Analytical and Experimental Predictor-Based Time Delay Control of Baxter Robot

2018 ◽  
Author(s):  
Mostafa Bagheri ◽  
Miroslav Krstić ◽  
Peiman Naseradinmousavi
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Input Delay ◽  
Delay Systems ◽  
Engineering Systems ◽  
Common Control ◽  
Pick And Place ◽  
Place Task ◽  
Input Delays ◽  
Time Invariant

In this paper, a predictor-based controller for a 7-DOF Baxter manipulator is formulated to compensate a time-invariant input delay during a pick-and-place task. Robot manipulators are extensively employed because of their reliable, fast, and precise motions although they are subject to large time delays like many engineering systems. The time delay may lead to the lack of high precision required and even catastrophic instability. Using common control approaches on such delay systems can cause poor control performance, and uncompensated input delays can produce hazards when used in engineering applications. Therefore, destabilizing time delays need to be regarded in designing control law. First, delay-free dynamic equations are derived using the Lagrangian method. Then, we formulate a predictor-based controller for a 7-DOF Baxter manipulator, in the presence of input delay, in order to track desirable trajectories. Finally, the results are experimentally evaluated.

Time Delay Control of a High-DOF Robot Manipulator Through Feedback Linearization Based Predictor

2019 ◽  
Author(s):  
Mostafa Bagheri ◽  
Peiman Naseradinmousavi ◽  
Miroslav Krstić
Keyword(s):  
Feedback Linearization ◽  
Robot Manipulator ◽  
Input Delay ◽  
Delay Systems ◽  
Control Laws ◽  
Common Control ◽  
Place Task ◽  
Input Delays ◽  
Time Invariant

Abstract We formulate a predictor-based controller for a high-DOF manipulator to compensate a time-invariant input delay during a pick-and-place task. Robot manipulators are widely used in tele-manipulation systems on the account of their reliable, fast, and precise motions while they are subject to large delays. Using common control algorithms on such delay systems can cause not only poor control performance, but also catastrophic instability in engineering applications. Therefore, delays need to be compensated in designing robust control laws. As a case study, we focus on a 7-DOF Baxter manipulator subject to three different input delays. First, delay-free dynamic equations of the Baxter manipulator are derived using the Lagrangian method. Then, we formulate a predictor-based controller, in the presence of input delay, in order to track desired trajectories. Finally, the effects of input delays in the absence of a robust predictor are investigated, and then the performance of the predictor-based controller is experimentally evaluated to reveal robustness of the algorithm formulated. Simulation and experimental results demonstrate that the predictor-based controller effectively compensates input delays and achieves closed-loop stability.

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.

scholarly journals Identification of LTI Time-Delay Systems with Missing Output Data Using GEM Algorithm

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Xianqiang Yang ◽  
Hamid Reza Karimi
Keyword(s):  
Time Delay ◽  
Linear Time ◽  
Irregular Sampling ◽  
Delay Systems ◽  
Model Parameters ◽  
Delay Model ◽  
Sensor Failure ◽  
Linear Time Invariant ◽  
Failure Data ◽  
Time Invariant

This paper considers the parameter estimation for linear time-invariant (LTI) systems in an input-output setting with output error (OE) time-delay model structure. The problem of missing data is commonly experienced in industry due to irregular sampling, sensor failure, data deletion in data preprocessing, network transmission fault, and so forth; to deal with the identification of LTI systems with time-delay in incomplete-data problem, the generalized expectation-maximization (GEM) algorithm is adopted to estimate the model parameters and the time-delay simultaneously. Numerical examples are provided to demonstrate the effectiveness of the proposed method.

Decentralized controller design by continuous pole placement for neutral time-delay systems

2016 ◽  
Vol 39 (3) ◽  
pp. 297-311 ◽  
Author(s):  
HE Erol ◽  
A İftar
Keyword(s):  
Time Delay ◽  
Controller Design ◽  
Linear Time ◽  
Pole Placement ◽  
Delay Systems ◽  
Time Delay Systems ◽  
Linear Time Invariant ◽  
Assignment Algorithm ◽  
Placement Algorithm ◽  
Time Invariant

The stabilizing decentralized controller design problem for (possibly descriptor-type) linear time-invariant neutral time-delay systems is considered. A design approach, based on the continuous pole placement algorithm and the decentralized pole assignment algorithm, is proposed. A design example is also presented, to demonstrate the proposed approach.

Robust Controller Design for Descriptor-type Time-delay Systems

2021 ◽  
Vol 20 ◽  
pp. 289-294
Author(s):  
Altug Iftar
Keyword(s):  
Time Delay ◽  
Controller Design ◽  
Linear Time ◽  
Delay Systems ◽  
Time Delay Systems ◽  
Robust Controller ◽  
Frequency Dependent ◽  
Stabilizing Controller ◽  
Linear Time Invariant ◽  
Time Invariant

Linear time-invariant descriptor-type time-delay systems are considered. A robust stabilizing controller design approach for such systems is introduced. Uncertainties both in the time-delays and in other system parameters are considered. A frequency-dependent scalar bound on such uncertainties is first derived. Once this bound is found, the controller design is completely based on the nominal model. However, satisfying a scalar frequency-dependent condition, which uses the derived bound, guarantees robust stability. An example is also presented to illustrate the proposed approach

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