@swickliff, if only 1 out of 4 LEDs is blinking, that is very strange. When power is applied to the ESC, the bootloader on each ESC channel should always start and blink the blue led fast for 1 second. after that, firmware execution starts. If LED is not blinking at first, then there is most likely some HW issue that prevents the ESCs from booting. I am surprised that one out of four LEDs is actually blinking.

Our ESCs are all tested during production (including spinning), but if you think that you received the ESC in a non-working state (it was not damaged after receiving it), then you should submit an RMA form for a replacement. https://www.modalai.com/pages/rma

@dlee , that is great to hear!

Since lowering ESC kp and ki to zero helped, it may mean one of the several potential issues outside of ESC:

the flight controller (gyro) is measuring too much vibration from propellers (is there vibration dampening in your design?) your attitude controller Derivative gain may be too high, causing the noisy gyro data to be amplified and sent to motors

However, if the vehicle is flying well right now, perhaps you do not need to do anything else. Tuning down the ESC response acts as a low pass filter that filters out the noisy RPM commands.

@0x45 if you get it working and you would like to share your change, we can test and incorporate into the driver. That could potentially make it easier for you to not have to use a custom px4 build for your application.

@Moderator said in VOXL ESC Mini 4-in-1 Current per Motor:

Is it possible to step up voltage?

Can you please clarify the question? 🙂

Mini ESC is designed for small drones ( < 500g ). The ESC has been tested to handle 15A continous at 15V input continuously (60+ seconds), but with full direct air flow from propellers. This would simulate a full throttle "punch-out" on a small FPV drone (high current, but also lots of direct airflow = cooling). Do not use this ESC if the drone needs 10-15A per channel just to hover. Use it in application where hover current per motor is less than 5A (ideally 2-3A which is very typical) and absolute maximum continuous current per motor can be 10-15A.

For example, motors used for small FPV drones often are around 1306 size (3-4S Lipo). Those motors are usually rated for up to 10-12A continous (for 30-60 seconds). Larger motors can be used as long as maximum motor current does not exceed 10-15A (still 2-3A at hover) and there is sufficient cooling.

Always check ESC board temperature during initial flights / tuning. Temperature must stay below 110C at all times (critical), typically in the range of 40-70C for most applications. The ESC will most likely fail above 125C.

Temperature of the ESC board is the limiting factor because the board is so small. Mosfets can handle a lot of current as long as they don't overheat. So the design of the drone is very important (either use low current so that temperature is not an issue or properly design air flow from propellers and/or add heat spreader to keep the ESC board temperature in normal range for higher current draw applications).

ESC provides real time temperature feedback and it can be viewed in PX4 / QGC. Additionally, the PX4 logs contain the temperature information.

@Alex-Kushleyev Thanks for all the info! I'll keep those things in mind when soldering to the pads.

@Alex-Kushleyev Yes thank you, we will be going through all of the calibrations as our application is completely custom.

After multiple tries of updating the firmware and uploading the parameters, it seems to have finally worked!!

@blue , i just fixed (a few days ago) the calibration script (on voxl-esc dev branch) to plot the total current for M0138 in the calibration procedure, however, yes you still need to run the calibration test using ID2. This is because ID2 measures the total current and it only sends back the data if the feedback is requested from it. If you are running a test on a single ESC which is not ID2, then ID2 is not asked to send any data back, this allows for 4x the feedback rate for that single ESC that is being tested.

So on M0138 if you want to see the current output, you should use ID2 for testing:

./voxl-esc-calibrate.py --id 2 --pwm-min 10 --pwm-max 95

Currently, the current ( 🙂 ) is not used for anything in the calibration procedure, but it is good to look at it to make sure it follows a smooth curve as the power ramps up.

Thanks, I try to add as much data to plot as possible because it is often easier to spot issues by looking at the plots. By the way, it seems your data time scale is kind of coarse (seems like 14-15hz). Sometimes this can happen if your USB-to-serial adapter buffers too much data.. are you using a PC or VOXL for this test? if you are using FTDI, this may be helpful to test out : https://granitedevices.com/wiki/FTDI_Linux_USB_latency

You should be able to get really nice plots when using 2Mbit baud rate and --cmd-rate 1000 or even 2000 helps catch any small spikes or anomalies.

In your calibration test that you originally posted (where the current was reported zero), it looks like towards the end, the top left curve (commanded motor voltage vs rpm) starts curving up a bit more, that can suggest that the motor is not operating optimally at that point. I am not sure which motor / propeller you are testing, but sometimes it helps to adjust the ESC commutation advance from 0 to 20 or so (esc param <param name="timing_advance" value="20"/>). You could try that and see if the high end shape of the curve does not curve up as much.

Alex

@K-Stute , sounds great! if it happens again, let us know, we can debug.

Alex

@Chase-Riley Yes, as Alex said, most standard builds do not include the voxl_esc driver. Only the ModalAI products include it as a standard part of the build. So you will need to add that to you build configuration.

@iparra ,

There is no need to re-calibrate the ESC parameters if you replace the damaged motor and / or propeller with the identical parts. The ESC parameters are tuned to a motor/propeller type, not a specific motor / propeller unit. You can replace only the damaged components.

If the flight feels more wobbly after you replaced the damaged propeller with new one, it is possible the remaining propellers are also damaged or bent, which is causing more vibration.

Alex

@0x45 , each of the 4 ESCs sends back telemetry to PX4 at 1/4 of the update rate of PX4. On voxl2, the PX4 update rate is 800hz, so each ESC channel sends back telemetry at 200hz (round robin fashion). Only one of the four ESC channels actually measures current on the 4-in-1 mini and FPV ESCs, so you will have the current update (and hence the battery status) received at 200hz, but px4 is throttling publishing of battery status to 10hz.

Alex

@schew,

Regenerative braking happens when you command the ESC to transition from a higher speed to a lower speed. Also, if brake_to_stop parameter is set to 1, the ESC will apply braking when it is commanded to stop (0 rpm or 0 power) or it times out. If the brake_to_stop parameter is set to 0, the ESC will not brake during stopping or time out, instead the motor will spin freely (coast) to a stop.

So, brake_to_stop parameter does not affect normal operation and you should just keep that at zero, unless you REALLY need the motor to stop very fast when you disarm. (but then if you are connected to a power supply at that point, it can cause issues described here : https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-esc/-/blob/master/voxl-esc-tools/doc/regenerative_braking.md )

Turning off Regenerative Braking completely is possible on M0129 ESC, but it is not currently supported in the firmware.

So, to answer your question, if you run the ESC calibration using voxl-calibrate-esc.py script (according to these instructions : https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-esc/-/blob/master/voxl-esc-tools/calibration.md), there will not be a regenerative braking event during this procedure (unless you set brake_to_stop to 1, see above). In the calibration procedure, the ESC is commanded to increase the applied power in small steps and at the end the commands from the script stop, so ESC times out and spins down.

I have just run a test using a power supply (set to 12V) and modified calibration script, which shows voltage and current data after the calibration has finished. See plot below:
ad88ce7f-2a54-48a5-96cb-970af729443a-image.png

From the plot you can see that at t=12s, the test stops, the voltage (which was dipping during the test as current increased) comes back to 12V without overshoot and the current just drops to zero (does not become negative, which would be the case, if regenerative current was present).

I have explained what will happen if you run the esc calibration procedure (in its current version) while using a power supply. However, you should not do any aggressive spin testing with a power supply, especially step tests, where the ESC is commanded to ramp up and then down. The reason why we do not recommend doing any testing with a power supply is that it is possible to forget that the ESC is plugged into the power supply (not battery) and start performing tests which can damage the ESC or power supply. If you start hitting the Power Supply's over-current limit, voltage may drop and there could be strange behavior and ESC could de-sync.

You also need to ensure that the Power Supply can source enough current to perform the calibration. If needed, you can decrease the maximum power that is applied during calibration (using --pwm-max parameter)

So, with all that being said.. We still do not recommend testing the ESC with a power supply. If you still choose to do it, it would be at your own risk and i suggest starting by limiting --pwm-max parameter to a low value, say 40-50 and looking at the plot to ensure all the data looks similar to the plot in the calibration doc. Then gradually increase the --pwm-max parameter to 60, 70, 80, 90, checking the plot each time. You could stop at 90 and use that calibration result.

Alex

@Jeremy-Frederick, can you specify which ESC you are asking about?

The PWM pins on the ModalAI ESCs (which have the pwm signals on a connector or test pads) are bi-directional, and yes they could be used as PWM output. However, a firmware change is required and enabling PX4 to send out PWM signals is another change

We were considering enabling this feature but it is not yet implemented. Can you please provide more information about your requirements?

what type of PWM signal are you trying to send ? min/max range, update frequency, (is it one shot, or just preriodic) how often are you planning to update the value of this PWM signal? how many PWM signals do you need? what is the source for the control of PWM signal in your application (RC or something else?). The reason why I am asking, the ESC would need to receive a serial data packet from voxl_esc driver in px4, so somehow that pwm output information would need to enter the voxl_esc driver.

Alex

@restore , yeah, good plan..

@Aaky Should be fine. I fly with actual RC in HITL all the time.

@wilkinsaf , yes, you got it. By the way, you did not have to restore the old firmware, you could have just done this:

./voxl-esc-upload-firmware.py --firmware-baud-rate 57600 -f firmware/modalai_esc_firmware_m0117_1_v0_39_RC10_eb6fb500.bin --id 0

The following note does not really help, if you also have power connected to VOXL2..

WARNING: Specified ESC ID not detected; perform manual power cycle now

However, if the ESC is connected to a PC, you can just power cycle the ESC and the the bootloader will start up and firmware update will being.

Alex

@Alex-Kushleyev This forum post can be considered resolved with this answer: https://forum.modalai.com/post/17782

Thanks for the update. Cheers!