ArduRover Mower - Straight-Line Wheel Tracking Method (no encoders)

Рет қаралды 4,304

2 жыл бұрын

Since the mower does not use an ESC or wheel encoders, it's important to precisely tune the transaxle drive servo PWM values to achieve straight line tracking at max forward, max reverse, and part throttle.
I used an ESP32 to make my own web-enabled tachometer as well as Mission Planner's Python script capabilities.
Web Tachometer on GitHub:
github.com/yuri-rage/WebTacho...
Servo Tuner Mission Planner Script:
github.com/yuri-rage/ArduRove...
Find me on the ArduPilot Discuss Forums:
discuss.ardupilot.org/

Пікірлер: 26

@KennyTrussell 2 жыл бұрын

This is a great step up from the visual method I first used. The tach I used the last time was also a cheapy. It took me a bit to figure out where to put the reflective tape so that the tach would only see it and not every little bump in the tire. The magnets and hall effect is great! Thanks as always.

@danekouttron8768 2 жыл бұрын

I like the simplicity of this test setup, wayyyy more accurate than driving and adjusting the trim on the fly. Thanks!

@YurisHomebrewDIY 2 жыл бұрын

To be clear, it can be done with one of those handheld tachs, but the one I bought was all but useless. There are better available if you don’t want to go to the trouble of building a Hall effect tachometer for yourself.

@SimplyShale 2 жыл бұрын

Yuri, are you a wizard? This is just great great stuff.

@user-xh4qb3bv4p 2 жыл бұрын

Seriously cool, Yuri.

@bitdog7057 2 жыл бұрын

Thank you for this idea and the code!

@fundude2 2 жыл бұрын

You da man! I'm going to take it upon myself this coming year to really observe you videos and hopefully catch up to where you are. It take a lot of knowledge to make some things looks simple. There is a lot of R and D that goes on behind the scenes that I can appreciate. Had a a big laugh when you said "this thing is a f ing piece of shit and I'm going to throw it in the trash" -something I would say

@gregmoser2086 Жыл бұрын

I love this approach. Only question I have is how accurate does it remain in the field? I used to cut lawns and had a walk behind mower that the tire would slowly lose air and the tire diameter differential would make the mower travel one way more than the other. Not sure if there is an "on vehicle" option to adjust on the fly on your mower?

@YurisHomebrewDIY Жыл бұрын

This approach works really well to get as close as you can get under ideal circumstances. The rate/nav controllers in the autopilot take care of any inconsistencies. In practice, I see little to no change over time.

@scottykify 25 күн бұрын

I've been messing around with a Pixhawk 6c and Here4 GPS antenna and wheel encoders have caught my eye you would think they provide very valuable information on yaw movement so why not permanently install wheel encoders? I would assume there is a setting in pixhawk to use encoder data with a certain "weight" applied, along with GPS and Compass Data to really pin point yaw movement.

@Island.dweller 2 жыл бұрын

Great Videos! Just found your channel. Last year I did the covid diy powerwall -- this winter Id Like to attempt this. I found a electric mower that I want to run off of smaller 24V 18650 packs that can charge off of my solar system. Do you reccomend servo motors for drive motors? I was thinking wheelchair worm drive? Cheers Ryan

@YurisHomebrewDIY 2 жыл бұрын

I have no significant experience with using electric motors for an ArduPilot Rover, but servos might be a good choice since you get a built-in encoder. Otherwise, wheelchair motors seem very attractive since they are cheap and powerful.

@mtrunk8570 2 жыл бұрын

I have a setup like kenny with a pixhawk package from amazon. I am wondering if I could expect it to even hit the waypoints. at the current it just goes in a CCW circle of about 50ft sometimes it backs up. I have been round and round with motor configs. any tip. to make it even hit the waypoint. I am new at this so I could be overlooking something. Thank for this video.

@YurisHomebrewDIY 2 жыл бұрын

Of course it can be expected to hit waypoints. Try joining the ArduPilot Discuss forum for more direct help.

@mtrunk8570 Жыл бұрын

@@YurisHomebrewDIY Thank you

@SimplyShale 2 жыл бұрын

So, if/when I get into this over the winter, I'm thinking...how about creating a hub adapter from and automotive ABS sensor picked off a junkyard car? They seem to be similar to mouse wheel sensors, where gaps in a rotating wheel create pulses, but with ABS I think it's magnet on one side, sensor on the other, and gaps in the steel to generate pulses.

@YurisHomebrewDIY 2 жыл бұрын

Likely a great way to incorporate an encoder!

@chriscooper5161 2 жыл бұрын

Do you always mow at full engine throttle? I've had trouble determining straight line tracking as it seems to change as a function of engine rpm for me (assuming hydro or drive belt) and I usually mow low rpm ish....maybe I just need to stop that, curious if you see same change vs engine rpm.

@YurisHomebrewDIY 2 жыл бұрын

I mow at 2/3 - 3/4 engine RPM, and I did this tuning in that range, though it tends to behave similarly throughout the rev range.

@srnunan4783 2 жыл бұрын

So the servo outputs will be set from the flight controller in a loop control for yaw so won’t that take care of small inaccuracies here? Or will you be driving manual? I’d also love to get a handle on your explanation of the need to get away from magnetometers and set yaw from gps only?

@YurisHomebrewDIY 2 жыл бұрын

Certainly the flight controller takes care of any inaccuracies, but why make it calculate and react more than necessary. I do use manual mode as well, so this help there, obviously. Mowers like this are full of ferrous metal, much of it whirling around at high speed. No matter how I tried to place the magnetometers, how many I used, how/when they were calibrated, magnetometer derived yaw was always in error due to the magnetic field disturbances created by the mower. GPS yaw removes all of that frustration.

@srnunan4783 2 жыл бұрын

@@YurisHomebrewDIY Ahh OK I see now, it's about the interference from the mower itself rather than gps yaw being otherwise superior to mag based yaw. So does that mean generic ardurover is inherently unsuitable for all metal/engine driven mowers due to mag based yaw detection? If so is your gps based yaw being contributed to the ardurover community through the development of the code? Again congratulations on your success with this, it's great

@YurisHomebrewDIY 2 жыл бұрын

@@srnunan4783 GPS yaw augmented by gyro/accelerometer filtering is actually more accurate than magnetometers. It's also orders of magnitude more expensive. ArduPilot already includes support for it - I'm just among the first to have successfully used it in the field.

@Aliye727 2 жыл бұрын

hii, ı make a rover and ı have a encoder on motor how ı should active on pixhawk cube, ı can read the ardupilot document ı have a and b signal cable

@dgb5820 2 жыл бұрын

Yuri love your work, but why can’t you add an encoder or did I miss something. I have come back to this and now realise how clever this calibration is. This make the hydrostat user friendly

@YurisHomebrewDIY 2 жыл бұрын

It’s not that I can’t add one, but rather that I don’t want the added complexity and possible fragility of an encoder on the axle. So I added complexity to the tuning instead…