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Controlling of a space robot without actuators on the main body is an underactuated control problem. As stabilization methods, time-varying feedback controllers, discontinuous feedback controllers, center manifold based methods, zero-dynamics methods, and sliding mode controllers have been proposed. However, these methods sometime suffer from slow...
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The trajectory tracking and vibration suppression of elastic base and two flexible arms for a free-floating space robot system with flexible arms and elastic base is discussed. Using singular perturbation theory of two kinds of time scale, a slow-subsystem describing the rigid motion and a fast-subsystem corresponding to vibration of base elastic a...
Citations
Based on the concept of reaction null-space, a new distributed momentum control is proposed. The new scheme guarantees the stability of carrier attitude and the convergent property of end-effector tracking error during space manipulator capturing object. When the dynamic parameters contain errors or changes caused by the payload, according to online parameter identification an adaptive scheme is developed to avoid the effect of parameters errors on the carrier attitude, achieve trajectory tracking of the end-effector, and then accommodate various non-modeled disturbances simultaneously. Finally, simulation result confirms the effectiveness of the algorithm.
Underactuated control problems, such as the control of a space robot without actuators on the main body, have been widely investigated. However, few studies have examined attitude control problems of underactuated space robots equipped with a flexible appendage, such as solar panels. In order to suppress vibration in flexible appendages, a zero-vibration input-shaping technique was applied to the link motion of an underactuated planar space robot. However, because the vibrational frequency depends on the link angles, simple input-shaping control methods cannot sufficiently suppress the vibration. In this paper, the dependency of the vibrational frequency on the link angles is measured experimentally, and the time-delay interval of the input shaper is then tuned based on the frequency estimated from the link angles. The proposed control method is referred to as frequency-tuning input-shaped manifold-based switching control (frequency-tuning IS-MBSC). The experimental results reveal that frequency-tuning IS-MBSC is capable of controlling the link angles and the main body attitude to maintain the target angles and that the vibration suppression performance of the proposed frequency-tuning IS-MBSC is better than that of a non-tuning IS-MBSC, which does not take the frequency variation into consideration.
Control of a space robot without actuators on the main body is an
underactuated control problem. Various stabilization methods, such as
the time-varying feedback control method, discontinuous feedback control
method, center manifold-based method, zero-dynamics method and
sliding-mode control method have been proposed. However, past studies
have not considered underactuated space robots equipped with a flexible
appendage, such as solar panels. If the manipulators are simply
controlled to achieve the target state for the robot using the past
controllers without taking a flexible appendage into consideration,
residual vibration remains even after the link motion has finished. In
order to suppress the residual vibration on the flexible appendage, we
apply the input-shaping technique to the link motion of an underactuated
planar space robot. Numerical and experimental studies are carried out
to validate the proposed method for a planar dual-link space robot with
a flexible appendage. The results show that the proposed method is
capable of not only controlling the link angles and the main body
attitude to the goal angles, but also suppressing the residual vibration
on the flexible appendage.
