FixTheRobot Explore Robotics / Guidance, Navigation and Control / M7 / M7-L3

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Guidance, Navigation and Control · Aided Navigation and Attitude Determination · M7-L3 · Advanced

Ride Through the Outage

Bench log · Hopper on the test range

14:40. Hopper lost all but one of its range beacons for a minute behind the test tower, and came back with a position that was 12 m off. Then the beacons returned and, a quarter of a minute later, one of them started to read 40 m long; the position jumped again.

You will see what coupling does through the outage, write the measurement update, and write the gate that stops one bad beacon from moving the vehicle.

Your task

    Simulation
    solution.pyLoading Python…
    Ctrl+Enter runs
    What Python can I use?

    Plain Python 3 with the standard library and the course library gnckit (import gnckit as g: transfer functions and margins, state space and LQR, the Hopper model, quaternions, a convex solver). NumPy is not available in the browser. Your code runs in a background worker: an endless loop is stopped after a few seconds and the page stays usable. It runs in your browser and is never sent anywhere.

    Hints

    What this lab teaches

    Stage 1: during an outage the INS drifts with its bias; a tightly coupled filter keeps using the one visible range and a loosely coupled one has nothing to use; after the beacons return a gate on the normalized innovation rejects the fault. Stage 2: the measurement update, with the innovation covariance H P H′ + R. Stage 3: the gate in normalized units, which scales with the filter's own uncertainty.

    Grading evaluates the error of your chosen configuration over the outage and after the return on hidden noise realizations, compares your update with the reference to 1e-9, and checks your gate decisions on hidden innovations.

    Theory for this lab

    Aided Navigation and Attitude Determination labs

    1. M7-L1: Solve the Fix
    2. M7-L2: Two Vectors, One Attitude
    3. M7-L3: Ride Through the Outage: this lab.

    Educational simplification: one dimension along the track, three beacons, a constant accelerometer bias and a single fault; module 7 and the integrity lesson treat several faults, protection levels and the geometry of detection.

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