To realize accurate attitude control, the reaction wheel is commonly used for many satellites. However, it has never used for very small satellite such as micro-class or nano-class satellites. The main reason is that existing reaction wheel is too heavy and take too much space to carry, and also needs too much electricity to work for this class of satellite. In order for such satellites to have a high precision attitude control capability, a novel attitude control device which is called three dimensional reaction wheel (3DRW) has been proposed. 3DRW consists of only one levitated spherical mass which can rotate around arbitrary axes by rotational magnetic field, while existing attitude control device consists of three or more one-axis rotating mass to realize three axes control. This leads to the reduction of the weight and volume of the system. Furthermore, the spherical mass rotates by rotational magnetic field, so there is no mechanical contact between rotor and stator. This would reduce the failure caused by the mechanical contact. For these reasons, it can be said that 3DRW has many advantages to existing reaction wheel. In this paper, we present the results of the analysis and experiment on the dynamics and control of 3DRW. First, the concept of 3DRW and analytical formulation is introduced. Then, the results of the experiment which demonstrates the dynamics and control of the system are shown. To investigate the dynamics of the rotation mass in a magnetic field without mechanical contact on the ground, we use the air levitation system and the electrical magnets which generate the rotational magnetic field around arbitrary axes. This gives the rotation mass three degree of freedom of rotation, and makes it possible to control arbitrary axes. Using this device, the characteristic of open loop control is investigated. Furthermore, the measurement system of the angular velocity of each three axes is implemented, and the closed loop control is realized. The results of the experiments are compared with numerical simulations, by which the design method and the way of estimating the electrical performance of 3DRW are obtained. Finally, we evaluate the characteristic of attitude control using 3DRW, and reveal the advantage of 3DRW for microsatellites.
展开▼
