Variable structure control of a tank gun

Variable structure control (VSC), which provides immunity to plant parameter changes when the system is in the sliding mode, is applied to the position control of a tank gun with its large uncertainties. The VSC design is based on a second-order linear time-invariant plant with bounded uncertain parameters. This is a huge reduction of an elaborate nonlinear model of the tank´s turret and gun system. Two VSC strategies were designed and tested: one, with a linear switching line, termed the conventional VSC (CVSC), and the second, in which the entire state trajectory is a sliding curve, termed the modified VSC (MVSC). The CVSC was tested by simulation on a full model as well as on a stationary tank; the MVSC, which is a more complex control law, was tested by simulation only. Both designs showed excellent robustness. The chattering did not excite high-frequency modes, but it caused a large energy drain