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Spacecraft Actuators
Published in Yaguang Yang, Spacecraft Modeling, Attitude Determination, and Control Quaternion-based Approach, 2019
Reaction wheel and momentum wheel are very similar. They both have flywheel(s) and are driven by electric motors. Both of these are used for attitude control. A reaction wheel is spun up and down to create the torque to either compensate disturbance torque to stabilize the spacecraft or to create a torque and force the spacecraft to rotate for attitude manipulation. A momentum wheel is always spinning at a very high speed, which creates a momentum bias, making it resistant to changing its attitude. But a momentum wheel can also be used as a reaction wheel, meaning that the acceleration and deceleration is near a momentum biased high speed instead of near the zero speed. The torques of both reaction wheel and the momentum wheel are generated from acceleration or deceleration of the rotational flywheel and torque can be calculated by the following relation [109] () u=−h˙w=−Jwω˙
Aerospace Controls
Published in William S. Levine, Control System Applications, 2018
M. Pachter, C. H. Houpis, Vincent T. Coppola, N. Harris McClamroch, S. M. Joshi, A. G. Kelkar, David Haessig
Another important class of actuators used for attitude control are reaction wheel devices. Typically, balanced reaction wheels are mounted on the spacecraft so that their rotational axes are rigidly attached to the spacecraft. As a reaction wheel is spun up by an electric motor rigidly attached to the spacecraft, there is a reaction moment on the spacecraft. These three reaction moments provide the control moments on the spacecraft. In some cases, the effects of the electric motor dynamics are significant; these dynamics are ignored in this chapter.
Hybrid robust fault detection and isolation of satellite reaction wheel actuators
Published in Journal of Control and Decision, 2022
H. Abbasi Nozari, Paolo Castaldi, S. J. Sadati Rostami, Silvio Simani
Stimulated by an increasing advancement of space mission requirements, availability and reliability have become important in designing the satellite Attitude Control System (ACS) whose components are vulnerable to faults. In this context, the Fault Detection and Isolation (FDI) systems deliver fundamental information about the satellite's health status which allows subsequent accommodation actions to improve its availability and ensure mission success. Generally speaking, an FDI system is used to detect and isolate faults, i.e. to determine whether or not a fault has occurred and the affected device (sensors, actuators, components) (Wie, 1998). The satellite dynamics are highly nonlinear and include the Reaction Wheel (RW) dynamics with complex saturation and friction characteristics, space environmental disturbance torques such as gravity-gradient torque, aerodynamics torque, Earth magnetic torque, and the inertia uncertainty (Meng, Zhang, Li, et al., 2013). These factors may adversely affect the safety and reliability of the satellite ACS and even provoke the satellite mission abortion. Consequently, the development of an FDI system robustified against unknown disturbances and uncertainties is essential for controller reconfiguration, maintenance, repair, or other operations.
Balancing control of a bicycle-riding humanoid robot with center of gravity estimation
Published in Advanced Robotics, 2018
Chun-Feng Huang, Yen-Chun Tung, Hao-Tien Lu, T.-J. Yeh
As far as control studies for bicycles are concerned, advances in digital computers, sensor and actuator technologies have raised research interests in developing self-balancing robot bicycles. A self-balancing bicycle uses inertia sensors to detect the posture (mainly the roll angle) of the bicycle and actuators to bring it to balance. There exist several mechatronic solutions to construct a self-balancing bicycle. For example, in [7], using the steering angle as the input, a PD control is designed to stabilize the roll motion of the bicycle. Similar PD type control was also used in [8] except that the movement of an inverted pendulum which simulates the COG motion of the rider is treated as an extra control input. A gyroscopic stabilization unit, which consists of two coupled gyroscopes spinning in opposite directions, was adopted in Beznos et al. [9] to balance a bicycle. The authors therein controlled the precession of the gyroscopes to generate a gyroscopic torque to counteract the destabilizing gravitational torque. Lee and Ham [10] proposed a load mass system to balance the bicycle. The control strategy was developed to turn the bicycle system left or right by moving the center of a load mass accordingly. A well-known self-balancing robot bicycle, Murata Boy, was developed by Murata in 2005 [11]. Murata Boy contains a reaction wheel whose speed change generates a reaction torque to balance the bicycle.
Attitude guidance and tracking for spacecraft with two reaction wheels
Published in International Journal of Control, 2018
James D. Biggs, Yuliang Bai, Helen Henninger
This paper is motivated by a trend towards the miniaturisation of spacecraft to reduce launch and operational costs of certain missions. In particular, there is currently a significant interest in the use of nano-spacecraft (1–10 kg) for undertaking Earth observation and space science missions. One aspect to enhance the possibility of further miniaturisation capability is to reduce the mass, power and volume requirements of the sub-systems, for example, by using less actuators. Moreover, a nano-sized reaction wheel (RW) can weigh around 0.2 − 0.3 kg thus accounting for up to 30% of a nano-spacecraft's total mass. Thus, reducing the number of RWs without significantly reducing control performance could help to optimise system design. In addition, nano-spacecraft carries a much higher risk of failure than conventional spacecraft and thus contingency control algorithms must be designed to cope with actuator failure. This paper addresses the problem of optimally re-pointing a spacecraft underactuated in attitude control and thus could be useful in the event of RW failures where only two are operational.