Discrete optimal control for robot manipulators

2013 ◽  
Vol 33 (1/2) ◽  
pp. 423-444 ◽  
Author(s):  
Mohammad Mehdi Fateh ◽  
Maryam Baluchzadeh
Keyword(s):  
Optimal Control ◽  
Control Strategy ◽  
Optimal Algorithm ◽  
Robot Manipulators ◽  
Torque Control ◽  
Linear Quadratic ◽  
Voltage Control Strategy ◽  
Content Type ◽  
Discrete Optimal Control ◽  
Electrically Driven Robot

Purpose – Applying discrete linear optimal control to robot manipulators faces two challenging problems, namely nonlinearity and uncertainty. This paper aims to overcome nonlinearity and uncertainty to design the discrete optimal control for electrically driven robot manipulators. Design/methodology/approach – Two novel discrete optimal control approaches are presented. In the first approach, a control-oriented model is applied for the discrete linear quadratic control while modeling error is estimated and compensated by a robust time-delay controller. Instead of the torque control strategy, the voltage control strategy is used for obtaining an optimal control that is free from the manipulator dynamics. In the second approach, a discrete optimal controller is designed by using a particle swarm optimization algorithm. Findings – The first controller can overcome uncertainties, guarantee stability and provide a good tracking performance by using an online optimal algorithm whereas the second controller is an off-line optimal algorithm. The first control approach is verified by stability analysis. A comparison through simulations on a three-link electrically driven robot manipulator shows superiority of the first approach over the second approach. Another comparison shows that the first approach is superior to a bounded torque control approach in the presence of uncertainties. Originality/value – The originality of this paper is to present two novel optimal control approaches for tracking control of electrically driven robot manipulators with considering the actuator dynamics. The novelty is that the proposed control approaches are free from the robot's model by using the voltage control strategy. The first approach is a novel discrete linear quadratic control design supported by a time-delay uncertainty compensator. The second approach is an off-line optimal design by using the particle swarm optimization.

Multi-level nursing workforce planning considering talent management in healthcare with a dynamic quantitative approach

Kybernetes ◽  
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shila Monazam Ebrahimpour ◽  
Fariborz Rahimnia ◽  
Alireza Pooya ◽  
Morteza Pakdaman
Keyword(s):  
Optimal Control ◽  
Dynamic Model ◽  
Health Sector ◽  
Workforce Planning ◽  
Talent Management ◽  
Optimal Number ◽  
Linear Quadratic ◽  
Planning Period ◽  
Linear Quadratic Optimal Control ◽  
Content Type

PurposeWorkforce planning must answer how many workforces, in which positions, and talents, and when each organization is needed. To find the requirements workforce, organizations need to know the organizational position and talents pools. Clarifying the number of workforces required in each pool requires attention to workforce flows, including hiring, promotion, degradation, horizontal movement, and exiting the organization. It is a dynamic issue and must be addressed over several periods over a specific duration, which adds to the complexity. According to the talent management presented in this research, all the above complex questions are answered by applying the optimal control (OC) model according to talent management presented in this research.Design/methodology/approachThis research presents a dynamic model by using a linear-quadratic optimal control model, which was solved by Pontryagin's maximum principle, to achieve an optimal number of workforce requirements for each of the positions of nursing services manager, supervisor, head nurses and nurses in the health sector according to the required talents in each position.FindingsThe results have shown that the target value of workforce numbers has been achieved in the planning period, and the validation test and sensitivity analysis justified the model by reaching the workforce planning targets.Originality/valueThis study provides a dynamic model for achieving quantitative workforce planning targets; the model presented in this manuscript has included an important qualitative factor, namely workforce talents. According to the authors' review, there is no comprehensive research devoted to workforce planning through optimal control models by attention to workforces skills.

Optimal vaccination policy and cost analysis for epidemic control in resource-limited settings

Kybernetes ◽  
2015 ◽  
Vol 44 (3) ◽  
pp. 475-486 ◽  
Author(s):  
Kuan Yang ◽  
Ermei Wang ◽  
Yinggao Zhou ◽  
Kai Zhou
Keyword(s):  
Optimal Control ◽  
Control Strategy ◽  
Mass Action ◽  
Sir Epidemic Model ◽  
Epidemic Control ◽  
Optimal Control Strategy ◽  
Content Type ◽  
Total Cost ◽  
Time Optimal ◽  
The Impact

Purpose – The purpose of this paper is to use analytical method and optimization tools to suggest time-optimal vaccination program for a basic SIR epidemic model with mass action contact rate when supply is limited. Design/methodology/approach – The Lagrange Multiplier Method and Pontryagin’s Maximum Principle are used to explore optimal control strategy and obtain analytical solution for the control system to minimize the total cost of disease with boundary constraint. The numerical simulation is done with Matlab using the sequential linear programming method to illustrate the impact of parameters. Findings – The result highlighted that the optimal control strategy is Bang-Bang control – to vaccinate with maximal effort until either all of the resources are used up or epidemic is over, and the optimal strategies and total cost of vaccination are usually dependent on whether there is any constraint of resource, however, the optimal strategy is independent on the relative cost of vaccination when the supply is limited. Practical implications – The research indicate a practical view that the enhancement of daily vaccination rate is critical to make effective initiatives to prevent epidemic from out breaking and reduce the costs of control. Originality/value – The analysis of the time-optimal application of outbreak control is of clear practical value and the introducing of resource constraint in epidemic control is of realistic sense, these are beneficial for epidemiologists and public health officials.

Examination of Different Control Strategies of Heavy-Vehicle Performance

1996 ◽  
Vol 118 (3) ◽  
pp. 489-498 ◽  
Author(s):  
L. Palkovics ◽  
M. El-Gindy
Keyword(s):  
Control Strategy ◽  
Control Strategies ◽  
Linear Quadratic Regulator ◽  
Torque Control ◽  
Heavy Vehicle ◽  
Vehicle Model ◽  
Linear Quadratic ◽  
Vehicle Performance ◽  
Active Steering ◽  
Handling Characteristics

Heavy vehicles play an economically important role in the transportation process, and their numbers have been increasing for several decades. The active safety of the highway system is an important consideration in the design of a heavy vehicle combination. In this paper, the handling characteristics of a 5-axle tractor-semitrailer is examined and used to test for the desired features of the vehicle’s handling and stability. Using these results the optimal control criterion is derived for the vehicle. Four different control strategies are examined by using the Linear Quadratic Regulator (LQR) approach. These are, active steering of the rear wheels of the tractor; active steering of the wheels of the trailer; active torque control in the fifth-wheel joint; and active yaw torque acting on the tractor. These controllers are designed and examined using a simplified linear vehicle model. In addition to discussing the above-mentioned approaches, this paper discusses a method of modifying the slip angles at the tractor’s rear (driven) axles, however the yaw torque at the tractor cg also can be controlled using what is called “unilateral braking.” As well, the replacement of the active torque control at the fifth wheel joint, by a control strategy based on the usage of controllable dampers at the fifth-wheel joint, will also be examined. In this case, a nonlinear mathematical model of the vehicle is used and a modified control strategy called the RLQR/H∞ approach is used to ensure the vehicle’s performance in the presence of parametric uncertainties. The examination of these control strategies is conducted by using a sophisticated non-linear vehicle model, and the influence of these control strategies on the vehicle’s directional and roll stability during severe path-follow lane-change manoeuvre is discussed.

Research of the Inverted Pendulum System Based on the Linear Quadratic Optimal Control

2014 ◽  
Vol 568-570 ◽  
pp. 1104-1107
Author(s):  
Shu Fen Qi ◽  
Huan Huan Liu ◽  
Hong Tao Tian
Keyword(s):  
Optimal Control ◽  
Control Strategy ◽  
Inverted Pendulum ◽  
Balance Control ◽  
Single Stage ◽  
Linear Quadratic ◽  
Linear Quadratic Optimal Control ◽  
Pendulum System ◽  
Inverted Pendulum System ◽  
Quadratic Optimal Control

As an ideal experimental method in the study of control theory, inverted pendulum system is an indispensable tool to examine the effects of control strategy. In this paper the corresponding mathematical model and the state space equation are established according to studying the working principle and balance control problem of the single stage linear inverted pendulum system. Using MATLAB solves them and gets the consequences. Finally, the linear quadratic optimal control strategy is used to design the controller of single-stage inverted pendulum system, and a simulation study is carried out. The simulation results show the effectiveness of the most sorrow regulator of the quadratic. And basic rule can be found out between the dynamic response of the inverted pendulum system and weighting matricesandin the LQR.

Thermal Management of Single- and Dual-Tank Fuel-Flow Topologies Using an Optimal Control Strategy

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
P. G. Huang ◽  
D. B. Doman
Keyword(s):  
Heat Transfer ◽  
Optimal Control ◽  
Control Strategy ◽  
Linear Quadratic Regulator ◽  
Operating Conditions ◽  
Adjoint Equations ◽  
Linear Quadratic ◽  
Optimal Control Strategy ◽  
Flow Topology ◽  
Operation Conditions

The effect of fuel topology and control on thermal endurance of aircraft using fuel as a heat transfer agent was studied using an optimal dynamic solver (OPT). The dynamic optimal solutions of the differential equations governing the heat transfer of recirculated fuel flows for single- and dual-tank arrangements were obtained. The method can handle sudden jumps of operating conditions across different operating zones during mission and/or situations when control parameters have reached their physical limits. Although this method is robust in providing an optimal control strategy to prolong thermal endurance of aircrafts, it is not ideal for practical application because the method required iterative procedures to solve expensive nonlinear equations. The linear quadratic regulator (LQR), the feedback controller, can be derived by linearizing the adjoint equations at trim points to offer a simple control strategy, which can then be implemented directly in the feedback control hardware. The solutions obtained from both OPT and LQR were compared, and it was found two solutions were almost identical except in regions having sudden jump of operation conditions. Finally, a comparison between single- and dual-tank arrangements was made to demonstrate the importance of the flow topology. The study shows the dual-tank arrangement allows flexibility in how energy is managed and can release energy faster than a single-tank topology and hence provides improved aircraft thermal endurance.

Infinite-time linear–quadratic optimal control of the BLDC motor exploiting a nonlinear finite element model

2017 ◽  
Vol 36 (3) ◽  
pp. 633-648
Author(s):  
Jakub Bernat ◽  
Slawomir Jan Stepien ◽  
Artur Stranz ◽  
Paulina Superczynska
Keyword(s):  
Finite Element ◽  
Control Strategy ◽  
Element Model ◽  
Nonlinear Finite Element ◽  
Control Technique ◽  
Bldc Motor ◽  
Linear Quadratic ◽  
Infinite Time ◽  
Content Type ◽  
Nonlinear Finite Element Model

Purpose This paper aims to present a nonlinear finite element model (FEM) of the Brushless DC (BLDC) motor and the application of the optimal linear–quadratic control-based method to determine the excitation voltage and current waveform considering the minimization of the energy injected to the input circuit and energy lost. The control problem is designed and analyzed using the feedback gain strategy for the infinite time horizon problem. Design/methodology/approach The method exploits the distributed parameters, nonlinear FEM of the device. First, dynamic equations of the BLDC motor are transformed into a suitable form that makes an ARE (algebraic Riccati equation)-based control technique applicable. Moreover, in the controller design, a Bryson scaling method is used to obtain desirable properties of the closed-loop system. The numerical techniques for solving ARE with the gradient damping factor are proposed and described. Results for applied control strategy are obtained by simulations and compared with measurement. Findings The proposed control technique can ensure optimal dynamic response, small steady-state error and energy saving. The effectiveness of the proposed control strategy is verified via numerical simulation and experiment. Originality/value The authors introduced an innovative approach to the well-known control methodology and settled their research in the newest literature coverage for this issue.

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