddy current damper of a passive reaction force compensation mechanism for a linear motor motion stage. The reaction force compensation mechanism with a movable magnet track and eddy current damper resolves problems with the existing spring-based reaction force compensation mechanism such as resonance, design freedom, and difficulty of assembly and manufacturing. A simplified mathematical model of the eddy current damper is derived considering the sinusoidal magnetic flux density distribution and effective width of the eddy current damper, which shows important design factors of the eddy current damper–based reaction force compensation mechanism. Then, force of the eddy current damper according to the constant speed motion of the magnet track is investigated using multi-physical finite element analysis and is verified by experiments. Finally, the passive reaction force compensation with movable magnet track and eddy current damper is identified by experiments, and the finite element analysis of the eddy current damper is verified with free and forced vibration responses.

This article presents a discrete sliding mode variable structure control used for the speed governing system of marine diesel engines. It is widely accepted that the steady operation of marine diesel engines plays an important role in ensuring the power quality of marine electronic system and good engine performance. In other words, it means that a speed governor with excellent performance is crucial to ensuring the steady rotating speed of a diesel engine. However, due to the fact that diesel engine normally has a complex structure and is often influenced by multiple and nonlinear factors, a traditional proportional integral differential controller cannot optimize the sailing parameters of ships, making it difficult to satisfy the requirements of the speed control for diesel engines under various operation conditions. In view of this problem, this article developed a nonlinear mathematical model of the speed governing system for diesel engines based on experimental tests. Moreover, a discrete sliding mode controller was designed by applying the discrete sliding mode variable structure control, and a simulation model was then developed under the Simulink environment, illustrating that the performance of the designed sliding mode controller is much better than a traditional proportional integral differential controller. Finally, a bench test used for the nonlinear speed governing system based on the discrete sliding mode variable structure control approach was carried out using the bench of a diesel engine Model 2135. The experimental results further illustrated that the discrete sliding mode variable structure controller showed some super advantages, such as smaller overshoot and error, faster response and stronger anti-jamming capability, when comparing with the traditional proportional integral differential controller.

Continuum robot modeling is a research topic that focuses on ways to develop kinematic models while respecting some kinematics specificity as well as mechanical properties of such class of robots. The purpose of this article is to present a new alternative approach for solving inverse kinematic models for multi-sections of continuum manipulators. To achieve this work, it is assumed that each constitutive section is curved in a circular arc shape with an inextensible central structure axis. At first, the article presents a solution of an inverse kinematic model for one bending section and details some adopted methodologies, based on the identical inverse kinematic model of parallel robots, used for computation of the links’ length. The latter allows concatenating between multiple platforms to realize a bending section. The inverse kinematic model of the multi-section manipulator is then developed using a modular concept where the endpoint coordinates of each bending section are determined using a metaheuristic method. Finally, to validate the proposed approach, some simulation and experimental studies have been carried out on the Compact Bionic Handling Arm. From this investigation, it was found that the multiple test results show the ability of the developed metaheuristic approach to avoid obstacles and to adopt a real-time implementation with multi-section configuration. On the other hand, this type of concept can enable to model all continuum robots with multiple bending sections.

Hydraulic axial piston motor is one of the fundamental components in hydraulic systems; it is widely used in engineered machine, especially in high-power drive or reciprocating motion, such as hydraulic excavator. For hydraulic axial piston motor efficient planning, in addition designing and controlling are required for system operating safety and efficiency. Simulation delivers an advantage over analytical approaches and allows better understanding of the motor performance. For multi-piston hydraulic motor, one of the simulation methods, distributed parameter model, could analyze the detailed performance in each piston chamber. Therefore, in this study, we investigate the characteristics of hydraulic axial piston motor by setting up a distributed parameter model based on physical prototype, which includes mechanical–hydraulics coupling process. The effects of the dynamic pressure inside the piston chamber, the fluidic compressibility and other related parameters are considered in the coupling process. At the same time, the distributed parameter model of hydraulic axial piston motor was used in the simulation model of hydraulic excavator. The results indicate that in two-way hydraulic axial piston motor, the valve plane should adopt symmetrical structure, and silencing groove set should be put on both ends of the valve plane slots, which could reduce pressure ripple and overshoot in the piston chamber. Furthermore, the torque characteristics are highly affected by the clearance between the piston and the cylinder bore. Through this research, we may have a better understanding about the mechanism of output torque fluctuation in hydraulic axial piston motor, and the pressure ripple and overshoot in the piston chamber due to through-flow area discontinuity between the silencing groove and the ends of the valve plane slots. The model is verified using a nine-piston hydraulic motor in hydraulic excavator.

Charge control for a piezoelectric actuator is supposedly unaffected by the hysteresis effect; however, the voltage applied to the actuator covers both the effective force-generating voltage and the hysteresis voltage. In this article, this hysteresis nonlinearity is considered an extra disturbance over a linear system. A novel approach entailing the use of the parasitic capacitance charge feedback in conjunction with a Preisach model to estimate the hysteresis disturbance is proposed. The estimated extra voltage enables the controller to augment its effort with an additional term to compensate for this loss. The article also describes the establishment of an adequate Preisach model. The proposed approach applies a low-pass filter and feedforward compensator to improve the tracking performance. Control results under sinusoidal reference and staircase reference tracking confirmed the effectiveness of the proposed compensation in eliminating the hysteresis effect and achieving high-precision control.