Contact force estimation for backdrivable robotic manipulators with coupled friction

Naerum, Edvard; Cornella, J.; Elle, Ole Jacob

doi:10.1109/iros.2008.4651192

Cited by 15 publications

(4 citation statements)

References 13 publications

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“…In the simulations, the presented control scheme is applied to a haptic system model including two Geomagic Touch haptic interfaces [29]. The environment is assumed to have a linear model with stiffness and damping as

K_{\rm e}=10

B_{\rm e}=2

.…”

Section: Resultsmentioning

confidence: 99%

A dual robust control architecture with variable stiffness and damping parameters for switching task dominance in collaborative haptic systems

Motaharifar

Sharifi

Sadeghi

et al. 2023

IET Control Theory & Appl

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In collaborative haptic training systems, a novice operator is interfaced with an expert operator and cooperatively performs some task on a real/virtual environment. Most control architectures for collaborative haptic training systems do not consider the switching task dominance together with investigating overall stability in the presence of nonlinear dynamics and uncertainty. In this paper, a theoretical framework is presented for switching task dominance in collaborative haptic training systems based on supervision and intervention of the expert operator. To that effect, the novice operator performs the operation with as little as possible interference haptic signals in the normal operational conditions. On the other hand, the expert operator is able to intervene the operation to guide the novice operator when it is necessary. The most challenging part of controller design for such systems is to provide the mentioned supervisory framework in a way that the stability of interaction between the operators and the system is ensured with acceptable task performance in various operational conditions. This work offers a variable‐gain dual robust control scheme to address the above problem. The key idea is that the tracking gain of each controller is adjusted in real‐time to switch the task authorities. It is verified that the input‐to‐state stability property is satisfied for each subsystem. Then, the overall stability is proved by leveraging the small gain theorem. Finally, the functionality and performance of the suggested control architecture is demonstrated through simulation and experimental studies.

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K_{\rm e}=10

B_{\rm e}=2

.…”

Section: Resultsmentioning

confidence: 99%

A dual robust control architecture with variable stiffness and damping parameters for switching task dominance in collaborative haptic systems

Motaharifar

Sharifi

Sadeghi

et al. 2023

IET Control Theory & Appl

View full text Add to dashboard Cite

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“…Note that c i = cos(q i ), s i = sin(q i ), c 2.i = cos(2q i ), and s 2.i = sin(2q i ). The inertia matrix of the PHANToM robot, assuming q 2 = 0, is (Naerum et al, 2008):…”

Section: Methodsmentioning

confidence: 99%

Nonlinear disturbance observer design for robotic manipulators

Mohammadi

Tavakoli

Marquez

et al. 2013

Control Engineering Practice

392

224

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Robotic manipulators are highly nonlinear and coupled systems that are subject to different types of disturbances such as joint frictions, unknown payloads, varying contact points, and unmodeled dynamics. These disturbances, when unaccounted for, adversely affect the performance of the manipulator. Employing a disturbance observer is a common method to reject such disturbances. In addition to disturbance rejection, disturbance observers can be used in force control applications. Recently, research has been done regarding the design of nonlinear disturbance observers (NLDOs) for robotic manipulators. In spite of good results in terms of disturbance tracking, the previously designed nonlinear disturbance observers can merely be used for planar serial manipulators with revolute joints (Chen, W.H., Ballance, D.J., Gawthorp, P.J., O'Reilly, J., 2000. A nonlinear disturbance observer for robotic manipulators. IEEE Trans. Ind. Electron. 47, 932-938), (Nikoobin, A., Haghighi, R., 2009. Lyapunov-based nonlinear disturbance observer for serial n-link manipulators. J. Intell. Robot. Syst. 55,[135][136][137][138][139][140][141][142][143][144][145][146][147][148][149][150][151][152][153]. In this paper, a general systematic approach is proposed to solve the disturbance observer design problem for robotic manipulators without restrictions on the number of degrees-of-freedom (DOFs), the types of joints, or the manipulator configuration. Moreover, this design method does not need the exact dynamic model of the serial robotic manipulator. This method also * Corresponding author, Tel.: +1 (647) unifies the previously proposed linear and nonlinear disturbance observers in a general framework. Simulations are presented for a 4-DOF SCARA manipulator to show the effectiveness of the proposed disturbance observer design method. Experimental results using a PHANToM Omni haptic device further illustrate the effectiveness of the design method.

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“…However, their method was based on an assumption that the dynamic wrench is negligible and complete gravity compensation is possible. A hybrid model/learning‐based dynamic equation of a robot was presented in order to draw upon the best features of both model‐ and learning‐based techniques23 because, with accurate knowledge of the dynamics of the robot, interaction forces can be estimated, which makes proper system identification a crucial step to success. It was shown that manual excitation can improve contact force estimation.…”

Section: Introductionmentioning

confidence: 99%