Compliant Floating-Base Control of Space Robots

Giordano, Alessandro M.; Calzolari, Davide; Stefano, Marco De; Mishra, Hrishik; Ott, Christian; Albu‐Schäffer, Alin

doi:10.1109/lra.2021.3097496

Cited by 6 publications

(3 citation statements)

References 24 publications

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“…Robotic technologies can be used in space operation missions such as capturing an inactive satellite or deorbiting space debris [1]. However, the dynamics and control of a space robot are complex [2,3]. It is necessary to validate the design and control of space operations on the ground [4,5].…”

Section: Introductionmentioning

confidence: 99%

Active Compliance Control of a Position-Controlled Industrial Robot for Simulating Space Operations

Shen

Gao

et al. 2022

Chin. J. Mech. Eng.

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An industrial robot with a six-axis force/torque sensor is usually used to produce a zero-gravity environment for testing space robotic operations. However, using traditional force control methods, such as admittance control, causes position-controlled industrial robots to undergo from force divergence owing to intrinsic time delay. In this paper, a new force control method is proposed to eliminate the force divergence. A hardware-in-the-loop (HIL) simulator with an industrial robot is first presented. The free-floating satellite dynamics and the motion mapping from the satellites to simulator are both established. Thus, the effects of measurement delay and dynamic response delay on contact velocity and force are investigated. After that, a real-time estimation method for contact stiffness and damping is proposed based on the adaptive Kalman filter. The measurement delay is compensated by a phase lead model. Moreover, the identified contact parameters are adopted to modify contact forces, and thus the dynamics response delay can be compensated for. Finally, a co-simulation and experiments were conducted to verify the force control method. The results show that contact stiffness and damping could be identified exactly and that the simulation divergence could be prevented. This paper proposes an active compliance control method that can deal with force constrained tasks of a position-controlled robot in unknown environments.

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Section: Introductionmentioning

confidence: 99%

Active Compliance Control of a Position-Controlled Industrial Robot for Simulating Space Operations

Shen

Gao

et al. 2022

Chin. J. Mech. Eng.

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“…They are widely used in space operations [1,2] and play an important role in the construction process of the space station [3]. In recent years, with the increasing demand for space manipulation accuracy, high-precision control of space robots draws attention [4,5]. As non-negligible factors affecting control accuracy, the topic of flexibilities in the base, link and joint on space robot becomes an important subject.…”

Section: Introductionmentioning

confidence: 99%

Integrated sliding mode control with input restriction, output feedback and repetitive learning for space robot with flexible-base, flexible-link and flexible-joint

Chen

2022

Robotica

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In the control of space robots, flexible vibrations exist in the base, links and joints. When building a motion control scheme, the following three aspects should be considered: (1) the complexity in dynamic modeling; (2) the low accuracy of motion control and (3) the simultaneous suppression of multiple flexible vibrations. In this paper, we propose a motion vibration integrated saturation control scheme. First, the dynamic model of space robot with flexible-base, flexible-link and flexible-joint is established according to the assumed modes method and Lagrange equation. Second, singular perturbation theory is used to decompose the model into two subsystems: a slow subsystem containing the rigid motions of base and joints as well as the vibration of links, and a fast subsystem containing vibrations of base and joints. Third, an integrated sliding mode control with input restriction, output feedback and repetitive learning (ISMC-IOR) is designed, which can track the desired trajectories of base and joints with −3 orders of magnitude accuracy, while suppressing the multiple flexible vibrations of base, links and joints 50%–80% and 37% performance improvement over ISMC-IOR-NV were achieved. Finally, the algorithm is verified by simulations.

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“…Tracking control is particularly important for space robotics applications, where the goal is to enable the base and joints to track up the desired trajectory with the desired dynamic performance. In recent decades, various space robot control methods have emerged [18,19]. However, because the fully flexible space robot has time-varying, rigidflexible strong coupling, highly nonlinear and other characteristics, traditional PID control, feedback control and other factors struggle to meet its high-precision requirements, and for the ordinary rigid motion controller, because it cannot suppress the system multiple flexible vibration, control failure of fully flexible system is easy to trigger.…”

Section: Introductionmentioning

confidence: 99%

Integrated Fixed Time Sliding Mode Control for Motion and Vibration of Space Robot with Fully Flexible Base–Link–Joint

Chen

2021

Applied Sciences

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The dynamic modeling, motion control and flexible vibration active suppression of space robot under the influence of flexible base, flexible link and flexible joint are explored, and motion and vibration integrated fixed-time sliding mode control of fully flexible system is designed. The flexibility of the base and joints are equivalent to the vibration effect of linear springs and torsion springs. The flexible links are regarded as Euler–Bernoulli simply supported beams, which are analyzed by the hypothetical mode method, and the dynamic model of the fully flexible space robot is established by using the Lagrange equation. Then, the singular perturbation theory is used to decompose the model into slow subsystem including rigid motion and the link flexible vibrations, and fast subsystems including the base and the joint flexible vibrations. A fixed time sliding mode control based on hybrid trajectory is designed for the slow subsystem to ensure that the base and joints track the desired trajectory in a limited time while achieving vibration suppression on the flexible links. For the fast subsystem, linear quadratic optimal control is used to suppress the flexible vibration of the base and joints. The simulation results show that the controller proposed in the paper can make the system state converge within a fixed time, is robust to model uncertainty and external interference, and can effectively suppress the flexible vibration of the base, links, and joints.

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Compliant Floating-Base Control of Space Robots

Cited by 6 publications

References 24 publications

Active Compliance Control of a Position-Controlled Industrial Robot for Simulating Space Operations

Active Compliance Control of a Position-Controlled Industrial Robot for Simulating Space Operations

Integrated sliding mode control with input restriction, output feedback and repetitive learning for space robot with flexible-base, flexible-link and flexible-joint

Integrated Fixed Time Sliding Mode Control for Motion and Vibration of Space Robot with Fully Flexible Base–Link–Joint

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