Manoeuvring Target Failure Analysis

Just as in the S.A.S.S system, out of the 5 I.B.M fails only in one engagement did the IMM produce an incorrect behaviour detection. In 2 of the 16 manoeuvring target fails, the IMM produced an incorrect behaviour detection. In the failed engagements where the IMM has not produced an incorrect behaviour detection, then the trajectory optimisation process using the simulated annealing and most probable trajectory approaches are the only possible system failure sources.

A failure by the most probable trajectory component can be excluded as the system will either find or not find a possible target detection based on the up- dated most probable trajectory. It will only update the weapon trajectory if a detection is found.

The reliability analysis of the simulated annealing algorithm performed in Chap- ter 5 would suggest that a failure by this algorithm will have only contributed to a small proportion of the failed intercepts. Assuming that the trajectory op- timisation was successful on each occasion, then the failure will be simply due to the orientation of the seeker scan area to the target. The target will not have been detectable within the area, initially calculated on a distribution of possible trajectories and later on in the engagement a single probable trajectory.

The incorrect behaviour detections will affect the performance of the S.A.M.P.T system in the same manor as the S.A.S.S systems.

The incorrect detection will change the shape of the distribution and associated probabilities. Both the simulated annealing and most probable trajectory systems will then optimise the trajectory on a poor prediction which is far more likely to orientate the seeker scan area away from the target. In the failures where the IMM produced an incorrect detection, the trajectory of the weapon would have been shaped by both processes such that the target would not lie within the scan area. In each of the failed intercepts the S.A.M.P.T had successfully minimised the weapon range to the target to within the seeker detection range. Considering the fails without incorrect detections by the IMM, then this integrated system has been proven to be an effective method for improving the performance of the AAAW against manoeuvring targets.

7.5

Chapter Review

This chapter has the discussed the development and implementation of the third and final integrated fire control system to be discussed in this thesis. An inte- grated fire control system which considers multiple target trajectories initially and then only the most probable trajectory later on in the engagement is proven to be an effective method of improving the performance of the AAAW against manoeuvring targets. This is apparent from a comparison of the number of ma- noeuvring targets intercepted by the AAAW in this system and the F.F. system. However the weapon in this integrated system did not successfully intercept all of the 60 manoeuvring targets generated by the target model.

The potential reasons why the S.A.M.P.T system fails to intercept 2 non ma- noeuvring and a number of manoeuvring targets have been outlined. The results indicate that the hybrid system does not offer a further performance increase over the S.A.S.S system and M.P.T systems.

Chapter 8

Summary and Conclusions

This chapter firstly presents a summary of the research discussed in this thesis. A number of conclusions about the results obtained from the three systems de- veloped are then provided. The thesis then concludes with recommendations for further work.

8.1

Summary

It was demonstrated that the addition of a data link to the AAAW will allow the trajectory of the weapon to be shaped in flight by the transmission of one or more off-boresight commands after the weapon has been launched. Each off- boresight command is comprised of the current weapon heading and a required heading change. The constraints of the original weapon design specified that the absolute sum of the heading changes associated withn transmitted off-boresight commands are limited to 40◦.

It was proposed that the ability to shape the trajectory of the weapon after launch could improve the performance of the AAAW against manoeuvring tar- gets, notably a small agile surface vessel which was representative of a small boat threat.

In order to achieve the maximum performance increase of the AAAW against ma- noeuvring targets, the limited retargeting (trajectory shaping) capability would have to be efficiently utilised over the course of a potential 40s engagement. It was postulated that this could be accomplished through the use of an integrated fire control system which would seek to calculate an optimal shaped weapon tra- jectory. A fundamental component of the integrated fire system would be an integrated tracking and target prediction system.

The tracking system was comprised of a pulsed radar model as the sensor in- put and a Kalman filter based IMM Estimator.

The prediction component calculates the possible trajectories that the target could follow over a maximum 40s weapon flight period. A Markov chain is used to calculate the probability of the target following each predicted trajectory.

The two components were integrated such that as the IMM detected different target behaviours, possible target trajectories could be eliminated. The distri- bution of target trajectories becomes a better prediction of the possible target behaviour as the engagement progresses.

Three integrated fire control systems where developed which, sought to calculate the optimal trajectory considering the distribution of possible target trajectories under different criteria.

In each of the three integrated systems, the AAAW demonstrated a substan- tial performance increase against manoeuvring targets in respect of the initial Fire and Forget system discussed in Chapter 3 of the thesis.