Wheelhaus
Veteran
Location: Denver
| Probably RCGroups, there's a lot of AP stuff there.
Anyways, the purpose of the SL720 gyros being used specifically for cyclic control is based on a few simple factors.
One, tail rotor control is MUCH different than main rotor control. The movement and dynamics are nothing alike. What does that mean? Gyros are built for tail control, period. The type of feedback loop and internal programming are hard-coded and designed to work for a tail specifically. Putting a gyro on cyclic duty will mean that the movement and feedback is entirely different, so the gyro must be programmed accordingly. This is REALLY important for 3D when systems are being pushed to their limits. a high end gyro can cope with this dynamic strain, but it needs the capability of being programmed with the right parameters so it understand what the dynamics are. Essentially it becomes "fly by wire" and the computer is making all the decisions. Your inputs are only suggestions.
Two, the SL720's are high end gyros, and they output only digital servo signals at a high framerate. Analog servos can only handle about 50-70 signals per second, but digital servos are anywhere from 150-300+ frames per second. Driving an analog servo at a higher framerate than it was designed will burn it up, if it even works. This means MUCH smoother control and much much quicker response. CSM's Cyclock mixer is designed to handle both standard and high framerate inputs (incase you're using a SL720 gyro) thus making it fully compatible. The AP2000i cannot accept high framerate inputs.
Since the Gyros function on a single axis, your Tx needs to be programmed for standard single servo (non CCPM). Just like the tail, the signal jumps from Tx to Rx, goes into the gyro, then to the servo. If you have a CCPM heli, then you need a mixer to mix the independent channels into a 3-servo CCPM output. This has to be done after the gyro's have adjusted the signal, so it must be done onboard.
The gyro's signals and collective signal all go into the mixer and it then creates the CCPM output to control 3 servos. Mikado's V-Stabi is an "all-in-one". It comes with the mixer/computer unit, as well as a single small case (smaller than a 401) that contains 3 high end gyros (one for tail, elevator, and aileron) to each control one of the 3 rotational axes. This would be equivalent do buying CSM's Cyclock and three SL720 gyros.
If you want to use gyros simply to help control a flybarless head used specifically for AP, then you may be able to use the GY401 (or other similar "standard" gyro). I have no experience with them on cyclic, but I know some people have managed to get them to work successfully.
..........
Dave
TT e620 SE and Mini Titan |
