Wave Variable Based Force Control

2007 ◽  
Author(s):  
J. Scot Hart ◽  
Gu¨nter Niemeyer
Keyword(s):  
Time Delay ◽  
Force Control ◽  
Time Delays ◽  
Communication Channel ◽  
Force Feedback ◽  
Low Frequency ◽  
Force Sensor ◽  
Wave Variable ◽  
Communication Time ◽  
Frictional Forces

Wave variable controllers maintain passive communication across time delays in telerobotics. As passive elements, wave variable controllers interact well with other passive elements, such as P.D. controllers and masses, and use a combination of force and velocity signals to apply force feedback. Currently we are exploring the use of wave variable controllers with large non-backdrivable industrial-type slave devices where dynamics are dominated by inertial and frictional forces. The objective is to integrate force sensor measurements into wave variable controllers to provide low frequency force feedback and hide the slave’s friction and inertia from the user in the presence of a communication time delay. This paper presents and uses a wave variable based approach to design force control. The resulting wave variable based force controller is converted to power variables and shown to be similar to traditional force controllers. A 1-DOF telerobotic system is used to experimentally show the wave variable based force control combines with the enhanced stability properties of the wave communication channel to produce robust slave side force control. The resulting system is better able to maintain force control with rigid environments then a traditional controller both with and without communication time delay.

Containment control of second-order multi-agent systems with directed topology and time-delays

Kybernetes ◽  
2014 ◽  
Vol 43 (8) ◽  
pp. 1248-1261 ◽  
Author(s):  
Bin Qi ◽  
Xuyang Lou ◽  
Baotong Cui
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Second Order ◽  
Multi Agent Systems ◽  
Containment Control ◽  
Content Type ◽  
Directed Topology ◽  
Agent Systems ◽  
Communication Time ◽  
Multi Agent

Purpose – The purpose of this paper is to discuss the impacts of the communication time-delays to the distributed containment control of the second-order multi-agent systems with directed topology. Design/methodology/approach – A basic theoretical analysis is first carried out for the containment control of the second-order multi-agent systems under directed topology without communication time-delay and a sufficient condition is proposed for the achievement of containment control. Based on the above result and frequency-domain analysis method, a sufficient condition is also derived for the achievement of containment control of the second-order multi-agent systems under directed topology with communication time-delays. Finally, simulation results are presented to support the effectiveness of the theoretical results. Findings – For the achievement of containment control of the second-order multi-agent systems under directed topology with communication time-delay, the control gain in the control protocols is completely dependent on the communication topology structure and the maximum of time-delay in the control protocols is dependent on the given control gain and communication topology structure. Originality/value – The paper investigates the containment control of the second-order multi-agent systems under directed topology with communication time-delays and presents a sufficient conditions for the achievement of containment control. The results and approach proposed in the paper may benefit interesting researchers.

Constant Visual and Haptic Time Delays in Simulated Bilateral Teleoperation: Quantifying the Human Operator Performance

2013 ◽  
Vol 22 (4) ◽  
pp. 271-290 ◽  
Author(s):  
Tariq Abuhamdia ◽  
Jacob Rosen
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Human Performance ◽  
Force Feedback ◽  
Bilateral Teleoperation ◽  
Haptic Information ◽  
Position Errors ◽  
Pick And Place ◽  
Place Task ◽  
Two Delays

Visual feedback and force feedback (haptics) are the two streams of information in a robotic bilateral teleoperation where the operator manipulates a robot in a remote location. Delivering the visual and the haptic information depends in part on the characteristics of the communication network and results in a nonsynchronized delay. The goal is to study the effect of constant nonsynchronized and synchronized time delay of visual and haptic information on the human teleoperation performance. The experimental setup included a virtual reality environment, which allows the operator to manipulate the virtual objects in a simulated remote environment through a haptic device that renders the force feedback. The visual and the haptic information were delayed independently in the range of 0–500 ms, creating 121 different scenarios of synchronized and nonsynchronized delays. Selecting specific parameters of the remote virtual environment guaranteed stable teleportation, given the time delays under study. The experimental tasks included tracing predefined geometrical shapes and a pick-and-place task, which simulates both structured and unstructured interactions under the influence of guiding forces. Eight subjects (n = 8) participated in the experiment performing three repetitions of three different teleoperation tasks with 121 combinations of visual and haptic time delays. The measured parameters that were used to assess the human performance were the task completion time and the position errors expressed as a function of the visual and the haptic time delay. Then, regression and ANOVA analyses were performed. The results indicated that the human performance is a function of the sum of the two delays. As the sum of the two delays increases, the human performance degrades and is expressed with an increase in completion time and position errors. The performance degradation is more pronounced in the pick-and-place task compared to the tracing task. In scenarios where the visual and the haptics information were out of synchronization, the human performance was better than intentionally delaying one source of information in an attempt to synchronize and unify the two delays. The results of this study may be applied to any teleoperation tasks over a network with inherent time delays and more specifically to telesurgery in which performance degradation due to time delay has a profound effect on the quality of the healthcare delivered, patient safety, and ultimately the outcomes of the surgical procedure itself.

Bilateral Teleoperation With Time Delay Using Modified Wave Variable Based Controller

2009 ◽  
Author(s):  
K. Kawashima ◽  
K. Tadano ◽  
M. S. Fofana
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Degrees Of Freedom ◽  
Critical Time ◽  
Wave Impedance ◽  
Surgical Robot ◽  
Surgical Robots ◽  
Cumulative Energy ◽  
Wave Variable ◽  
Force Tracking

Very often in teleoperation of surgical robots, we discover that there is some degree of uncertainty in terms of locating critical time delays necessary to establish criteria sustaining stable and safe surgical regimes. Within the stable and safe regimes optimal performance indices and critical time delays combine to deliver a greater motion rhythm for the teleoperation of surgical robots. In this paper, we apply a bilateral controller of the modified wave variable (MWV) type to locate critical time delays maintaining stable and safe teleoperation of a specific surgical robot. The controller implemented additional wave impedance in the wave variable transformations in order to focus more closely on force tracking. The effectiveness of the proposed controller and locate dynamics of specific phenomena that align with the cumulative energy density required to operate the surgical robot are investigated. Firstly, the stability of MWV is investigated in detail. Then, the effect of additional wave impedance is discussed theoretically. Finally, experiments are conducted for three degrees of freedom master and slave manipulators to demonstrate the effectiveness of the MWV. The controller provides superior position and force tracking performance compared to the traditional wave variable-based method. The proposed method can improve position and force tracking errors between the master and slave caused by the communication channel time delay.

scholarly journals Additive Mixed Sensitivity Design of PID Controllers for Continuous-Time System with Uncertain Time-Delay

2021 ◽  
Vol 20 ◽  
pp. 303-311
Author(s):  
Tooran Emami
Keyword(s):  
Time Delay ◽  
Continuous Time ◽  
Time Delays ◽  
Dc Motor ◽  
Internal Communication ◽  
Pid Controllers ◽  
Time System ◽  
Communication Time ◽  
Uncertain Time ◽  
Continuous Time System

This paper presents an algorithm for all achievable coefficients of Proportional Integral Derivative (PID) controllers in an integral-derivative plane that stabilizes and satisfies additive mixed sensitivity constraint with an uncertain time delay for a continuous-time system. This algorithm solves the singularity problem of designing PID controllers in the integral and derivative plane and estimates achievable ranges of proportional gain of the PID controllers. A numerical cascaded ball and beam with unity feedback control of an SRV-DC motor and uncertain communication time delays in the system process demonstrate the application of this methodology. In this application, the additive weight bounds the additive errors for the cascaded ball and beam and the closed-loop SRV-DC motor system transfer function with the internal communication time delays

scholarly journals Weighted Couple-Group Consensus Analysis of Heterogeneous Multiagent Systems with Cooperative-Competitive Interactions and Time Delays

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Xingcheng Pu ◽  
Chaowen Xiong ◽  
Lianghao Ji ◽  
Longlong Zhao
Keyword(s):  
Time Delay ◽  
Multiagent Systems ◽  
Time Delays ◽  
Multiagent System ◽  
Experimental Simulation ◽  
Group Consensus ◽  
Consensus Protocol ◽  
Consensus Analysis ◽  
Communication Time ◽  
Nyquist Criterion

In this paper, the weighted couple-group consensus of continuous-time heterogeneous multiagent systems with input and communication time delay is investigated. A novel weighted couple-group consensus protocol based on cooperation and competition interaction is designed, which can relax the in-degree balance condition. By using graph theory, general Nyquist criterion and Gerschgorin disc theorem, the time delay upper limit that the system may allow is obtained. The conclusions indicate that there is no relationship between weighted couple-group consensus and communication time delay. When the agents input time delay, the coupling weight between the agents, and the systems control parameters are satisfied, the multiagent system can converge to any given weighted coupling group consistent state. The experimental simulation results verify the correctness of the conclusion.

A Control Method for Robot Fingers with Three-Axis Force Sensor

2014 ◽  
Vol 614 ◽  
pp. 175-178
Author(s):  
Ming Hua Luo ◽  
Chun Wei Pan ◽  
Xiu Wen Yang ◽  
Xin Hua Luo
Keyword(s):  
Control System ◽  
Force Control ◽  
Force Feedback ◽  
Control Method ◽  
Dynamic Balance ◽  
Force Sensor ◽  
Robot Hand ◽  
Closed Loops ◽  
Force Control System ◽  
Grasping Force

This paper proposed a new grasping method for robot fingers with three-axis force sensors. When a robot hand with two fingers is grasping an object, such as an egg, two closed loops with negative feedback in force-control system are start. When grasping force of the two fingers are equal reference force, dynamic balance is reached. Once tiny sliding between egg and finger occurred, force feedback start immediately, dynamic balance is reached again. In this way, our robot hand can firmly grasps eggs, even if vibration added on the robot hand.

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