Sebj - 8020 - Seat Mover with Traction Loss

Bit more progress. Wheel uprights installed, motors mounted.
Working now on wheel assembly, front pivot point.

moved ahead quite a bit. i am in the process of mounting and configurating motors. Hope to be done this month.

Very nice!

Got a few hickups. JrK died, possibly a short although I cant explain it because it wasnt touched - USB stopped picking it up. Diagnosed with Pololu but seems its dead. Sourcing a new one.

Will be configuring my two rear motors now and waiting on 2 mounting brackets for rear TL.

configuring simtools iracing before connecting arm
@Nick Moxley is a superstar helping me out

Its alive!

Tuning time

Hey guys, hope someone can assist me with this very strange issue.

One of my motors begins to vibrate, increase in oscillations and eventually get so bad i have to estop.
This behaviour occurs in the JRK tool as well as simtools or within game. So it has to be JRK or PSU related I'm thinking.

First thing I checked was pot mount and pot tightening. All good. Wiggling pot mount does not induce any oscillations.

I can load up say iRacing, do 3 laps and then this starts up. I hit eStop, reset to the pits and sit there, disable eStop and the oscillation continues. So I hit estop again, on/off, maybe 2 times and then sometimes it stops but comes back within a minute later.
I can also get this behaviour when I exit out of game and go right into JRK util. It will start up there.

I can test JRK target acquisition by moving the slider slowly, quickly back and forth and cant reproduce this behaviour.

sometimes it will occur when I do an output test in Simtools, and move one of the sliders like Sway for example. But not consistently always.

So I'm baffled here.

Any ideas how to isolate? check or figure out why this is happening?

I could swap PSU's and see, and then swap JRKs and see if the other motor exhibits this behaviour. I could isolate either component then. If it continues then it could be the motor itself or perhaps something else. All things are tight and i cant find anything lose that could cause oscillation.
Both motors using same connectors, cables etc.
The working motor has a 2 foot shorter power cable going from motor to controllers. Only difference. But length of cable is still under 5feet 14gauge

Havent tried swapping anything yet. Easiest thing to do first i guess.

I'm essentially running the settings provided here. i.e. 0.4,0.0,0.4 for PID, 600/600 power/acceleration, 20Hz, 2000 for integral something or other. All standard stuff.

i have a spare JRK and I could swap the PSU's tomorrow and check that way as well. First thing I'll do though is reinstall the pot mount just in case. I do have a flex coupler there in between which is tight. I cant even stop oscillation when holding the seat steady. And yet i cant start it by shaking the seat or moving the pot mount around. It just develops out of nowhere sometimes, when I'm not in rig, and just waiting on the output testing screen of simtools.

EDIT: JRK settings
Input mode Serial
Never sleep checked

Feedback settings
512 analog samples

PID
0.4 0.0 0.5
20ms
integral limit 2000
reset box checked (although it seems to uncheck this sometimes by itself when I come back to tool)

PWM 20Khz
duty cycle 500
max accel 600
brake 0
max current 0
current 149
max duty when feedback out of range 600
coast

no errors aside from power when eStop or motors off

INITIALIZED 0
INPUT_MODE SERIAL
INPUT_MINIMUM 0
INPUT_MAXIMUM 4095
OUTPUT_MINIMUM 0
OUTPUT_NEUTRAL 2048
OUTPUT_MAXIMUM 4095
INPUT_INVERT 0
INPUT_SCALING_DEGREE 0
INPUT_POWER_WITH_AUX 0
INPUT_ANALOG_SAMPLES_EXPONENT 5
INPUT_DISCONNECT_MINIMUM 0
INPUT_DISCONNECT_MAXIMUM 4095
INPUT_NEUTRAL_MAXIMUM 2048
INPUT_NEUTRAL_MINIMUM 2048
SERIAL_MODE USB_DUAL_PORT
SERIAL_FIXED_BAUD_RATE 9600
SERIAL_TIMEOUT 0
SERIAL_ENABLE_CRC 0
SERIAL_NEVER_SUSPEND 1
SERIAL_DEVICE_NUMBER 11
FEEDBACK_MODE ANALOG
FEEDBACK_MINIMUM 1332
FEEDBACK_MAXIMUM 2855
FEEDBACK_INVERT 0
FEEDBACK_POWER_WITH_AUX 0
FEEDBACK_DEAD_ZONE 0
FEEDBACK_ANALOG_SAMPLES_EXPONENT 7
FEEDBACK_DISCONNECT_MINIMUM 666
FEEDBACK_DISCONNECT_MAXIMUM 3475
PROPORTIONAL_MULTIPLIER 1
PROPORTIONAL_EXPONENT 1
INTEGRAL_MULTIPLIER 0
INTEGRAL_EXPONENT 0
DERIVATIVE_MULTIPLIER 1
DERIVATIVE_EXPONENT 1
PID_PERIOD 20
PID_INTEGRAL_LIMIT 2000
PID_RESET_INTEGRAL 1
MOTOR_PWM_FREQUENCY 0
MOTOR_INVERT 1
MOTOR_MAX_DUTY_CYCLE_WHILE_FEEDBACK_OUT_OF_RANGE 600
MOTOR_MAX_ACCELERATION_FORWARD 600
MOTOR_MAX_ACCELERATION_REVERSE 600
MOTOR_MAX_DUTY_CYCLE_FORWARD 600
MOTOR_MAX_DUTY_CYCLE_REVERSE 600
MOTOR_MAX_CURRENT_FORWARD 0
MOTOR_MAX_CURRENT_REVERSE 0
MOTOR_CURRENT_CALIBRATION_FORWARD 149
MOTOR_CURRENT_CALIBRATION_REVERSE 149
MOTOR_BRAKE_DURATION_FORWARD 0
MOTOR_BRAKE_DURATION_REVERSE 0
MOTOR_COAST_WHEN_OFF 1
ERROR_ENABLE 0
ERROR_LATCH 0

Re tightened pot and pot holder. ensured no loose connections or fasteners.

so far testing in jrk util is ok. I have moved both motors back and forth quickly, slowly, quickly to extremes and in tight movements. no issue. will test in simtools next.

EDIT: went into simtools and did a few output tests, the issue presented itself again. Erratic motion.

Ok so continuing to check my Pot and worked my way back to the JRK. I noticed my 3 prong black dupont connector was a tiny bit loose. I think the heat of the JRK was causing some inconsistent feedback errors. I am changing the connector and will report back results. Hopefully this was it.

Confirming it was the loose connection and heat. Working now it seems. Will post video this week. Ill be connecting TL motor up tonight and tomorrow.

Wow! guys, simtools rocks.

I completed setup of my TL motor and ran it through some laps to configure in iracing then did some laps. Motors run nice and cold, no other issues to speak of.

I'll try to clean up the room, cables and such and then post a motion video.

cant get no limits 2 going. Its the full version. Using --telemetry in ride mode...stumped. tuning center not getting data

@Sebj ... Thanks for the pics! I am in the early stages of building these same plans ... In Series 15 extrusions tho. (It's what I have better access to.)

I struggle to see the details in my mind when trying to plan this build ... But seeing pictures really helps me get my head around it! So thank you for that!

How did you end up solving the front pivot wobble you were concerned about earlier in this thread? That is something that concerned me as well!

There is no wobble at all in the front hubs - flange bearings. that part of it is rock solid and makes no sound at all when moving. Actually, the whole rig is silent aside from the mechanical noise of the motors and seat.

There is some 'wobble' in the front of the system where the OSW is mounted because its so high relative to the bottom and the only support is the front pivot. That said, it's not really that much and in practice when racing I have not noticed it. The only way around that likely would be some castors perhaps on the front corners of the unit as well but you will still get some rocking back and forth because of the wheel assembly so i didnt think it was worth it since it doesnt interfere with driving. (I use VR btw, so notice more nuanced motion)

15 series profile, hmm, might be ok. But are you using 30mm wide pieces or is everything just 15mm? Most of my sim is in 50mm profile. (5050, 50100) <-- 25 series.

The 15 Series extrusions I am using are 1.5in x 1.5in. (38mm x 38mm) it has made a very strong rig ... I am just using what I have to reconfigure the rig to add motion.

I don't quite understand the wheel deck wobble you are describing ... Is it a side to side motion of the whole wheel stand? Could it be eliminated with more bracing?

How adjustable are the wheel and pedal positions? Anything you would change if you were building it again?