Disturbance Suppression Ability Research Articles

Combining a Disturbance Observer with Triple-Loop Control Based on MEMS Accelerometers for Line-of-Sight Stabilization.

In the CCD-based fine tracking optical system (FTOS), the whole disturbance suppression ability (DSA) is the product of the inner loop and outer position loop. Traditionally, high sampling fiber-optic gyroscopes (FOGs) are added to the platform to stabilize the line-of-sight (LOS). However, because of the FOGs’ high cost and relatively big volume relative to the back narrow space of small rotating mirrors, we attempt in this work to utilize a cheaper and smaller micro-electro-mechanical system (MEMS) accelerometer to build the inner loop, replacing the FOG. Unfortunately, since accelerometers are susceptible to the low-frequency noise, according to the classical way of using accelerometers, the crucial low-frequency DSA of the system is insufficient. To solve this problem, in this paper, we propose an approach based on MEMS accelerometers combining disturbance observer (DOB) with triple-loop control (TLC) in which the composite velocity loop is built by acceleration integration and corrected by CCD. The DOB is firstly used to reform the platform, greatly improving the medium-frequency DSA. Then the composite velocity loop exchanges a part of medium-frequency performance for the low-frequency DSA. A detailed analysis and experiments verify the proposed method has a better DSA than the traditional way and could totally substitute FOG in the LOS stabilization.

High-acceleration and high-precision point-to-point motion control based on disturbance observer with improved Q-filter

Under conditions of high acceleration, high-precision and fast positioning of point-to-point motions with short strokes is restricted by the internal and external disturbances occurring in the motion process. To address this issue, a disturbance observer-based control scheme is employed here to suppress the disturbances, which combines a feedforward controller and a feedback controller. Since the low-pass filter of disturbance observer (Q-filter) determines the disturbance suppression ability after the nominal model has been identified, the Q-filter design becomes the most important consideration in practical control. In this article, an improved Q-filter is proposed to further suppress the disturbances by canceling the resonance peak of the binomial filter. High-acceleration point-to-point motions are conducted on a linear-driving stage and the experimental results demonstrate that the proposed control scheme is capable of achieving high-precision and fast positioning control. Since the improved Q-filter exhibits superior disturbance suppression ability, the positioning time with positioning error of 2 µm has been shortened from 13.1 to 11.4 ms.

Study on Predictive Control Technology Based on Disturbance of Electrically Heated Boiler

Electrically heated boiler is a large inertia, time invariant and nonlinear process. Classical PID control algorithm cannot make the system meet up the needs of performance index. Dynamic matrix control (DMC) predictive control algorithm is adopted to control electrically heated boiler temperature. Simulation result shows that the temperature control system’s overshoot is zero, settling time is 200s, the steady-state error is 9.7574e-006. Compared with PID control, DMC predictive control decreases the overshoot and settling time and improves the system dynamic performance. Aim at disturbance, improved DMC control algorithm is put forward and enhance the system disturbance suppression ability.