Dynamic stabilization of thin aperture light collector space telescope using active rods

High performance control requires high loop gain and large control bandwidth. However, the spurious resonances at the higher frequencies can limit the performance of such type of systems. This drawback can be overcome by using sensor fusion technique. In sensor fusion, two or more sensors are combined in synergy such that good performance is achieved at lower frequencies while ensuring robustness of the system at higher frequencies. This paper presents a new technique, termed as ''virtual sensor fusion", in which only one of the sensors is physically installed on the system while the other sensor is simulated virtually. The virtual sensor is selected based on desired high frequency response. The effectiveness of the proposed technique is demonstrated numerically for a case of active seismic isolation. A robustness analysis of virtual sensor fusion is also carried out in order to study its stability in the presence of spurious resonances. Finally, the technique is experimentally verified on active isolation of pendulum system from ground motion. The results obtained demonstrate good isolation performance at lower frequencies and robustness to plant uncertainties (spurious resonances) at higher frequencies. This technique can be effectively used for high precision control of sensitive instruments.

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“…where transfer functions G 3 and G 4 can be obtained by substituting Eq. (11) in (10). The transfer function from u to y (G u ) in Fig.…”

Section: An Example Of Active Vibration Isolation Using Virtual Sensomentioning

confidence: 99%

“…Also, there are certain applications which require both active isolation and pointing control. For example, microvibration control for high pointing accuracy in space systems [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Virtual sensor fusion for high precision control

Verma

Dehaeze

Zhao

et al. 2021

Mechanical Systems and Signal Processing

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“…The cubic configuration of a Stewart platform has equal control authority in all the degrees of freedom [33]. The velocities of the isolation legs are related to the velocities of the payload plate by a Jacobian matrix (refer equations (13) and (23)).…”

Section: A Geometric Configurationmentioning

confidence: 99%

Multi-Degree of Freedom Isolation System With High Frequency Roll-Off for Drone Camera Stabilization

et al. 2020

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The technological developments in the field of image based sensing have led to a vast growth in the use of drones in various domains. The drone is usually equipped with an image sensor (camera) which collect images over the target area. These images are then post-processed to extract the important information. Efficiency and accuracy of the image based sensing are largely dependent on the captured image quality. Therefore, it is important to prevent the transmission of the drone vibrations to the camera. Most of the current camera mounting systems use passive rubber mounts for isolation. However, these mounts are effective only in vertical direction and essentially adds damping to the system which degrades the performance of the isolation at high frequency. In this paper, a multi-degree of freedom isolation system, based on a Stewart platform configuration, is proposed for drone camera stabilization. The important features of the proposed isolation system are-(i) high frequency roll-off, (ii) no use of flexible joints, (iii) uses non-contact voice coil actuator thus avoiding spurious resonances of the legs, (iv) adjustable stiffness, (v) 3D printed lightweight parts and (vi) centralized control using a single sensor (inertial measurement unit). A prototype of the proposed system has been manufactured and validated experimentally. The proposed isolation system is found to reduce the response of the isolation system near resonance without compromising performance at high frequency. The application of the isolation system can be easily extended to other fields which require high quality image acquisition.

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“…External disturbances like ground motion or environmental disturbances can greatly affect the performance of the sensitive equipment. Active systems can be used to isolate the equipment from the external disturbances [1]. Sensors and actuators in many active systems are often collocated in order to build robustness into the system.…”

Section: Introductionmentioning

confidence: 99%

Perfect collocation using self-sensing electromagnetic actuator: Application to vibration control of flexible structures

Verma

Lafarga

Collette

2020

Sensors and Actuators A: Physical

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Collocated control has the advantages of robustness and guaranteed stability. In collocated control, the sensor and actuator are placed close to each other. True collocation can be achieved using self-sensing in which the actuator can also be used as a sensor. In this article, we present a self-sensing electromagnetic actuator for vibration control of flexible structures. The back electromotive force (emf) generated in the coil is measured to evaluate the velocity of the structure (and hence, the displacement). The position measurements obtained from self-sensing are found to have good correlation with those obtained using an eddy current sensor. The efficacy of the proposed technique has been verified for the vibration control of a flexible cantilever beam. Self-sensing offers economical, simple and robust control architecture. It can be effectively used for applications where sensors and actuators cannot be collocated due to space and size limitations.

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Dynamic stabilization of thin aperture light collector space telescope using active rods

Cited by 3 publications

References 21 publications

Virtual sensor fusion for high precision control

Virtual sensor fusion for high precision control

Multi-Degree of Freedom Isolation System With High Frequency Roll-Off for Drone Camera Stabilization

Perfect collocation using self-sensing electromagnetic actuator: Application to vibration control of flexible structures

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