Investigation On Design Of Homing Missile Strapdown Guidance System Based On Proportional Navigation Laws

Missile guidance system plays an important role in missile performance, which provide position information to guidance missile fly to target. A great deal of tactical missiles has used homing guidance system with inertial stabilitization equipment, namely Seeker is located on a set of stabilized platform, antenna can rotate relative to axis of missile body. One of development trend of missiles in the future is the application of strapdown seeker, namely the seeker is fixed on missile body directly, measure orientation is identical with that of missile body. The strapdown seeker has advantage of high-reliability and low manufacturing cost. However, the strapdown seeker can only measure the angle between line-of-sight and missile body axis, which can not satisfy requirement of proportional navigation. As a consequence, other information is required to eliminate the effect of missile attitude. On the condition of seeker measure is inaccurate, performance of guidance system is worse even unstable. In the case of second-order linear seeker, on the condition of incomplete compensation system stability is study in this paper. A simple method for improving stability is suggested.The main content in this paper include:1. Two kind of acceleration autopilot in lateral loop are studied. One is composed of rate gyroscope and accelerometer, the other is composed of two accelerometers. The transfer function of autopilot is get.2. Proportional navigation law is proposed. Trajectory equation on the condition of N = 2 is deduced, the qualification of linear trajectory in attack plane is get and the variation of acceleration is analyzed. Finally, impact of initial value of line-of-sight and navigation constant on the attack trajectory is summarized by trajectory simulation.3. The method of adding missile body attitude compensation to strapdown guidance system to realize proportional navigation is introduced and the condition to stable system is deduced. Next, cascading a first-order delay to improve system stabilization is suggested. Lastly a proper delay time constant is selected and the simulation result of strapdown guidance system is given. By analyzing simulation result, on the conditions of seeker measure isinaccurate adding a time-delay in forward channel can reduce the effect of missilebody attitude and improve system performance. The conclusion in this paper ishelp to the design of strapdown guidance system.