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with special interest in R/C model helicopter control
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email: tech@csm-ltd.co.uk       Tel: +44 (0)1457 854680
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ICG 540 & ICG400 GYROs: Technical information and Troubleshooting

Troubleshooting      Using the PC interface

Radio system requirements:
The gyro requires an auxiliary channel with travel adjustments to control the gyro mode/gain. It cannot be used with basic R/C systems that lack such a channel. We recommend that you use an R/C system that also provides travel adjustment on the rudder channel. Most current production computer R/C transmitters have these facilities.

Servo type selection:
Optimum performance from these gyros is obtained when they are used in conjunction with a high speed servo (0.12seconds per 60 degrees or better). On the ICG540 you can select 'super servo' or conventional servo, to allow for the faster frame rate supported by the 'super servos'.This term is the old term used to describe what are usually now simply known as digital servos, and run at a higher data frame rate (250 frames/second). The use of super servos with the ICG540 is highly recommended as they allow the gyro to fully exploit its fast response. When used with this type of servo the 'Super servo' support of the ICG540 should be activated. This can be done using the Auto setup routine, (but may also be activated via the PC interface if required). The ICG400 only runs at conventional servo speeds (super servos can be used, but the advantage of their faster speed is not used)
Warning: Use of the super servo facility with servos not designed to accept the high frame rate will result in damage to the servo. The Auto setup routine runs the servo in standard mode so it is always possible to access this routine with a standard servo even when the gyro has Super Servo support on.

Download ICG540 manual                           Download ICG400 manual

Download ICG540 PC interface manual       Download ICG540 software

Troubleshooting

The rotation rate is too slow
Increase the ATV on the rudder channel, the rotation rate is directly controlled by how far the rudder stick is deflected. Make sure you have correctly set up the left / right servo travels, once this is set the servo can not travel beyond these limits.

How do I adjust the gain?
The gain is adjusted by altering the ATV on the gain channel, increase the ATV to increase the gain and reduce the ATV value to reduce the gain. Gain is set independently for each flight mode. Be aware that some radio systems use +100 to -100, and others use 0 - 100. On these latter systems, 50% is zero gain, and to set eg. 60 % gain you need to be 60% from the centre ie 20% and 80%.

The gyro seems OK, but I can't stop it wagging in Heading Hold mode
This can be caused by a couple of conditions but the most likely cause are loose or not fully tightened boom support clamps. Try flexing the boom from side to side whilst holding the body of the model still, watch for any movement, no matter how small and get rid of it. The boom support clamp must not be able to slide on the boom. Make sure all the boom support ends are firmly attached and that none of the joints can move. Make sure that the tail linkages are smooth and slop free. A slow or low quality servo can cause this condition.

I can't get the gyro to hold as well as I expect.
The gyro, like any other component, can only work as well as the rest of the model: refer to the set-up section of the instructions to help improve the performance of the tail. As the performance of the gyro / tail of the model is probably more important than any other single function of the model to get right, expect to spend some time on this if you expect to get the best performance out of your model.

The tail constantly twitches about and will not sit still in the hover
This is caused by the gyro picking up vibration, this can be caused by an out of balance model, a rough running engine or by some component being too loosely mounted on the model. Typical examples of this are canopies, battery pack/receiver which both can cause resonance on an otherwise well balanced model.

Channel usage with JR ZPCM Receivers
The ICG540 will not enter the auto-setup routine when the gain channel is connected to AUX2 of an old style JR ZPCM receiver. If you wish to control the gain / mode of the gyro via the AUX2 switch you may do so by either of the following methods.

(a) Where a spare mixer is available simply mix the AUX2 channel function to either the 'GEAR' or AUX3 channel. Use 100% mix so that the output of this channel simply follows the AUX2 function. The gain input of the gyro can then be connected to this channel and full functionality in auto-setup and flight is then available.
Note: If the 'slave' channel is also operated by a switch then it will be advisable for safety reasons to kill the operation of this switch by the use of one of your radios free mixers.
For the PCM 10X and other PCM10 series radios the mix should be as follows.
First mix AUX2 to the 'slave' channel, this mix should be a 100% one for both switch positions, (changing both mix values from +100% to -100% will reverse the operation of the switch, you can not reverse the switch action by reversing the channel in 'Code 11'). This will have mixed AUX2 to the 'slave' channel and then to kill the switch that might be operating the 'slave' channel, mix the 'slave' channel back to itself with a -100% mix in both switch positions, this mix MUST be a negative value!! You should now be able to control the gyro gain by adjusting the value of the first mix (AUX2 to 'slave') in the same way as you would for adjusting the gain by the ATV.
With this set-up the gain cannot be adjusted by the ATV/Travel adjust. Make sure that both mixers are active for all flight modes!

The X388S set up for using AUX2 with ZPCM is basically the same as above. Unfortunately because of a software error in the X3810/8130 it is not possible to do this mix if you have the THROTTLE HOLD function active, (the JR GAIN software will not drive a free mixer), we strongly recommend the use of the 'GEAR' channel / switch with this radio.

(b) If no free mixer is available you can temporarily connect the gain input of the gyro to the 'GEAR' or AUX3 channel. You will now be able to enter and step through the auto setup routine by toggling the 'GEAR' or AUX3 channel. Once the auto setup has been completed the gain input of the gyro can be connected back to AUX2. The gyro will operate normally with the gain input coming from AUX2 whilst in flight.

There are no such restrictions with the later JR SPCM receivers or any other receiver as far as we know.

How do I use the Sanwa RD6000 with this gyro?
The Sanwa RD6000 needs to be set up in a slightly different way than usual. Please download the following word file for detailed information on the correct set-up procedure.
Download RD6000 gyro set-up information

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Using the PC interface (ICG540 only)

The PC interface for the ICG540 uses the LPT (parallel) port of your PC (not MAC): unfortunately many modern PCs no longer have an LPT port, and a 'virtual' one through a USB socket will not work. The software is DOS based and must be run from a DOS boot-up - this requires a floppy disc drive and an external one through a USB port is OK here, and are quite cheap. A DOS bootup disc can be made by formatting the floppy disc (through 'My Computer' or similar Windows systems) 'with system files' . This disc is inserted before the computer is turned on, and once booted the disc is swapped for the CSM disc and the software run directly from the floppy (do not install). The mouse may not be available to use - you may have to use the keyboard commands. If the computer will not boot from the floppy drive (goes to Windows as usual), go into the computer control system to find the order in which the computer checks the drives - the floppy drive should be set before the hard drive.

The LPT interface is the same for all CSM products so if you already have one from another product, this is fine but you will need to download the software for the ICG540 (see top of page)
LPT interfaces are still available direct from CSM - please contact us for details. We can also supply boot discs and the ICG540 software on a floppy disc.

Before any adjustments are made to the gyros internal parameters you must first get the model performing well with the factory defaults. Almost all gyro handling problems are caused by incorrect radio set up or a poor mechanical set-up, that may have been masked by a lower performance gyro. Trying to cure these problems by altering the internal gyro parameters will just be a frustrating waste of time.

The relationship between tail, boom, servo, gyro and tail blades etc. is non trivial in the way they interact so there is no decisive answer as to how changing one particular parameter will effect one single aspect without interacting with a dozen others!

Look ahead gain
This tells the gyro how fast to try and stop. For instance if there is too little 'Look Ahead Gain' the gyro will try and stop faster than the model resulting in a bounce back effect with the tail. Too much 'Look Ahead Gain' will cause the tail to hesitate during the stop.

Conventional and Heading Lock gain
'Conventional Gain' relates to the magnitude of damping and the 'Heading Lock Gain' relates to how strong the tail is held in its set position. Without Conventional gain the Heading Lock term has no damping and so will wander around constantly overshooting the mark. The analogy can be made to a car suspension system in that the Heading Lock term can be thought of the spring (always wanting to return to it's relaxed position), and Conventional gain as the oil filled damper that resists sudden changes and makes the system smooth and controllable.

Heading Lock range
This term will control how large an error the gyro will try to recover, adjusting this will have no real effect on the performance of the gyro. If however this is set too high, you could find yourself in a situation where if you have stalled the tail so the model can no longer hold against the torque, causing the model to pirouette before it recovers, once recovered the model would then try to return to its original position and so might do the same number of pirouettes in the opposite direction. By limiting this range you can prevent this situation from happening.

Heading Lock relaxation rate
This term allows you to vary the response of the tail between full heading lock and conventional: a value of zero will give you 100% heading lock and increasing values will eventually give you an increasing conventional feel with the weather cock effect.

Maximum yaw acceleration
This value lets the gyro know how fast the model can accelerate or decelerate, (governed by pitch, blade length and power available to the tail as well as vertical fin area). If this value is set too high for your model you will get stepping during pirouettes as the gyro is reacting quicker than the model can cope with. This occurs in the following manner, the pilot sets his yaw command and the gyro sees this and expects the model to rotate at a particular velocity but as the model is slow to react the gyro increases the pitch to the tail, now the extra pitch causes the tail to accelerate too quickly so the gyro then compensates and reduces the pitch but as the model is slow to react it takes more pitch off but then it realises that in fact this is too much, thus causing the stepping motion as the process constantly repeats itself.

Tail wagging and slow servos:
With some models with less than perfect set-ups or utilising lower spec servos for rudder control it may be necessary to slightly alter the parameters in mode 1 (Heading Hold). Bob Johnston has done some considerable testing in these situations and has come up with the following parameters with  much improved results.

Look ahead gain............................35%
Conventional gain..........................82%
Exponential gain............................125%
Heading lock gain......................... 88%
Direct coupling.............................. 30%
Heading lock range...................... 40%
Heading lock relaxation rate........ 2%
Stick linear sensitivity................... 10%
Stick exponential........................... 30%
Maximum yaw acceleration.......... 2550


If you have any questions or problems, please contact us on   +44 (0) 1457 854 680   or  e-mail  tech@csm-ltd.co.uk

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