Time-delayed Control Algorithm Research Articles

Experimental investigation of an active mass damper system with time delay control algorithm

This paper experimentally investigates the effectiveness and applicability of the time delay control (TDC) algorithm, which is simple and robust to unknown system dynamics and disturbance, for an active mass damper (AMD) system to mitigate the excessive vibration of a building structure. To this end, the theoretical background including the mathematical formulation of the control system is first described; and then, a thorough experimental study using a shaking table system with a small-scale three-story building structural model is conducted. In the experimental tests, the performance of the proposed control system is examined by comparing its structural responses with those of the uncontrolled system in the free vibration and forced vibration cases. It is clearly verified from the test results that the TDC algorithm embedded AMD system can effectively reduce the structural response of the building structure.

Active mass damper system using time delay control algorithm for building structure with unknown dynamics

This paper numerically investigates the feasibility of an active mass damper (AMD) system using the time delay control (TDC) algorithm, which is one of the robust and adaptive control algorithms, for effectively suppressing the excessive vibration of a building structure under wind loading. Because of its several attractive features such as the simplicity and the excellent robustness to unknown system dynamics and disturbance, the TDC algorithm has the potential to be an effective control system for mitigating the vibration of civil engineering structures such as buildings and bridges. However, it has not been used for structural response reduction yet. In this study, therefore, the active control method combining an AMD system with the TDC algorithm is first proposed in order to reduce the wind-induced vibration of a building structure and its effectiveness is numerically examined. To this end, its stability analysis is first performed; and then, a series of numerical simulations are conducted. It is demonstrated that the proposed active structural control system can effectively reduce the acceleration response of the building structure.

Design and experimental implementation of time delay control for air supply in a polymer electrolyte membrane fuel cell system

This paper studies the air flow control for preventing the starvation and/or obtaining the maximum net power of a Polymer Electrolyte Membrane (PEM) fuel cell system using time delay control (TDC). Feedforward and feedback controls are utilized simultaneously to prevent air shortage during the transient response of the fuel cell operation. The TDC algorithm design is created with a low-order dynamic model, and its superior performances are proven using a real-time control experiment. The optimal air excess ratio is calculated experimentally given the variation of the external load, and the net power increase is discussed by comparison with the results obtained from fixed air excess ratio. The Ballard 1.2 kW PEM fuel cell system is used for the experiments as a test rig, and the LabView system is used for the real-time air flow control. The superiority of the TDC performance is proven by comparison with other control algorithms such as the proportional–integral control (PIC), feedforward control, and the original manufacturer's control. The proposed control algorithm can improve PEM fuel cell system performance by preventing air shortage and/or by obtaining higher performance.

Design and control of a nanoprecision XYΘ scanner

This paper describes the design and control of a nanoprecision XY Theta scanner consisting of voice coil motors and air bearing guides. The proposed scanner can be installed on a conventional XY stage with long strokes to improve the positioning accuracy and settling performance. Major design considerations in developing a high precision scanner are sensor accuracy, actuator properties, structural stability, guide friction, and thermal expansion. Considering these factors, the proposed scanner is made of invar, which has a small thermal expansion coefficient and good structural stiffness. Four voice coil motors drive the scanner, which is suspended by four air bearing pads, in the x, y, and theta directions. The scanner's position is measured by three laser interferometers which decouple the scanner from the conventional stage. The mirror blocks reflecting the laser beams are fixed using viscoelastic sheets, ensuring that the scanner has a well-damped structural mode. A time delay control algorithm is implemented on the real-time controller to control the scanner. The effectiveness of the proposed scanner is verified experimentally.

다관절 휴머노이드 로봇 팔의 제어를 위한 시간지연 제어기의 FPGA 구현 및 실험

In this paper, a time-delayed controller for position control of humanoid robot arms is designed and implemented on a field programmable gate array(FPGA) chip. The time-delayed control algorithm is simple to implement, and robust to reject disturbances. The time-delayed control method uses the one sample time-delayed previous information to cancel out uncertainties in the system. Since the sampling time is so fast with the current hardware technology, the time-delayed controller can be implemented. However, inertia values should be correctly estimated to have the better performance. The position tracking tasks of humanoid robot arms are tested to compare performances of several control algorithms including the time-delayed controller.

Autotuning positive feedback time delay controller for dead time processes

Biased relay feedback tests are applied to dead time processes to obtain their ultimate gains and ultimate frequencies. First-order process with dead time models are then fitted to the estimated gains and frequencies. A time delay controller that incorporates a simple compensator with a delay element in positive feedback can be derived from the fitted model. The time delay controller gives better performance comparing with classical Ziegler and Nichols tuned PID controller. Experimental study is included to demonstrate the effectiveness of the proposed tuning scheme and the time delay control algorithm.

A time-delay control algorithm for an industrial electric heater

This paper discusses stabilizing control for discrete systems with a time delay in the state variables. The control algorithms are based on the Lyapunov stability theory. For an industrial electric heater, a time-delay discrete model is identified using a recursive least squares technique, and real-time control via the proposed control algorithm to the heater is performed. The performance of the industrial application shows that the temperature variation in the heater is within ± 1.5°C (0.5%), and the system has good load change rejection and shorter recovery time.