Variable Damping Control of a Robotic Arm to Improve Trade-off between Agility and Stability and Reduce User Effort

Bitz, Tanner; Zahedi, Fatemeh; Lee, Hyunglae

doi:10.1109/icra40945.2020.9196572

Cited by 8 publications

(5 citation statements)

References 9 publications

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“…Rouse et al suggested that negative viscosity in the ankle may facilitate energy storage during early stance phase [25]. Aside from these observations in humans, negative damping in manipulators was found to facilitate generalization motor skill in humans and also facilitate human-robot interaction [20], [22]. The time-varying impedance of the manipulator may be an efficient means of improving energy-storing capabilities of the robot and facilitating its interaction with external objects.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Online Impedance Adaptation Facilitates Manipulating a Whip

Xiong

Nah

Krotov

et al. 2021

2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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Manipulation of flexible objects is one of the major challenges in robotics as the nonlinear dynamics of the high-dimensional object structure makes it difficult to apply current control methods. A previous simulation study showed that control with few pre-structured joint trajectories coupled with joint impedance (dynamic primitives) could control a 25-dimensional whip to hit a target. This was possible even though the impedance values were constant. This paper explores whether time-varying impedance throughout the movement may further enhance performance. We present an online impedance adaptation (OIA) controller that modulates the joint impedances of a two-joint actuator in real time for the same task. Results showed that the OIA control method increased the speed of optimization and resulted in smaller deviation from the zero-torque joint trajectories compared to the controller with constant joint impedances. This novel way to modulate both motion and impedance of a manipulator may facilitate the control of flexible objects with significant dynamics.

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Section: Discussionmentioning

confidence: 99%

“…For instance, time-varying joint impedances for a 14-DOF Baxter Robot enabled a smooth transition from free motion to contact [17]. Other examples can be found in robotics [17]- [19], human-robot interaction [20]- [22] and human motor control [23]- [26].…”

Section: Introductionmentioning

confidence: 99%

Online Impedance Adaptation Facilitates Manipulating a Whip

Xiong

Nah

Krotov

et al. 2021

2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

View full text Add to dashboard Cite

show abstract

“…To ensure that the output of the reference model aligns with the actual output, adaptive control is achieved by adjusting the value of k(t) in the controller through an adaptive mechanism. Now, considering a single-input single-output system, the controlled object and reference model can be represented by dynamic Equations ( 8) and (9).…”

Section: Model Reference Adaptive Controllermentioning

confidence: 99%

“…According to the general approximation theorem, the Szász-Mirakyan operator, as an extension of Bernstein polynomials, can approximate uncertainties, including unmodeled dynamics and external disturbances. In reference [9], the authors proposed a method for the real-time computation of mechanical arm damping using bilateral logic functions, ensuring that the arm's damping remains within an appropriate range. Fuzzy neural networks also find extensive applications in the field of robot control [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Impedance Force Control of Manipulator Based on Variable Universe Fuzzy Control

Kong

Huang

2023

Actuators

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Impedance control is a classic and straightforward control method that finds wide applications in various fields. However, traditional constant impedance control requires prior knowledge of the environment’s stiffness and position information. If the environmental information is unknown, constant impedance control is not capable of handling the task. To address this, this paper proposes a variable universe fuzzy model reference adaptive impedance control method that achieves effective force tracking even in the presence of unknown environmental information. A variable universe fuzzy controller was employed to determine the impedance parameters. The force tracking error and its rate of change were used as two input parameters for the variable universe fuzzy controller, which utilizes fuzzy inference to obtain the incremental values of the impedance parameters. For the introduced model reference controller, a novel adaptive law was employed to obtain the coefficients for contact force and torque. Subsequently, the contact force of the manipulator in Cartesian space was taken as the research object, and a simulation model of a six-joint manipulator was established in MATLAB/Simulink. By comparing it with the constant impedance control method, the feasibility and effectiveness of this control approach were validated.

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“…Ott et al ( 2010 ) proposed a hybrid system that incorporates both controllers in order to achieve: (i) accuracy in free motion and (ii) robust interaction while in contact and free of impacts. Recently, Bitz et al ( 2020 ) investigated the trade-off between agility and stability by proposing a variable damping controller based on user intent. Admittance control is out of the scope of this review and will be partially mentioned.…”

mentioning

confidence: 99%

Variable Impedance Control and Learning—A Review

Abu‐Dakka

Saveriano

2020

Front. Robot. AI

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Robots that physically interact with their surroundings, in order to accomplish some tasks or assist humans in their activities, require to exploit contact forces in a safe and proficient manner. Impedance control is considered as a prominent approach in robotics to avoid large impact forces while operating in unstructured environments. In such environments, the conditions under which the interaction occurs may significantly vary during the task execution. This demands robots to be endowed with online adaptation capabilities to cope with sudden and unexpected changes in the environment. In this context, variable impedance control arises as a powerful tool to modulate the robot's behavior in response to variations in its surroundings. In this survey, we present the state-of-the-art of approaches devoted to variable impedance control from control and learning perspectives (separately and jointly). Moreover, we propose a new taxonomy for mechanical impedance based on variability, learning, and control. The objective of this survey is to put together the concepts and efforts that have been done so far in this field, and to describe advantages and disadvantages of each approach. The survey concludes with open issues in the field and an envisioned framework that may potentially solve them.

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Variable Damping Control of a Robotic Arm to Improve Trade-off between Agility and Stability and Reduce User Effort

Cited by 8 publications

References 9 publications

Online Impedance Adaptation Facilitates Manipulating a Whip

Online Impedance Adaptation Facilitates Manipulating a Whip

Impedance Force Control of Manipulator Based on Variable Universe Fuzzy Control

Variable Impedance Control and Learning—A Review

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