Rocket Trajectory Correction Using Pulsers Mechanism and a GPS Receiver for Roll Rate & Angle Estimation

Assaf Malul, Tzafrir Keynan and Danny Newman

Abstract:	This paper presents an overview and achievements of the TechRoll project: A 160mm, mid-range trajectory corrected rocket. The project was developed by BAE Systems Rokar Int. and IMI (Israeli Military Industries) Givon Rocket division, The tested platform was a 160mm mid range artillery rocket, which was roll -stabilized at 13 Hz (at maximum point). A major requirement for the modern military arena is to achieve an accurate hit of a distinct target and to reduce miss hits in order to minimize collateral damages (civilian or friendly sites). Yet, sophisticated missiles are expensive and require a sophisticated and expensive lunching system. Unguided rockets provide a widely available and inexpensive weapon, although one having a greatly dispersed point of impact. E.g., the CEP of the point of impact is roughly 2 % of the range of an artillery rocket. Currently there is a growing demand to dramatically increase the precision of artillery rockets while maintaining low cost. The goal was achieved by integrating an inexpensive system of sensors for trajectory determination with an inexpensive path correction system. Rokar and IMI conducted ground and airborne experiments using IMI’s mid-range rocket and pulsers array, together with Rokar’s NavComp integrated GPS and Flight-Computer system, capable of measuring position, velocity, roll angle and roll rate. The main challenge was to design a GPS system that operates on a rolling platform, which is also capable of measuring roll angle and roll rate. The GPS system was required in order to estimate and correct the rocket’s trajectory. Flight correction was done using a pulser (propellant charge) array, which operated at the appropriate timing to correct the rocket path and to achieve target hit using an inexpensive platform. In order to use the pulsers to correct the rocket trajectory the GPS receiver had to measure the rocket roll angle and roll rate. The paper describes the following subjects: • Description of various Rocket steering methods • Abstracts of Principles of Rocket Guidance via Pulsers • TechRoll System description • NavComp system description • Description of the design approval tests • Summary and conclusions The following capabilities were demonstrated: • Full GPS navigation up to 13 Hz roll rate • Roll angle measurement using GPS, with an accuracy better than 5° • A steering mechanism using low-cost pulser charges The project experiments have successfully demonstrated the feasibility of using GPS as a primary means of navigation and rocket roll measurement and a pulser array as a rocket trajectory correction facility.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	58 - 61
Cite this article:	Malul, Assaf, Keynan, Tzafrir, Newman, Danny, "Rocket Trajectory Correction Using Pulsers Mechanism and a GPS Receiver for Roll Rate & Angle Estimation," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 58-61.
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