<title>Hardware-in-the-loop simulation by use of computer-generated images</title>

In recent years computer performance has been improving so rapidly that hardware-in-the-loop simulation by using computer generated images (CGI-HWIL simulation) has come to play the great role in developing and evaluating many kinds of imaging missile systems. Generally speaking, there are two principle methods in CGI-HWIL simulation. One is a method using scene projector for in-band seeker under test, and the other is a method injecting image directly into missile signal processing unit beyond seeker sensor. In Japan, the latter is generally used as an effective method of CGI-HWIL simulation to develop and evaluate missile systems. That is because the former can do nothing but depend on import for the scene projector, so there are a lot of disadvantageous points in respects of cost and maintenance. In our company, the former composed by low cost commercial off-the-shelf (COTS) scene generator also has been used to research image homing missile systems. There are two special features in the CGI-HWIL simulation method. One is how to emulate the seeker optics and electronics characteristics, and the other is the technique how to compensate the system latency caused by scene generation components. These special techniques allow us to keep the stability of seeker tracking loop, and to achieve real-time CGI-HWIL simulation effectively with low cost scene generator. First of all, the outline of the CGI-HWIL simulation method is shown. Next, problem in real-time simulation is described, and at the end how the problem is solved to achieve real-time simulation is explained.