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دانلود رایکان مقاله انگلیسی ISI با موضوع حلقه پایاسازی سیستم طوقه دو محوره با استفاده از کنترلر فازی نوع PID خود تنظیم شونده

عنوان فارسی مقاله:

حلقه پایاسازی سیستم طوقه دو محوره با استفاده از کنترلر فازی نوع PID خود تنظیم شونده

عنوان انگلیسی مقاله:

Stabilization loop of a two axes gimbal system using self-tuning PID type fuzzy controller

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2. Problem formulation

The stabilization is usually provided to the sensor by suspending it on the inner gimbal of two axes gimbal system as shown in Fig. 1 [26]. A rate gyro located on the inner gimbal is utilized to measure the angular rates in the two planes of interest. The gyro outputs are used as feedback to torque motors related to the gimbals to provide boresight error tracking and stabilization against base angular motion. The overall control system is constructed utilizing two identical stabilization loops (Fig. 2) for the inner (elevation) and outer (azimuth) gimbals. The control system of two axes gimbal system attempts to align the sensor optical axis in elevation and azimuth planes with a line joining the sensor and target which is called the line of sight (LOS) so that the sensor optical axis is kept nonrotating in an inertial space despite torque disturbances which affect the elevation and azimuth gimbals and basically caused by the base angular motions which are usually imposed by the operating environment. Therefore, the stabilization loop must isolate the sensor from the angular base motion and disturbances that disturb the aim-point, i.e. the output rates of stabilization loops must follow certain input rate commands so that the rate error is made zero. According to Newton's first and second laws, all that is required to prevent an object (sensor) from rotating with respect to inertial space is to ensure that the applied torque is zero [27]. However, even in well designed and careful electromechanical systems, the operating environment creates numerous sources of torque disturbances that affect on a real mechanism making extreme motion or jitter of line of sight [27]. In such environments, as all control systems, the gimbal control system suffers from problems related to undesirable overshoot, longer settling times and vibrations, and stability. In order to overcome these problems, the gimbal system control loops will be developed using adaptive PID-type fuzzy controller. The elevation and azimuth control loops are related by the cross coupling unit which is built based on the relationships of torques affect the gimbals. The cross coupling express the properties of the gimbal system dynamics and reflects the fact that azimuth gimbal can affect on elevation gimbal even when base body is nonrotating. Also, there is similar impact from elevation gimbal on azimuth gimbal. As a result, the cross coupling is defined as the effect on one axis by the rotation of another [6]. In this paper, the model of two axes gimbal system is obtained and simulated considering the dynamic mass unbalance which is the result of a non-symmetrical mass distribution called Product of Inertia (POI) [6]. The dynamic mass unbalance concept can be indicated by the inertia matrix. If the gimbal has a symmetrical mass distribution with respect to its frame axes, so the gimbal has no dynamic mass unbalance and its inertia matrix is diagonal and vice versa.