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Offline Lotuswins

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Motor Noise
« on: February 20, 2019, 11:46:21 AM »
Hi Luke,

So I've had a recurring problem with motor noise I believe.  What will happen is I'll be driving a tank around, and I'll have the smoker running or elevating the gun, etc., and I will get a 'hit' sound and the drive motor will go into reduced speed just like when in battle and you get hit by another tank via IR. 

This morning I got it while driving my almost completed SU152 which has no IR installed as yet, and only the smoker (new Taigen V2 unit) was running. 

A couple of questions:

Is there a way to return the TCB to normal status after a hit without having to go to the tank and cycle the power switch?

Are there better ways to filter motor noise from interacting with the TCB other than the normal 0.01uf caps that come installed from the factory?  Or possibly a better quality size 130 motor that would not be so susceptible to noise?

I've disassembled several of the small motors, cleaned the comms, and brushes, and put new caps on with some success but not always.  Often the little motors will only have a single cap between the brushes, and one brush tied to the motor case, since it is normally isolated from any ground/frame element. 

Thanks as always, keep up the great work!!

Jerry

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Offline LukeZ

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Re: Motor Noise
« Reply #1 on: February 20, 2019, 06:28:28 PM »
Hi Jerry,

There have been many threads such as this one that start off with an unproven premise. Motor noise is of course a real thing, and can cause issues, and maybe your models suffer from it, but I can't imagine any scenario where motor noise would cause the TCB to think it had received an IR hit, especially if no IR receiver is attached. It is simply not possible.

Now it is quite possible that electrical interference could cause your sound card to play the hit sound, or any other sound, that is much more easily done. But if the TCB is registering a hit without actually being hit, something else is going on besides motor noise.

To definitively know if the TCB has registered a hit, you would need to be attached to your computer in Snoop mode. Or, you could attach the hit notification LEDs to the APPLE connector (but leave off the IR receiver). If you receive a hit there will be a very distinct pattern of fading in and out shown on the hit notification LED (if you are not using a Tamiya apple, be sure to add resistors to these notification LEDs).

Short of that confirmation, I can't as yet feel confident that what has happened is what you think has happened. And even if it did, we would need to look elsewhere besides motor noise, because that is not related to IR reception.

Is there a way to return the TCB to normal status after a hit without having to go to the tank and cycle the power switch?
No, the usual way to return to normal status is for the tank to be hit enough times that it is "destroyed" after which it regenerates automatically after 15 seconds in line with the Tamiya battle standard. But since you are not actually in a battle, the only way to clear it is reboot.

You can however on the Battle tab of OP Config select Disable IR under both the Cannon and MG sections, which should turn off the functionality completely.

Are there better ways to filter motor noise from interacting with the TCB other than the normal 0.01uf caps that come installed from the factory?  Or possibly a better quality size 130 motor that would not be so susceptible to noise?
I am no expert on motor noises so I think you already know more than I do if you have been disassembling them. What I can say is be sure to keep your motor wires (meaning the wires running from whatever ESC you are using to the motors) as far away as possible from your receiver and its cable to the TCB, as well as any servo leads to your sound card, as well as from the power leads to the TCB.

Some modern receivers support two-way communication and in essence these receivers are also transmitters in their own right. I don't know what receiver you're using but in those cases you want to keep the receiver antennas away from the TCB as well.

These are always good practices but again even in the worst case scenarios would not be capable of fooling the TCB into thinking it had received an IR hit. So experiment with them, but you will need to do some more troubleshooting to more clearly define the offending behavior before we can analyze further.
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Offline Lotuswins

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Re: Motor Noise
« Reply #2 on: February 22, 2019, 12:43:19 PM »
Hi Luke,

Thanks for the usual prompt reply.

I had another issue, coincidentally with this same chassis/TCB, a while ago.  This chassis has the HK 45A ESC's, taigen gearset, FRSKY receiver, and Benedini sound card.  So this is really a neat one. 

The original smoker on this runs on tank startup.  When started, about 50% of the time, the main drive motors would chatter with no throttle input.  Once throttle input was on, it would drive okay, but stop it and the drive motors would start chattering again.  Turn off the smoker, and the chattering would stop. Very repeatable.  So I removed the smoker motor and found the commutator and brushes (if you can call them brushes - thin copper strips) coated in oil.  My theory is that since these motors do run at high rpm, the brushes would lift slightly due to the hydraulic wedge created by the oil causing arcing on the comm, evidenced by the black carbon in the oil. The arcing was causing the noise on the smoker circuit power, which in turn, impacted the ESC controls through the PWM connection. 

Once I cleaned the commutator and brushes the problem went away. 

I will try to recreate the 'hit' sequence on the SU152 to see if I can get it to go again.  Unfortunately it so far has been few and far between instances.  As a side note the receiver is way up front on this tank, and the smoker is at the rear, just in front of the main drive motors. 

thanks again, jerry

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Offline LukeZ

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Re: Motor Noise
« Reply #3 on: February 24, 2019, 03:08:52 PM »
Well that was quite the investigation on the smoker motor issue, but good work on solving it.

If you can recreate the IR hit behavior then let  me know, but of course intermittent problems are always the hardest to pin down (unlike your smoker noise, this one is not repeatable). In the meantime, disable cannon and MG IR in OP Config. That way, even if you did have an IR receiver connected, and even if you did receive a direct hit from a legitimate IR battle source, your tank would still not respond.

I don't know which exact FrSky receiver you're using, but most do implement two-way communication. Be sure to keep the receiver's antennas away from the Benedini (and any other PWM cable), because that certainly can cause sound card issues.
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Offline Lotuswins

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Re: Motor Noise
« Reply #4 on: April 18, 2019, 08:45:59 PM »
Hi Luke,

So I ran the SU-152 around for 10 minutes w/o smoker....no repeat occurrence, then turned on the smoker and after a full 4 minutes or so it finally recorded a hit.  Then the next day, I tried again and it wouldn't occur....

So I moved on to my Panther, which was acting up with the gun elevation motor.  I would get varied issues by running this motor, including: hit, transmission off, transmission engaged, cannon fire, servo for volume pot would constantly chatter.....weird.  And very repeatable, fortunately.  It didn't do it with the rotation motor, nor smoker, so far. 

First I thought it was the motor, so I removed it and cleaned the commutator and brushes, then reassembled it all, and bingo....nothing.  Then I replaced the motor, nothing. Still had all the previous issues.  So I hooked it up to Snoop and got: Cannon Hit (Tamiya 2 shot), Health level 50%, Turn Engine On, engage Transmission, Turn Engine Off, RADIO FAILSAFE, Radio Ready PPM, MG Stop, Airsoft-Disable..... quite active?

Second I thought perhaps interaction of the E&M fields with the cable going up to the hull, which is a Taigen 8 pin cable with added wire but twisted and of the small size that they provide on stock tanks.  So I replaced all that with larger wire, not twisted.   No joy....still had the issue.

So I removed the motor again, and plugged it in right at the TCB, and bingo all was good.....ran it up/down/reverse....all good....hmmmmm.

Then I bypassed the Taigen slipring, which is the largest one available since I have IR and Airsoft in the turret......and only got a single Cannon Hit, once.  None since. 

So, what do you think?  Arcing inside the slipring?? I haven't dissected one before so I'm not familiar with the construction, but clearly it has issues....

So, now back to that SU-152......if it will ever repeat,

Jerry

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Offline Lotuswins

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Re: Motor Noise
« Reply #5 on: April 18, 2019, 10:49:14 PM »
So curiosity got the better of me on the slip rings.....looks like ring 3 & 4 are almost/are touching....

Major light duty to run a motor, two brass 'hairs' per slip ring. 
slipring.JPG
Motor Noise slipring.JPG
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Offline Lotuswins

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Re: Motor Noise
« Reply #6 on: April 19, 2019, 01:42:51 PM »
Okay, so the Panther isn't done with me, apparently its mad and is taking out revenge.

While driving the thing around, moving the turret as well as moving, I get a 'hit' and health goes to 50%.  Then, repeating the same, the tank gets destroyed.  Hmmm....

So I put it on the bench connected to Snoop, and after starting the tank, stopping the smoker I move fwd, then rev, then rotate the turret...here is the snap shot:


Radio Ready - SBus

---------------------------------------------
FIRMWARE VERSION: 0.93.46

---------------------------------------------
RADIO INFO - SBus
---------------------------------------------
Stick       Min    Center   Max    Deadband  Reversed
---------------------------------------------
Throttle    988    1500     2012    25        FALSE
Turn        989    1501     2012    25        FALSE
Elevation  1024    1500     1977    25        FALSE
Azimuth    1024    1500     1977    25        FALSE

Aux Chan.   Min     Max     Type
---------------------------------------------
1           988     2012    Digital
2           988     2012    Digital
3           988     2013    Analog
4           1500    1501    Digital
5           880     1500    Analog
6           880     1500    Analog
7           880     1500    Analog
8           880     1500    Analog
9           880     1500    Analog
10          880     1500    Analog
11          880     1500    Analog
12          880     1500    Analog
---------------------------------------------
Channels detected: 16
Channels utilized: 16

---------------------------------------------
MOTOR TYPES
---------------------------------------------
Drive Motors:      Sabertooth Serial
Turret Rotation:   Onboard Motor Driver (A)
Barrel Elevation:  Onboard Motor Driver (B)
Mechanical Barrel: Airsoft (Disabled)

---------------------------------------------
DRIVE SETTINGS
---------------------------------------------
Vehicle Type:           Tank
Active Driving Profile: 1
Accel Ramp Enabled:     No
Decel Ramp Enabled:     No
Motor Nudge Enabled:    No
Forward Speed Limited:  No
Reverse Speed Limited:  Yes - 50%
Transmission Type:      Automatic
Shift Time:             0.0 sec
Engine Pause Time:      0.0 sec
Transmission Delay:     0.0 sec
Neutral Turn Allowed:   No
Turn Mode:              2
Track Recoil Enabled:   Yes (Kickback speed 40%, Deceleration factor 30)

---------------------------------------------
TURRET SETTINGS
---------------------------------------------
Turret Rotation Speed Limited:  No
Barrel Elevation Speed Limited: No
Recoil delay:                   No

---------------------------------------------
BATTLE INFO
---------------------------------------------
Is Repair Tank?   No
Fire Protocol:    Tamiya
Hit Protocol 2:   Taigen V1
Repaired by:      IBU Repair
Send MG IR Code:  No
Accept MG Damage: No
Damage Profile:   Tamiya Spec
Weight Class:     Medium
(6 cannon hits, 5.0 sec reload, 12.0 sec recovery)

---------------------------------------------
SOUND CARD
---------------------------------------------
Sound card: Taigen Sound Card

---------------------------------------------
FUNCTION TRIGGERS
---------------------------------------------
Turret stick functions: Yes
Turret movement delay:  0.35 sec
Turret Stick - Top Left       -> Function #1   - Engine - Toggle On/Off
Turret Stick - Top Right      -> Function #7   - Cannon Fire
Turret Stick - Bottom Right   -> Function #16  - Light 1 (Headlights) - Toggle On/Off
Turret Stick - Bottom Left    -> Function #84  - Smoker - Toggle
Aux Channel  2 - Pos 2 (of 2) -> Function #11  - Machine Gun - Fire
Aux Channel  2 - Pos 1 (of 2) -> Function #12  - Machine Gun - Stop
Aux Channel  3 - Variable     -> Function #56  - RC Output 2 - Pass-through
Aux Channel  1 - Pos 2 (of 2) -> Function #13  - Airsoft/Mech Recoil - Enable
Aux Channel  1 - Pos 1 (of 2) -> Function #14  - Airsoft/Mech Recoil - Disable

---------------------------------------------
BATTERY
---------------------------------------------
Battery Detected: Yes
Voltage:          5.15v
LVC Enabled:      Yes (6.3v cutoff)

---------------------------------------------
BAUD RATES
---------------------------------------------
USB Serial Baud:   115200
Motor Serial Baud: 38400
Aux Serial Baud:   115200
Serial 3 Tx Baud:  38400

---------------------------------------------
MG Stop
Airsoft - Disabled
LVC threshold reached! (6.3v)
LVC Exit - Voltage Restored
Turn Engine On
Engage Transmission
Smoker disabled
Moving Forward
Stopped
Moving Reverse
Stopped
CANNON HIT! (Tamiya 2-Shot)
Health Level: 50%
CANNON HIT! (Tamiya 2-Shot)
Health Level: 0%

TANK DESTROYED
Turn Engine Off
Turn Engine On
Engage Transmission
TANK RESTORED

Thoughts??

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Offline LukeZ

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Re: Motor Noise
« Reply #7 on: April 19, 2019, 04:19:40 PM »
I think you have identified the problem with random hits, and it is the slip-ring. This is not the first report of such a thing, I remember Erik from Taigen encountering something similar all the way back in 2016. I should have asked about the slip-ring but didn't think about it.

The slip-ring is literally an electrical noise generator. You have IR enabled and you have the IR connections running through the slip-ring. Some tanks use intricate IR protocols that actually contain digital information (FOV and VsTank in particular) that would be difficult to spoof, but others use very simple protocols, none more simple than the Tamiya, and none more simple than the Tamiya 2-shot kill (two pulses separated by a short length of time, that's it). Random noise on the IR signal line would easily be interpreted as an IR hit. Since the slip-ring has 14 signals passing within millimeters of each other, not to mention arcing, it is almost unavoidable that something indistinguishable from an IR signal will be detected.

The unfortunate answer is that IR functionality is not compatible with the slip-ring system. I wouldn't be surprised if it causes problems even on stock Taigen models, but no one running stock Taigen models ever uses IR so we don't hear about it (however it is also true the Taigen signal is more complex than the Tamiya).

Now this may not answer all your questions, and presumably there is no slip-ring on your SU-152 so that one remains something of a mystery for the time being. But if you disable IR reception on the Panther, or if you run the IR wires directly (bypassing the slip-ring), you should no longer receive random hits.

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Offline Lotuswins

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Re: Motor Noise
« Reply #8 on: April 19, 2019, 04:50:50 PM »
Hi Luke,

Thanks for the details, that really helps.  The snoop readout for the Panther is after I removed the slip ring, so the simple Tamiya 2 shot code makes a lot of sense.  Those little motors can spike up to 1 amp when being reversed (hooked up my Fluke to a spare), with no load. 

Both the SU152 and Panther have the wires for the IR mushroom run all the way to the top of the tank.  I'd rather not turn of the IR, but would it be prudent to put a high value resistor from the signal to ground at the hull connector?  Say a meg or so to shunt any weak, noise signal?

Thanks for all the help!! 

PS, any truth to the rumor there may be another manufacturer looking into making the TCB? 

Jerry

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Offline LukeZ

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Re: Motor Noise
« Reply #9 on: April 19, 2019, 05:31:52 PM »
Ok, so apparently even without the slipring the IR receiver is still sensitive enough to interpret interference as a hit. I think it's telling that it reads the Tamiya 2-shot, which would be about the easiest to mistake.

I'm not sure the resistor to ground would do much, but it wouldn't hurt so you could try it. Probably more effective would be to use a shielded cable and also to bypass the hull connector (would require plugging/unplugging at the TCB itself, not very convenient). Of course to the extent possible you can also try to route the IR wires away from any motor/servo wires, also away from the receiver especially if it is a two-way version. Understandably in a small model with a million wires this can be hard to do, and of course as soon as the turret begins to turn the wires are going to shift around anyway...

If we were designing model tank systems from scratch today we could eliminate this issue by using a more robust IR protocol such as the FOV signals which could not be mistaken for noise and would have the added benefit of being able to transmit actual information - allowing teams, opponent weight class identification or different types of ammunition, etc... But Tamiya has become the standard and so that is what we have.

PS, any truth to the rumor there may be another manufacturer looking into making the TCB?
I can confirm no such rumor, and I'm curious as to where it came from? I myself had not heard it until now, pretty bad when I'm not even up to speed on my own rumors! :D
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Offline Lotuswins

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Re: Motor Noise
« Reply #10 on: April 19, 2019, 08:30:41 PM »
I tried putting a 1.5M resistor from 5vdc to the signal at the mushroom base (the signal apparently is high until triggered, according to my fluke), no joy....then to negative, still no joy.  The good news is when I plug a mushroom into the base, I can't get it to trigger the hit.  Nice to have something that is repeatable.  I'll try the shielded cable next, if I can find a flexible one, the one I do have has a stiff sheath, and is 4 conductor.  I thought of just having a dummy mushroom, with just a single IR receiver but the hatch is too close to the base for that to work.  How about just shorting the +5vdc to the signal wire....keeping it high until a mushroom is substituted in place of the shorting lead?

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Offline LukeZ

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Re: Motor Noise
« Reply #11 on: April 19, 2019, 11:16:11 PM »
The good news is when I plug a mushroom into the base, I can't get it to trigger the hit.  Nice to have something that is repeatable.
This is more good information, I had assumed the mushroom was attached.

Possibly what might be nice to add is a function to enable/disable the IR features. That way you can easily disable the IR functionality from your transmitter when the mushroom is not attached, but you can also easily re-enable it when you want to battle, and in either case you won't have to fool with re-connecting to OP Config.

If one is out of channels on the transmitter, this would be a good use case for attaching a physical switch to one of the general purpose I/O ports that would then be mapped to the IR enable/disable function. You could disable IR with the flick of a switch when the mushroom is not attached, or re-enable it when it is, and avoid again having to mess with connecting to the computer.

I will add this function when I next have an opportunity and let you know when it's done.


How about just shorting the +5vdc to the signal wire....keeping it high until a mushroom is substituted in place of the shorting lead?
That would probably work quite well. There is also an option in the hardware to enable an internal pullup resistor inside the microprocessor, reading your idea let me to examine the source code and I see this internal pullup is not enabled. I think it could be without deleterious effect, and that would accomplish the same thing. I will make that change as well and again let you know when the firmware has been updated.

Hopefully one or both of these changes will correct this flaky behavior. I really appreciate your in-depth investigation which after all this time has led us to some (hopefully) fruitful options.
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Offline Lotuswins

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Re: Motor Noise
« Reply #12 on: April 20, 2019, 10:53:58 AM »
Adding an enable/disable toggle option for IR would really be awesome.  If, while you are in there, it could have a visual feedback to the operator via the flash LED it would help establish the state of the tank......three flashes it is enabled, a long one it is disabled....or something like that? Most of my tanks with the TCB still only have 7 channels used:

Channel 5: airsoft enable/disable
Channel 6: machine gun toggle
Channel 7: Volume  control either mapped to a servo driven pot (Taigen board) or a 3 position switch (benedini)
Channel 8: open for use mostly.....

I only have one tank using 9 channels, a T55A (tiran 4 colors), which has all those lights working and the machine gun cupola rotates via a servo.  Its the most animated tank so far.

Though, actually, most do now have the XJT module xmtr, with XSR receivers and 16 channels......so channels aren't a problem.....but a switch to throw mechanically would be a good option for those that don't have an available channel.

I have a switch available on my xmtrs too, ON2 isn't being used, which is half of the three position switch just right of center above the right stick.....up is to turn the tank on, and down used to turn on inertia but I haven't that enabled anywhere anymore. 

So I won't do anything on the Panther until you are able to maybe get something going so it can be tested, since it seems to be a good test bed.

Thanks so much for the help/support!!!

jerry

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Offline Lotuswins

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Re: Motor Noise
« Reply #13 on: April 20, 2019, 11:05:31 AM »

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Offline LukeZ

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Re: Motor Noise
« Reply #14 on: April 23, 2019, 05:58:25 PM »
Ok I've added enable/disable/toggle functions for IR. I also enabled the internal pull-up resistor on the receive line, which may in itself possibly solve your problem (it has the same effect as holding the receive line to +5 volts). If you want to test, the first thing to do would be to update the firmware (0.93.47) but leave the rest of your setup the same - keep IR enabled, and leave your mushroom unplugged. Drive around, move the turret/whatever, and see if you get a false hit again. If not, then that takes care of that.

But if you do still get false hits, then you'll want to utilize the enable/disable IR functions through some switch or channel on your transmitter. I've added visual confirmation through the hit LEDs, you can see this illustrated towards the end of the video below.

As another confirmation, if you are connected in Snoop and fire the cannon it will now specify whether the IR signal was also sent as part of the cannon fire event or not.

Let me know if you have any issues!

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