Design Of Missile Guidance Law Considering The Acceleration Restriction

In the military defense system of modern warfare, missile guidance system hasincreasingly important strategic significance. To enable the missile to intercept thetarget accurately, the guidance system need to give reasonable acceleration command toadjust the missile flight trajectory. Overload is the measure of the physical forcesuffered by missile in flight. As the applied load to the component parts of missile canwithstand has to be limited, the overload can’t be too large, so as not to affect thenormal operation of the missile. Under such precondition, this article will designreasonable guidance law for missile guidance system under overload constraint, toensure the missile can be accurately guided.Saturation is a common nonlinear phenomena of control systems. Due to saturation,the increasement of the input of actuator can’t affect the output, resulting in lowersystem dynamic performance. So it’s an important issue for designers to designreasonable controller which can overcome the effects of saturation constraint andimprove the performance. In missile guidance system, missile’s autopilot dynamiccharacteristic is subjected to saturated restriction,which must be taken into account.First of all, the paper reviewed the current status of research of guidance lawmainly including classical and modern navigation guidance law legal, and establishedthe mathematical model of missile-target relative motion and explained the mainprinciple of actuator saturation during missile motion. Then elaborated motionequations of target against missile with the corresponding coordinate.Secondly, according to overload constraint and saturation constraint of missile’sautopilot dynamic characteristics, the paper use command filters and backsteppinginstruction to design two-dimensional plane and three-dimensional space guidance law.In accordance with the principle of local stability, guidance law of line of sight and itsnormal direction will be respectively designed, and the stability of the law will beanalyzed. Then matlab programming will be used to analyze the performance of thedesigned guidance law by simulation,which mainly contains off-target amount and theimpact of the line of sight angular rate, as well as guidance precision of guidance lawfor different target maneuvering, and the effect of actuator saturation limit’s change inthe guidance.Finally, under each of these scenarios, the paper derived two guidance laws ofother forms, in comparison with the performance of the law designed above. It mainlyused augmented proportional navigation law and variable structure guidance law, andtry to find the best solution of missile guidance through comprehensive analysis.