Yo Sakaidani

Analysis of 2-Degree of Freedom Outer Rotor Spherical Actuator Employing 3-D Finite Element Method

To drive a conventional motor drive system, the number of degrees of freedom needed has to be equal to the number of actuators employed, and this causes the system to be larger and heavier. To solve these problems, the development of a spherical actuator which can rotate around multi axes is being conducted. In this paper, we propose a new spherical actuator with an outer rotor to produce higher torque density and describe the control method for open loop drive. Static torque and dynamic characteristics of the actuator are clarified by employing 3-D finite element method and are verified from experimental results of a prototype.

Experimental Verification of Feedback Control of a 2-DOF Spherical Actuator

To drive conventional motor drive systems that have multiple degrees of freedom (DOF), such as industrial robot arms, the number of actuators employed has to be equal to the number of DOF. This causes the system to be large and heavy, and also have a lower overall efficiency. To solve these problems, the development of spherical actuators, which can rotate around multiple axes, is being conducted. In general, multi-DOF actuators have many poles and coils, and the currents of the coils have to be controlled individually, making the control system complicated. In this paper, we propose a feedback control method for a 2-DOF actuator that enables the currents of the coils to be easily determined. The effectiveness of the control method is verified through experimental verification.

Feedback Control of the 2-DOF Actuator Specialized for 2-Axes Rotation

Recently many multi-degree-of-freedom actuators have been proposed and we ourselves have proposed a 2-degree-of-freedom spherical actuator. In this paper a feedback control method is proposed, and the dynamic operating characteristics under feedback control are computed using 3-D finite element method analysis. In addition, in order to verify the simulation results, experiments using a prototype are carried out.

Characteristics Analysis of a 2-D Differentially Coupled Magnetic Actuator

In multi-degree-of-freedom (multi-DOF) systems, a number of motors are used to achieve a multi-DOF motion. However, these systems have problems, such as heavy weight, large size, and no back drivability due to the large number of motors. In order to solve these problems, there has been much work on multi-DOF motion using one actuator. In this paper, a novel 2-DOF differentially coupled magnetic actuator is proposed, and its structure and operating principle are described. A 2-D motion can be realized with the conventional motor control circuits.

Experimental Evaluation of the Static Characteristics of Multi-Degree-of-Freedom Spherical Actuators

Multi-degree-of-freedom (multi-DOF) actuators have been developed for the fields of robotics and industrial machinery.

Comparison of a 2-DoF differentially coupled actuator with and without auxiliary yokes

Multi-degree-of-freedom systems are used in industrial robots and humanoid robots. These systems are composed of a lot of motors, gears, and links, and these make the systems complicated. In order to make the systems simple, there have been many researches that can produce multi-degree-of-freedom motions using 1 actuator. In this paper two types of 2-DoF actuators are proposed. The operating principles are based on a differential gear in vehicles and they can be controlled utilizing a conventional driving circuit. The torque characteristics of the actuators are computed using 3-D finite element analysis. Finally, the 2 actuators are compared.

A 2-D differentially coupled magnetic actuator

A novel magnetic actuator which uses a differential drive mechanism is proposed in this study. The basic structure and operating principle is shown and static torque analyses are conducted employing 3-D FEM. It is shown that the actuator can achieve a 2-DOF motion with simple control equipment and control method. Dynamic torque characteristics are analyzed. It is found that force and torque could be generated by controlling the current phases.