It’s not every day I get excited about a graph. This is an X Y Z trace from the Ricoh GR gimbal rig. After a lot of fiddle getting the balance and discovering 12c errors along the way, breaking tiny wires and replacing them, running calibrations over, gently re-routing cable and countless flat battery reports here is the 3D active stabilisation I have been looking for:
Smooth oposing corrections without clipping or jagged peaks show the gimbal is doing its job.
’12c errors=0′ means the gimbal will run without freezing unaccountably as the movements get bigger. The gimbal locks up because big movemets draw big current and the noise from the voltage supplied to the motors surges and wipes out the tiny IMU (12c) signal. The cure is to fit a ferrite bead (more weight..sigh) to the IMU wires as close as possible to the yaw motor (where the ‘noise’ is greatest) and separate them from the motor wires for as much of their path as possible It’s easy to forget this a digital system and see it as mechanical and expect movement to be consistent regardless of scale.
This is the trace of typical instability prior to a 12c error event:
Clearing the error takes patience: a 12c error locks up the gimbal, the re-set time is 30 seconds before connection can be regained and revised PID settings attempted.
Despite the intimidating look of the PID settings it’s not to difficult to stabilise the gimbal provided it’s in balance:
The advice is to work through them one by one starting on pitch with roll and yaw disabled. Setting D first then I, then P. Each change in value is written to the controller and effect on movement can be tested as the 9 settings are progressively brought in to play. Any change in the balance (e.g.adding a shutter release and video relay wires) needs the PIDs to be revisited after folowing the calibration routine.
Power supply. The power draw seems to be hefty, as the PID settings get more refined the draw reduces. From the connector supplied it looks like a 11.1v 3s battery is the norm. Distribution to the RC reciever means either a 2nd, lower voltage, battery is needed or a UBEC for the 5v required.
Shutter control. Gentles Ltd supply a combined shutter release and video cable (type 122) for the micro USB port on the Ricoh GR. The shutter can be deployed as a trip or hold and trip. Super fine wires are needed to thread the 4 wires through the hollow shafts to the reciever.
The next step is to equip the gimbal with RC and video relay.
The gimbal works: