DSP Based Digital Controller for Gun Control System of Armoured Fighting Vehicles 2003-28-0014
Modern armoured fighting vehicles are built with high performance gun and turret laying and stabilization systems, which provide high first round hit probability on the move against stationary and moving targets. The future battlefield scenarios demand much higher performance from the gun and turret stabilization systems of the armoured fighting vehicles to meet future threats. The higher performance of the stabilization system could be ensured only through improved drive components and more complex controller configurations with no degradation in performance over the complete operating temperature range from -55 to +125 degrees Celsius which can be made possible using latest DSP based Digital Controller.
This paper was aimed at discussing the issues related to implementation of DSP based Digital Controller for Weapon Control System of MBT Arjun. Due to articulated flexible structure, dynamic non -linearities and high degree of parameter and model uncertainties the improvement on the accuracy and speed of gun-turret control systems has been limited when compared to aircrafts.
Weapon System of Main Battle Tank Arjun is fitted with Electro Hydraulic Gun Control System. Main features of gun control system are independent stabilization in Azimuth & Elevation and slaving the gun to stabilized sight. Stabilization has been achieved based on Minor loop control strategy.
Minor loop control system technique has been used to design filter structures for effective inertial position control. Existing system works on analog controllers. Current generation Gun control system of Armored fighting vehicles employ Digital controllers for the following advantages like component tolerance being uncritical, component drift having no influence on the system, ease of changing filter characteristics & high reliability.
DSP based Digital controller unit has been developed to replace the existing Analog controller. Digital controller was built around fixed point ADSP - 2181 processor. Bilinear transformation technique was adopted for transformation from analog to digital domain. Cascaded biquad IIR filter algorithm was developed to implement the digital transfer function as biquad implementation reduces numeric errors, can be scaled separately and then cascaded in order to minimize coefficient quantization errors and recursive accumulative errors.
Controller was validated on bench based on frequency response plots and simulation techniques using Matlab - DSP tool box. Dynamic performance tests were carried out on integrating the unit in the tank. Practical problems faced on issues like Zero Order Hold effects, sampling rate, anti aliasing filter order and cut off frequency, resolution of ADC & DAC are discussed in the paper. This paper also includes the features of the developed Digital Controller.