Open-loop controller

About: Open-loop controller is a research topic. Over the lifetime, 16148 publications have been published within this topic receiving 224014 citations. The topic is also known as: non-feedback controller & open-loop control law.

On force-tracking impedance control of robot manipulators

Abstract: A reference force-tracking impedance control system is proposed, consisting of a conventional impedance controller in the inner-loop and a trajectory modifying controller in the outer-loop for force-tracking. The design of the outer-loop is presented and the stability of the two-loop control system is analyzed. A computationally efficient control algorithm for the inner-loop is suggested. Simulation results are presented. The controller is able to achieve excellent position and force-tracking with unknown environment stiffness and the presence of a burr on the tracking surface. >

Design and simulation of extremum-seeking open-loop optimal control of current profile in the DIII-D tokamak

Abstract: In a magnetic fusion reactor, the achievement of a certain type of plasma current profiles, which are compatible with magnetohydrodynamic stability at high plasma pressure, is key to enable high fusion gain and non-inductive sustainment of the plasma current for steady-state operation. The approach taken toward establishing such plasma current profiles at the DIII-D tokamak is to create the desired profile during the plasma current ramp-up and early flattop phases. The evolution in time of the current profile is related to the evolution of the poloidal flux, which is modeled in normalized cylindrical coordinates using a partial differential equation usually referred to as the magnetic diffusion equation. The control problem is formulated as an open-loop, finite-time, optimal control problem for a nonlinear distributed parameter system, and is approached using extremum seeking. Simulation results, which demonstrate the accuracy of the considered model and the efficiency of the proposed controller, are presented.

Design of Clutch-Slip Controller for Automatic Transmission Using Backstepping

Abstract: To improve the shift quality of vehicles with clutch-to-clutch gearshifts, a nonlinear controller using backstepping technique is designed for the clutch-slip control. Model uncertainties including steady-state errors and unmodeled dynamics are also considered as additive disturbance inputs, and the controller is designed such that the error dynamics is input-to-state stable. Lookup tables, which are widely used to represent complex nonlinear characteristics of engine systems, appear in their original form in the designed nonlinear controller. Finally, the designed controller is tested on an AMESim power train simulation model. Comparisons with an existing linear algorithm are given as well.

Fast and robust voltage control of DC–DC boost converter by using fast terminal sliding mode controller

Abstract: In this study, a fast terminal sliding-mode control scheme is proposed as a new approach for the voltage tracking control of the DC-DC boost converter affected by disturbances, such as the variations in the input voltage and the load resistance. Some experiments are performed on a test bench to show the effectiveness of the proposed approach. The fast reference tracking capability with small overshoot and robustness to the disturbances of the designed controller is verified by the experimental results. Moreover, the results demonstrate that the proposed controller has a better performance related to conventional sliding mode and proportional-integral controllers in terms of the settling time and robustness to the disturbances.

Sequential design of hysteresis current controller for three-phase inverter

Abstract: In this paper, a novel multivariable hysteresis current controller for three-phase inverters is presented. Hysteresis controllers are intrinsically robust to system parameters, exhibit very high dynamics, and are suitable for simple implementation. The main drawback of the hysteresis controller is a limited control on transistors' switching frequency. Very high switching frequency may result if three independent controllers are used. Multivariable solutions were proposed in the literature to solve the problem. In this paper, it is shown how the use of a sequential design for the multivariable controller can further contribute to transistors' switching frequency reduction, with no significant increase in the hardware implementation complexity. The proposed controller is illustrated and compared with other hysteresis controllers presented in the literature. It ensures a significant reduction of transistors' switching frequency with respect to the other tested controllers, under the same operating conditions. A prototype controller is also presented. The effects of noise captured by current sensors (especially Hall-effect type) on the performance of industrial hysteresis controllers are discussed. It is shown how the sequential design of the controller can also help in solving this critical problem. Experimental results are reported to confirm the quality of the proposed controller. The system stability condition is derived in an appendix.