Proportional control

About: Proportional control is a research topic. Over the lifetime, 3756 publications have been published within this topic receiving 49050 citations.

A two-layered fuzzy logic controller for proportional hydraulic system

Abstract: Existing fuzzy control methods do not perform well when applied to proportional hydraulic systems (PHS) containing nonlinearities arising from unknown deadzones. In this paper, a two-layered fuzzy logic controller is proposed for controlling a PHS with deadzones. The two-layered control structure consists of a fuzzy logic-based precompensator followed by a usual fuzzy PD controller. This system was implemented for PHS position control. The results show that a two-layered fuzzy logic controller has superior performance compared to usual fuzzy PD controller. In addition, the proposed scheme is robust to disturbance.

Model-based trajectory tracking control for an electrohydraulic lifting system with valve compensation strategy

Abstract: The natural frequency of the electrohydraulic system in mobile machinery is always very low, which brings difficulties to the controller design. To improve the tracking performance of the hydraulic system, mathematical modeling of the electrohydraulic lifting system and the rubber hose was accomplished according to an electrohydraulic lifting test rig built in the laboratory. Then, valve compensation strategy, including spool opening compensation (SOC) and dead zone compensation (DZC), was designed based on the flow-pressure characteristic of a closed-centered proportional valve. Comparative experiments on point-to-point trajectory tracking between a proportional controller with the proposed compensations and a traditional PI controller were conducted. Experiment results show that the maximal absolute values of the tracking error are reduced from 0.039 m to 0.019 m for the slow point-to-point motion trajectory and from 0.085 m to 0.054 m for the fast point-to-point motion trajectory with the proposed compensations. Moreover, tracking error of the proposed controller was analyzed and corresponding suggestions to reduce the tracking error were put forward.

Application of a Proportional Feedback Controller for Active Control of a Vibration Isolator

Abstract: This paper proposes the application of a proportional controller to active vibration control incorporated with a passive vibration isolator to suppress its resonant oscillation at its natural frequency. Vibration acceleration acquired from an accelerometer is fed to the controller as a feedback signal. The processed signal from the controller is transmitted to the voice coil actuator in order to control the vibration. Firstly, based on the theoretical equations which govern the vibrational system, the physical mechanism of active control in the total system is studied. Then, vibration on a stiff foundation and passive isolator is measured in order to understand the efficiency of the traditional vibration control method. Finally, an experiment on active vibration control is performed to study the suppression efficiency of the oscillation of the passive vibration isolator. The experiment results show that 99% of the vibration energy can be cancelled by active control.

Active suppression of finite-amplitude Rayleigh–Bénard convection

Abstract: We study by a fully nonlinear three-dimensional pseudospectral time-splitting simulation, the feedback control of a layer of fluid heated from below. The initial condition corresponds to a steady large-amplitude preferred convection state obtained at Prandtl number of 7.0 and Rayleigh number of 104, which is about six times the Rayleigh critical value. A robust controller based on the LQG (linear–quadratic–Gaussian) synthesis method is used. Both sensors and actuator are thermal-based, planar, andassumed to be continuously distributed. The simulated results show that large-amplitude steady-state convection rolls can be suppressed by the linear LQG controller action. The Green's function of the controller gives the shape of the control action corresponding to a point measurement. In addition, for Rayleigh numbers below the proportional feedback control stability limit, this controller appeared to be effective in damping out steady-state convection rolls as well. However, in a region very near the proportional control stability limit, proportional control action induces subcritical g-type hexagonal convection, which is obtained here through direct simulations. Note that well above this proportional control limit, the LQG still damps out all convection. The nonlinear plant model is validated by comparing check cases with published results.

Neural-tuned PID controller for Point-to-point (PTP) positioning system: Model reference approach

Abstract: Point-to-Point (PTP) motion control systems play an important role in industrial engineering applications such as advanced manufacturing systems, semiconductor manufacturing systems and robot systems. Until know, PID(proportional-integral-derivative) controllers are still the most popular controller used in industrial control systems including PTP motion control systems due to their simplicity and also satisfactory performances. However, since the PID controller is developed based on the linear control theory, the controller gives inconsistent performance for different condition due to system nonlinearities. In order to overcome this problem, Neural-tuned PID control using model reference adaptive control (MRAC) is proposed. By using EMRAN (Extended Minimal Resource Allocation Algorithm) to train the Radial Basis Funciton (RBF) Network, the PID controller can learn, adapt and change its parameters based on the condition of the controlled-objectin real-time. The effectiveness of the proposed method is evaluated experimentally in real time using an experimental rotary positioning system. The experimental results show that the proposed system is better than classical PID controller in terms of not only positioning performance but also robustness to inertia variations.