A reluctance-type three-degree-of-freedom magnetic bearing with multi-disk has been developed to improve the high-support force density. The structure of the magnetic bearing does not use permanent magnets to simplify assembly and disassembly while enabling it to be used in special environments with high or cryogenic temperatures. The support force is expected to be reduced compared to structures with permanent magnets, but quantitative comparisons have not been made. Therefore, in this paper, a support force analysis comparison is conducted between the structure with permanent magnets and the proposed structure without permanent magnets. Moreover, design guidelines are clarified through parametric studies of design parameters to achieve the high support force density for the proposed structure. Furthermore, a new energizing method that uses magnetic flux interference is applied to the proposed structure. The analysis results show that at the maximum current, the support force is improved by 15.7% and 43.6% in the axial and radial directions, respectively, compared to the conventional method.

Various actuators have been developed to improve the performance of cooperative robots. Multi-degree-of-freedom (multi-DOF) electromagnetic actuators can rotate multi-DOF by a direct drive and can contribute to system miniaturization and higher precision. However, the biggest challenge is to increase the output because the torque cannot be amplified using a reduction gear. To solve this problem, this paper focuses on a hybrid actuation with a pneumatic actuator, which has a large output density. In this study, we propose a two-DOF pneumatic-electromagnetic hybrid actuator that integrates a bellows pneumatic actuator and a two-DOF electromagnetic actuator. First, the concept, design, and operating principle are presented. Next, the torque control method, dynamic model, and attitude control system are shown. In the torque analysis, the maximum torque of the proposed actuator is four times larger compared with a conventional two-DOF electromagnetic actuator of the same size. The dynamic simulation results show that attitude control is possible with hybrid actuation. Based on the results, a hybrid multi-DOF actuator using multiple drive sources is proposed for the first time.

A triaxial active control magnetic bearing with an axially asymmetric structure has been developed for a high-temperature turbomachinery. Since this magnetic bearing has a support force interference, disturbance suppression was not possible. A nonlinear compensator has already been proposed to solve this problem. However, the disturbance suppression performance is insufficient. Therefore, this paper proposes a switching type disturbance suppression control system that estimates a disturbance from the states and switches the controller characteristics based on an estimated disturbance. This model improves the disturbance observer performance of the already proposed a variable structure type nonlinear control system. First, the characteristics of the proposed model are presented, followed by the disturbance estimation performance of the proposed model. Next, the disturbance suppression performance of the proposed model and a conventional compensator is compared. The results verify the superiority of the proposed model over conventional compensators.

Magnetic lead screw (MLS) is a feed screw that allows non-contact power transmission. The MLSs have some advantages such as reduction of particle emission and improving positioning accuracy. However, conventional MLSs need a supporting mechanism using linear guides or slide bearings. They deteriorate the advantages of MLSs because of friction. In order to solve this problem, we propose a magnetically levitated lead screw (MLLS) for complete non-contact transmission. The proposed magnetic structure and operating principle are verified through a three-dimensional finite element method. The suspension force, thrust, and torque characteristics are investigated, and the effectiveness of the MLLS are clarified.

There is minimally invasive method called Interventional Radiology (IR) that achieves an operation by using diagnostic imaging equipment such as Computed Tomography (CT). IR has advantages that it is a minimally invasive method and it is applied widely such as lung cancer treatment, liver cancer treatment, biopsy, and so on. However, it has a problem that doctors are exposed by X-ray due to a procedure in the vicinity of the CT gantry. To solve this problem, we have developed a robot so we calling “Zerobot”. Zerobot has six DOF and controlled remotely. We previously conducted animal experiment using a rabbit to evaluate Zerobot. As a result, percutaneous puncture was impossible without epidermis cutting. Therefore, we developed a new function called instantaneously puncture that can achieve high speed and short stroke puncture like a human operator. In this paper, overview of Zerobot is described first. Then, measurement of puncture speed of a human operator is described. Furthermore, design and system structure of instantaneously puncture system is described. Finally, we present results of animal experiment using the instantaneously puncture system.