Ryan Malloy
c93bbef26d
Extract Gabe Emerson's Trav'ler rotor scripts into a proper Python library with firmware protocol abstraction (HAL 2.05 + HAL 0.0.00), Hamlib rotctld TCP server, Click CLI, and isolated leap-frog algorithm with the elevation copy-paste bug fixed.
51 lines
1.8 KiB
Python
51 lines
1.8 KiB
Python
"""Leap-frog prediction algorithm for mechanical lag compensation.
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The Trav'ler dish has inherent mechanical lag — by the time the motors
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reach the commanded position, a satellite in motion has already moved on.
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This module applies a small predictive overshoot so the dish "leaps ahead"
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of the target, reducing tracking error during a pass.
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"""
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def apply_leapfrog(
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target_az: float,
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target_el: float,
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current_az: float,
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current_el: float,
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) -> tuple[float, float]:
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"""Apply predictive overshoot to compensate for mechanical lag.
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For each axis, if the delta exceeds a threshold, the target is nudged
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further in the direction of travel. This keeps the dish slightly ahead
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of fast-moving satellites.
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Args:
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target_az: Desired azimuth from tracking software (degrees).
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target_el: Desired elevation from tracking software (degrees).
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current_az: Last-known azimuth of the dish (degrees).
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current_el: Last-known elevation of the dish (degrees).
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Returns:
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Adjusted (azimuth, elevation) with overshoot applied.
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Note:
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The original upstream code had a copy-paste bug where the elevation
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delta adjustments modified target_az instead of target_el.
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See docs/bugs.md for details.
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"""
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# Azimuth compensation
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az_delta = target_az - current_az
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if abs(az_delta) > 2:
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target_az += 1.0 if az_delta > 0 else -1.0
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elif abs(az_delta) > 1:
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target_az += 0.5 if az_delta > 0 else -0.5
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# Elevation compensation (bug fix: original modified target_az here)
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el_delta = target_el - current_el
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if abs(el_delta) > 2:
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target_el += 1.0 if el_delta > 0 else -1.0
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elif abs(el_delta) > 1:
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target_el += 0.5 if el_delta > 0 else -0.5
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return target_az, target_el
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