Online Identification of Environment Hunt–Crossley Models Using Polynomial Linearization

Schindeler, Ryan; Hashtrudi-Zaad, Keyvan

doi:10.1109/tro.2017.2776318

Cited by 25 publications

(11 citation statements)

References 33 publications

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“…The maximum displayed stiffness 𝛼𝛼 (25) is 453 N/m. The 𝑔𝑔(𝑘𝑘 𝑑𝑑𝑑𝑑𝑑𝑑 ) and 𝛼𝛼 are used for the controller 𝐶𝐶 1 as in ( 27)- (30). The ISS region in Fig.…”

Section: Methodsmentioning

confidence: 99%

Control of Haptic Systems Based on Input-to-State Stability

Kimand

Lee

2022

IEEE Access

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Discretization of signals often generates additional energy in the haptic systems, and makes them unstable. The currently popular controls based on the passivity stabilize the systems by limiting the rendered force of the haptic systems so that the generated energy from the system stays below zero. The passivity-based methods are, however, often conservative and sacrifice the performance of haptic rendering. This paper proposes a control method to adjust the change rate of the stiffness of virtual environment connected to the haptic systems to satisfy the input-to-state stability (ISS) for better stability and transparency. The ISS conditions for the systems are derived by modeling the system as a linear time-varying system. The systems become dissipative if they satisfy the ISS conditions. The generated surplus energy of the dissipative system is less than a positive finite value while maintaining the stability. Since the passive system is a special case of the dissipative system, the proposed ISS-based control is less conservative than the passivity-based approaches. Performance of the proposed control is experimentally compared with the virtual coupling and the force-bounding method that are widely used passivity-based approaches. The energy generated from the system using the proposed method is positive finite whereas the generated energy using the passivity-based approaches is less than zero. This means that more energy is transferred to the operator. Increased stiffness corresponding to this additionally transferred energy can be rendered. Root-mean-square and maximum errors of the rendered forces are, therefore, reduced by at least 86 % and 50 %, respectively.

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Section: Methodsmentioning

confidence: 99%

Control of Haptic Systems Based on Input-to-State Stability

Kimand

Lee

2022

IEEE Access

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“…The slave is controlled to track the master position. The model stiffness is estimated using the recursive-leastsquare algorithm with an exponential forgetting factor [43], [44] that have been widely used to estimate time-varying parameters. The time delay between the master and the slave is virtually added.…”

Section: Methodsmentioning

confidence: 99%

Adaptive Model-Mediated Teleoperation for Tasks Interacting With Uncertain Environment

Kim

Lee²

2021

IEEE Access

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Model-mediated teleoperation (MMT) employs an environment model at the master side to compute feedback output to the master at a faster rate. This approach improves system stability in the presence of time delay. MMT, however, does not generally perform well if the employed model is not accurate. Model mismatch is unavoidable when the environment is unknown in advance or varies. This paper proposes MMT employing an adaptive model. The proposed method adaptively moves the reference point of the employed model, whereas the previous MMTs used reference points fixed to the surface of objects in the environment. This can make system stability independent of the time delay. Experiments show that the proposed method improves stability compared to the previous MMTs when there are model mismatches. User studies are conducted to compare the operator's performance in two tasks, control of force exerted to objects in the environment, and discrimination of object stiffness. The result shows that the error in the forces applied to objects in the environment significantly decreases in the proposed method. Errors in forces rendered to the master are also improved by at least 20.2 %. The experiment result also shows that subjects can discriminate up to 40.9 % smaller differences in the stiffness than the previous MMT under the same time delay.

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“…The environment can be represented as a spring-damper model [23], [29]. This model is considered to be well-suited for a stiff environment [38]. As shown in Fig.…”

Section: A System Configurationmentioning

confidence: 99%

Reduction of Contact Force Fluctuation for Rotary Wear Test Apparatus

Yokoyama

Shimono

Yamashita

et al. 2020

IEEE/ASME Trans. Mechatron.

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In electric railway systems, wear of current collector devices leads to high maintenance cost. To develop a cost reduction methodology, the wear behavior of current collector materials needs to be fully investigated. However, the wear test apparatuses currently in use cannot control the contact force between materials, and the contact force fluctuates. It is difficult to classify accurate conditions of a wear transition under contact force fluctuation. To solve this problem, we propose a force control system with acceleration and velocity feedbacks to suppress the force fluctuation. The positive feedback of acceleration compensates the periodic force fluctuation at frequencies according to the sliding velocity of rubbing surfaces. The velocity feedback compensates the force fluctuation caused by resonance. The proposed control system is validated by experiments using a prototype of a rotary wear test apparatus.

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Online Identification of Environment Hunt–Crossley Models Using Polynomial Linearization

Cited by 25 publications

References 33 publications

Control of Haptic Systems Based on Input-to-State Stability

Control of Haptic Systems Based on Input-to-State Stability

Adaptive Model-Mediated Teleoperation for Tasks Interacting With Uncertain Environment

Reduction of Contact Force Fluctuation for Rotary Wear Test Apparatus

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