[email protected] writes: > Ok, sounds good. But this means the gyro sensor is not involved in > apogee computation, right?
Correct. Rockets generally tilt over at apogee, but I have seen many slide directly backwards, making any sort of angle measurement an uncertain indication of apogee. > Speed is probably computed by integrating acceleration, while apogee > will be at the zero point of the first derivative of the acceleration, > right? Effectively yes, but each of these are done in the context of the physical model which is the predictive part of the Kalman filter. A Kalman filter is a way of estimating the state of a hidden Markov chain using noisy sensors along with a model of the Markov system itself. We're running predictive Newtonian model of the rocket assuming a constant acceleration (which is a good estimate near apogee), and then constantly correcting the model based on sensor input. > I guess I should have another look at the code, but I tried before and > did not find what I was looking for...I'll have a closer look on it > over the holidays :-) There's a lot of math involved in understanding why it works, but only a very small amount of arithmetic to actually fly the rocket. Kalman filters were developed for early space flight applications, including Margaret Hamilton's firmware that landed spacecraft on the moon. > One other point is that for launch sites at high latitudes GPS is very > unreliable due to the GPS satellites only having 55° inclination. Just > saying... GPS satellites are not in equatorial orbits and offer similar precision over the entire planet; we've seen poor results everywhere from Australia to Canada, and great results across the same range of locations. -keith
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