Wave-Based Control of a Mass-Restricted Robotic Arm for a Planetary Rover
Here wave-based control is applied to suppress vibrations during repositioning of a flexible robotic arm on a planetary rover in a Martian environment. Typically, such a robotic arm has very low power and mass budgets, implying significant flexibility, wi
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Abstract Here wave-based control is applied to suppress vibrations during repositioning of a flexible robotic arm on a planetary rover in a Martian environment. Typically, such a robotic arm has very low power and mass budgets, implying significant flexibility, with static and dynamic consequences. Meeting precision performance specifications then becomes challenging and active vibration control is required. The example of the DExtrous LIghtweight Arms for exploratioN (DELIAN) arm is the focus of this paper. DELIAN is a general purpose arm, currently in development by SELEX ES for the European Space Agency (ESA). For active vibration control, a wave-based controller is used: a strategy formulated specifically for flexible mechanical systems. It considers actuator motion as launching and absorbing mechanical waves into and from the system. Absorbing the returning wave provides effective, active vibration damping while simultaneously moving the system to the target displacement. It is robust to both actuator performance and modelling errors, very stable, and easy to implement. The controller was found to perform well in limiting the effect of the flexibility during manoeuvres and also when rejecting vibrations due to impacts.
1 Introduction Robotic arms play an important role in space, from large arms deployed in microgravity environments, such as the Canadarm upon the ISS, to smaller arms on planetary rovers. Typically, the arm specification has very low power and mass budgets, and the lighter the structure the more flexible it becomes. This elasticity has consequences for both the dynamics and the static deflections. Meeting the precision performance specifications then becomes challenging and a strategy for active control of the vibrations is required. D.J. McKeown (✉) ⋅ W.J. O’Connor School of Mechanical and Materials Engineering, University College Dublin, Belfield, Dublin 4, Ireland e-mail: [email protected] © Springer International Publishing Switzerland 2016 J. Awrejcewicz (ed.), Dynamical Systems: Theoretical and Experimental Analysis, Springer Proceedings in Mathematics & Statistics 182, DOI 10.1007/978-3-319-42408-8_19
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D.J. McKeown and W.J. O’Connor
In this paper we take the example of the DExtrous LIghtweight Arms for exploratioN (DELIAN) arm. DELIAN is a general purpose arm, currently in development by SELEX ES for the European Space Agency (ESA). Its design allows for many configurations for different operating scenarios. Here we consider the scenario of a planetary rover vehicle with an arm designed to pick up and place scientific instruments, but where the arm mass is tightly constrained. The combination of arm length and payload mass gives this implementation the lowest natural frequencies and therefore the greatest need for active vibration damping. Another configuration envisages using the arm for surface drilling, with a tool attached at the end effector, which would also give rise to system vibrations. To provide active control of the vibrations, a wave-based controller is designed and impl
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