No abstract

The knowledge of the roll angle of a projectile is decisive to apply guidance and control law. For example, the goal of ISL's project GSP (Guided Supersonic Projectile) is to change the flight path of an air-defence projectile in order to correct the aim error due to the target manoeuvres. The originality of the concept is based on pyrotechnical actuators and onboard sensors which control the angular motion of the projectile. First of all, the control of the actuators requires the precise control of the roll angle of the projectile. To estimate the roll angle of the projectile, two magnetometers are embedded in the projectile to measure the projection of the earth magnetic field along radials axes of the projectiles. Then, an extended Kalman nIter is used to compute the roll angle estimation. As the rolling frequency of the GSP is about 22 Hz, it is easy to test the navigation algorithm in laboratory. So in previous papers ([1),[5)) the in-lab demonstration of this concept shows that the roll angle estimation was possible with an accuracy of about 1° at 22 Hz. In this paper, the demonstration is extended to in-flight test, with a roll rate about 35 Hz. Thus, two magnetometers, a DSP and a LED (to simulate a thruster) are embedded inside the projectile; the DSP runs an extended Kalman nIter and a guidance algorithm to compute the trigger times of the LED. By using a high speed camera (a trajectory tracker), we can observe that the LED is switch on at the target angle.

No abstract

Location is a growing problem due, for instance, to the expansion of civil drones or intelligent vehicles. This expansion was made possible through the development of microelectromecanical systems (MEMS), cheap and miniaturized inertial sensors. In this context, this article is devoted to the development of a simulator which generates the sensor measurements, giving a specific trajectory, in order to validate and compare pose estimation algorithms. After validation of the simulator with real movements and measurements, four pose estimation algorithms from the literature are compared on different trajectories. All these algorithms use magnetic field sensors in addition of the classical inertial sensors. This comparison is led to select an algorithm for a future application with multiple IMUs.

The knowledge of the roll angle of a projectile is decisive to apply guidance and control law. For example, the goal of ISL£s project GSP (Guided Supersonic Projectile) is to change the §ight path of an airdefence projectile in order to correct the aim error due to the target manoeuvres. The originality of the concept is based on pyrotechnical actuators and onboard sensors which control the angular motion of the projectile. First of all, the control of the actuators requires the precise control of the roll angle of the projectile. To estimate the roll angle of the projectile, two magnetometers are embedded in the projectile to measure the projection of the Earth magnetic ¦eld along radial axes of the projectiles. Then, an extended Kalman ¦lter (EKF) is used to compute the roll angle estimation. As the rolling frequency of the GSP is about 22 Hz, it was easy to test the navigation algorithm in laboratory. In a previous paper [1], the In-Lab demonstration of this concept showed that the roll angle estimation was possible with an accuracy of about 1• . In this paper, the demonstration is extended to high-speed roll rate, up to 1000 Hz. Thus, two magnetometers, a DSP (Digital Signal Processor) and a LED (Light Eminent Diode), are rotated using a pneumatic motor; the DSP runs an EKF and a guidance algorithm to compute the trigger times of the LED. By using a high-speed camera, the accuracy of the method can be observed and improved. GUIDED SUPERSONIC PROJECTILEFor ground-based air defence gun systems to be e¨ective, the ability to hit the target is a prerequisite. To achieve high hit probability performance against manoeuvring air targets, such as attack helicopters, cruise missiles, or unmanned air vehicles, the basic point is to ¦re projectiles having short times of §ight. However, this solution is limited by the performance of the gun.