Prescribed contact establishment of a robot with a planar surface under position and stiffness uncertainties

The problem of motion planning in obstacle cluttered environments is an important task in robotics. In the literature several methodologies exist to address the problem. In this work we consider using the feedback-based approach, where the solution comes from designing a controller capable of guaranteeing trajectory tracking with obstacle avoidance. Commonly, all respective studies consider simplified robot dynamics, which is usually insufficient in practical applications.In this work we focus on the collision avoidance problem with respect to a moving spherical object. We assume knowledge of a nominal controller that achieves tracking of a desired trajectory in the absence of obstacles, and we design an auxiliary control scheme to guarantee that the robot's end-effector will always operate in a safe distance from the moving obstacle's surface. The controller we develop does not take into account the actual robot dynamics, thus constituting a truly model-free approach. Experimental studies conducted on a KUKA LWR4+ robotic manipulator clarify and verify the proposed control scheme.

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“…Differentiating V 1 with respect to time, employing (16) and via straightforward algebraic manipulation, it is obtained,…”

Section: Proof Of Theoremmentioning

confidence: 99%

Improving Safety in Human-Robot Collaboration via Dynamic Active Constraints Enforcement

Kanakis

Rovithakis

2021

2021 30th IEEE International Conference on Robot &Amp; Human Interactive Communication (RO-MAN)

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“…Indicative applications of PPC include visual servoing [16], tracking of rigid, revolute joint manipulators [17], [18], control of robots having elastic joint [19] and variable stifness actuators [20], force/position control of robots [21], [22], control of underwater vehicles [23], [24], control of aerial vehicles [25], human-robot safety [26], active constraints satisfaction [27], physical human robot interaction [28], and guaranteeing rolling and avoiding sliding of robotic fingures [29].…”

Section: Non-adaptive Prescribed Performance Controlmentioning

confidence: 99%

Prescribed Performance Adaptive Control of Uncertain Nonlinear Systems: State‐of‐the‐art and Open Issues

Rovithakis

2018

Proc Appl Math and Mech

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Performance in adaptive control designs for uncertain nonlinear systems, whose uncertainty is not purely parametric, was traditionally restricted to enforcing, besides stability, desirable behavior at steady-state. In the literature, rigorous proofs have been provided guaranteeing tracking error convergence to residual sets, whose size depends on design parameters and some bounded though unknown terms. Therefore, even controllable, steady-state accuracy was impossible to be a priori selected by any systematic procedure. Furthermore, transient performance such as maximum overshoot and convergence rate, was difficult to be established analytically even for known systems. The problem was approached via minimizing certain performance indices, which unfortunately were connected only indirectly with the actual system response. Hence, even though performance improvement is anticipated, no connection to a priori specified trajectory oriented metrics could be achieved. For classes of nonlinear systems Funnel Control has been proposed to provide solution. However, the problem remained largely unsolved for the case of adaptive closed-loop uncertain systems. To fill in the gap, the Prescribed Performance Control (PPC) methodology was presented. This work is a review on PPC, highlighting on its main advantages and discussing on probably the most important open issues.

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“…These developed methods make it possible for designers to set the convergence rate, overshoot, and steady-state errors in advance. The latest PPC research results so far mainly include theoretical applications [24], engineering applications [25], [26], and theoretical extensions [27], all of which use PPC to provide a performance guarantee.…”

Section: Introductionmentioning

confidence: 99%

“…In fact, by using the valid points on the performance function curves and attaching some reasonable definitions, the maximum settling time can be intuitively expressed. Using a new continuous performance function instead of the original asymptotic performance function [26], a convenient and effective control algorithm for pre-defined maximum settling time (PMST) may be designed. Based on the above considerations, we list the main motivations as follows.…”

Section: Introductionmentioning

confidence: 99%

Finite-Time Control for 6-DOF Coupling On-Orbit Service Spacecraft With Pre-Defined Maximum Settling Time Guaranteed

Gao

2021

IEEE Access

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In this paper, for the precise relative motion control of the 6-DOF on-orbit service spacecraft, motivated by discovering a proper method to flexibly adjust the settling time before the control system design, a constraint function is proposed. Considering the ability of pre-defined performance techniques to pre-design response behaviors, a relevant control named by Pre-defined Maximum Settling Time Control (PMSTC) is investigated. Under the proposed framework, a PMSTC for spacecraft systems is designed with the aid of the power integrator-adding technique. The proposed controller allows us to design the response performance of a closed-loop system in advance, e.g., maximum settling time, maximum steady-state error, and maximum overshoot. More importantly, the PMSTC is able to separate the coupling of the settling time and the choosing of control parameters, which thus alleviate the complexity of the control design. The closed-loop system of the 6-DOF spacecraft showcases the full power of this approach, based on which, the rationality and effectiveness of the algorithm have been verified. To illustrate the characteristics of this algorithm, this paper compares the proposed algorithm with some state-of-the-art algorithms and analyzes the effect of parameters in detail.

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Prescribed contact establishment of a robot with a planar surface under position and stiffness uncertainties

Cited by 17 publications

References 20 publications

Improving Safety in Human-Robot Collaboration via Dynamic Active Constraints Enforcement

Improving Safety in Human-Robot Collaboration via Dynamic Active Constraints Enforcement

Prescribed Performance Adaptive Control of Uncertain Nonlinear Systems: State‐of‐the‐art and Open Issues

Finite-Time Control for 6-DOF Coupling On-Orbit Service Spacecraft With Pre-Defined Maximum Settling Time Guaranteed

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