Tune orbital period of spacecraft using kRPC

tune_period.py

import krpc, time

target_period = 7435  # The target orbital period in seconds

conn = krpc.connect()
vessel = conn.space_center.active_vessel
period = conn.add_stream(getattr, vessel.orbit, 'period')

vessel.control.throttle = 0.0
autopilot = vessel.auto_pilot
autopilot.engage()
autopilot.reference_frame = vessel.orbital_reference_frame
autopilot.attenuation_angle = (0.1, 0.1, 0.1)

def error():
    return target_period - period()


def set_thrust_limit(n):
    if 0 <= n <= 1:
        for engine in vessel.parts.engines:
            engine.thrust_limit = n


while abs(error()) > 0.00001:
    if error() > 0:
        autopilot.target_heading = 0
    else:
        autopilot.target_heading = 180
    autopilot.wait()

    set_thrust_limit(abs(error()) / 100.0)

    vessel.control.throttle = 1.0
    scale = 1 / error()
    last = abs(error())

    while vessel.control.throttle > 0.01 and abs(error()) <= last:
        vessel.control.throttle = scale * error()
        last = abs(error())
        print(error())

vessel.control.throttle = 0
time.sleep(0.5)
set_thrust_limit(1)