Near-Minimum Time Feedback Controller for Manipulators Using On-Line Time Scaling of Trajectories

1996 ◽  
Vol 118 (2) ◽  
pp. 300-308 ◽  
Author(s):  
A. Kumagai ◽  
D. Kohli ◽  
R. Perez
Keyword(s):  
Feedback Control ◽  
Control Theory ◽  
Open Loop ◽  
Feedback Controller ◽  
Minimum Time ◽  
Control Action ◽  
Time Scaling ◽  
Time Problem ◽  
Time Optimal ◽  
Input Torque

A near-minimum time feedback controller for robotic manipulators with bounded input torques is developed. Since the bang-bang input torque obtained from the timeoptimal control theory leaves little or no room for the extra torque of the feedback control action, it is difficult to combine a minimum time open-loop controller with an additional feedback controller. A simple solution to this problem has been to solve the minimum time problem using arbitrarily reduced torque bounds so that a torque head room is created for the feedback control action. Such a scheme, however, wastes considerable input torque potential and gives significantly larger execution time of the trajectory than the theoretical minimum time calculated from the time-optimal control theory. A stable feedback controller is developed in this paper which applies a time scaling method to move a manipulator in near-minimum time using the allowable input torques efficiently. This new feedback controller algorithm adapts to an uncertain environment and automatically adjusts the desired speed along a specified path to be as fast as possible while avoiding the velocity saturation condition. Numerical examples of the near-minimum time feedback controller are provided using a two-link SCARA manipulator.

scholarly journals Minimum-Time Trajectories for Steered Agent With Constraints on Speed, Lateral Acceleration, and Turning Rate

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
William Lewis Scott ◽  
Naomi Ehrich Leonard
Keyword(s):  
Minimum Principle ◽  
Single Agent ◽  
Open Loop ◽  
Minimum Time ◽  
Lateral Acceleration ◽  
Optimal Controls ◽  
Coverage Problem ◽  
Time Optimal ◽  
Multi Agent ◽  
Heading Angle

We present time-optimal trajectories for a steered agent with constraints on speed, lateral acceleration, and turning rate for the problem of reaching a point on the plane in minimum time with free terminal heading angle. Both open-loop and state-feedback forms of optimal controls are derived through application of Pontryagin's minimum principle. We apply our results for the single agent to solve a multi-agent coverage problem in which each agent has constraints on speed, lateral acceleration, and turning rate.

The Near-Minimum-Time Control Of Open-Loop Articulated Kinematic Chains

1971 ◽  
Vol 93 (3) ◽  
pp. 164-172 ◽  
Author(s):  
M. E. Kahn ◽  
B. Roth
Keyword(s):  
Optimal Control ◽  
Feedback Control ◽  
Response Times ◽  
Equations Of Motion ◽  
Open Loop ◽  
Rigid Bodies ◽  
Minimum Time ◽  
Suboptimal Control ◽  
Dynamical Equations ◽  
Highly Nonlinear

The time-optimal control of a system of rigid bodies connected in series by single-degree-of-freedom joints is studied. The dynamical equations of the system are highly nonlinear, and a closed-form representation of the minimum-time feedback control is not possible. However, a suboptimal feedback control, which provides a close approximation to the optimal control, is developed. The suboptimal control is expressed in terms of switching curves for each of the system controls. These curves are obtained from the linearized equations of motion for the system. Approximations are made for the effects of gravity loads and angular velocity terms in the nonlinear equations of motion. Digital simulation is used to obtain a comparison of response times of the optimal and suboptimal controls. The speed of response of the suboptimal control is found to compare quite favorably with the response speed of the optimal control.

scholarly journals A minimum trapping time problem in optimal control theory

1990 ◽  
Vol 32 (1) ◽  
pp. 100-114 ◽  
Author(s):  
M. E. Fisher ◽  
J. L. Noakes ◽  
K. L. Teo
Keyword(s):  
Optimal Control ◽  
Control Theory ◽  
Optimal Control Theory ◽  
Natural Extension ◽  
Computational Procedure ◽  
Fixed Time ◽  
Minimum Time ◽  
Time Interval ◽  
Trapping Time ◽  
Time Problem

AbstractIn this paper we consider a natural extension of the minimum time problem in optimal control theory which we refer to as the minimum trapping time problem. The minimum trapping time problem requires a fixed time interval [0, T], where T is finite. The aim is to determine a control for which the system trajectory not only reaches a specified target in minimum time but also remains trapped within the target until time T. Our aim is to devise a computational procedure for solving the minimum trapping time problem. The computational procedure we adopt uses control parametrisation in which the class of controls is approximated by a class of piecewise constant functions. The problem we are solving is therefore an approximation to the original minimum trapping time problem. Some properties for the approximate problem are then established. These lead to an extremely efficient iterative procedure for calculating the minimum trapping time.

Tips on Stochastic Optimal Feedback Control and Bayesian Spatiotemporal Models: Applications to Robotics

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Jongeun Choi ◽  
Dejan Milutinović
Keyword(s):  
Sensor Networks ◽  
Feedback Control ◽  
Control Theory ◽  
Mobile Sensor Networks ◽  
Optimal Feedback Control ◽  
Mobile Sensor ◽  
Optimal Feedback ◽  
Spatiotemporal Models ◽  
Feedback Control Theory

This tutorial paper presents the expositions of stochastic optimal feedback control theory and Bayesian spatiotemporal models in the context of robotics applications. The presented material is self-contained so that readers can grasp the most important concepts and acquire knowledge needed to jump-start their research. To facilitate this, we provide a series of educational examples from robotics and mobile sensor networks.

scholarly journals Long-latency reflexes for inter-effector coordination reflect a continuous state feedback controller

2018 ◽  
Vol 120 (5) ◽  
pp. 2466-2483 ◽  
Author(s):  
Frederic Crevecoeur ◽  
Isaac Kurtzer
Keyword(s):  
Feedback Control ◽  
State Feedback ◽  
Feedback Controller ◽  
State Feedback Control ◽  
Comprehensive Treatment ◽  
State Feedback Controller ◽  
Long Latency ◽  
Continuous State ◽  
Long Latency Reflex ◽  
Long Latency Reflexes

Successful performance in many everyday tasks requires compensating unexpected mechanical disturbance to our limbs and body. The long-latency reflex plays an important role in this process because it is the fastest response to integrate sensory information across several effectors, like when linking the elbow and shoulder or the arm and body. Despite the dozens of studies on inter-effector long-latency reflexes, there has not been a comprehensive treatment of how these reveal the basic control organization that sets constraints on any candidate model of neural feedback control such as optimal feedback control. We considered three contrasting ways that controllers can be organized: multiple independent controllers vs. a multiple-input multiple-output (MIMO) controller, a continuous feedback controller vs. an intermittent feedback controller, and a direct MIMO controller vs. a state feedback controller. Following a primer on control theory and review of the relevant evidence, we conclude that continuous state feedback control best describes the organization of inter-effector coordination by the long-latency reflex.

MR thermometry-based feedback control of efficacy and safety in minimum-time thermal therapies: Phantom andin-vivoevaluations

2006 ◽  
Vol 22 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Dhiraj Arora ◽  
Daniel Cooley ◽  
Trent Perry ◽  
Junyu Guo ◽  
Andrew Richardson ◽  
...  
Keyword(s):  
Feedback Control ◽  
Minimum Time ◽  
Efficacy And Safety ◽  
Mr Thermometry ◽  
Thermal Therapies
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