Nonlinearity Problem Analysis of Target Tracking Based on Rotational Double Prisms

For target tracking based on rotational double prisms, the relation between beam steering and prism rotation is nonlinear. Based on the two groups of inverse solutions of prism orientations derived using the two-step method, the directional derivative in the moving direction of the target is calculated to derive the ratio of the rotational speed of the prisms to the slewing rate of beams, which is used to discuss the requirements of tracking targets with different orientations in different moving directions for driving and controlling over prism rotation. It is found that for a given system, the requirements depend only on the deflection angle of the present target orientation and the angle between the target moving direction and the radial direction. The tangential and radial movement of the target may result in control singularity for prism rotation on the inner and outer edges of the field of regard, respectively. The requirements of target tracking for driving and controlling over the rotation of the two prisms are slightly different. There are minor differences in the analysis results based on the two groups of inverse solutions.