Servers by jDrones

Skid Steer Mower Overshooting pivot turns

(Kenny Trussell) #141

Doug: You can have more than one GPS. The way I understand it, Ardurover will use whichever has the best position info. So, if you have an RTK fix or float status, that will be used over a standard 3Dfix. But, I am only using the ublox rtk. I figure that to do a decent job, I have to have RTK fix, so I would never want to use a lower GPS reading anyway.

(Kenny Trussell) #142

Doug and Vince: Congratulations on getting your mowers working so well! Awesome videos! You guys have a real challenge to get your navigation good enough that a 30" or less deck can do the job. I have a 72" deck so I am able to overlap a good bit to “cover up” a lot of navigation woes. I think your navigation looks pretty good. If ya’ll are interested in automatically generating waypoints for an outside-in mowing pattern, I wrote a program that will do that.

(Doug Wright) #143

Kenny" I downloaded your program a while back but my system is missing a libwinpthread-1.dll
Do you know how to fix this?
The issue I am having is my trees are covering the yard in google earth so I cant see the way points well enough.

Have you ever used the "SET Waypoint "feature in aux channel to layout a WAYPOINT file by driving it first and marking it ?
I hope they get the AUX channels expanded so we can have more AUX channels for things like this.
Do you know a better way?

(Bitdog LLC) #144

Kenny, Love the program. I’d like to convert it to a webservice / page and host it. It would make it more accessable to others. It woild be easier for me if it was C#, but I don’t think it will be too hard.

(Kenny Trussell) #145

I have used the “SET Waypoint” feature to create waypoints around the perimeter and then used my MowPlan program to generate the additional waypoints. Did you download the 2 dlls that I include in the github project and put them in the directory with the executable? If you did and still get the message about libwinpthread-1.dll, I need to look into that. On a computer that I thought was fairly clean, the 2 dlls I include were all I had to do. Maybe the one you are missing was already on that computer.

(Kenny Trussell) #146

As long as you are helping others with it with no monetary gain, please help yourself! I know it could be improved as well. It throws a random point outside the polygon occasionally, but it is easy to just move it back in, so I have not tried to fix it. It is somewhat subject to how you draw the polygon as well. I always start at the bottom right and go counterclockwise. I have planned to record a YouTube video tutorial but haven’t gotten around to it.

I also thought about using a Mission Planner polygon file for the outline rather than waypoints, but I find that I can work better with waypoints than polygons inside Mission Planner.

I am a C-programmer, by the way, mostly embedded stuff. I’m not so good with C++, but the clipper library was C++. I try to do a good job of well organized and readable code, BUT, in the C++ world, I probably did not do a good job. I’m sure you can help out.

Please have at it!!!

Let me know if I can help you in any way.

(Benjamin Neilson) #147

@Kevin_Groba, @ktrussell,

Happy to say I’ve taken my shed ornament for a spin (finally) today! Now to sort out the tuning. Was nice to take it for a spin and take a break from getting the HectorSLAM / Cartographer stuff running for the RPLidarA2.

The map background is a custom image that shows tree locations in my orchard. Managed to only hit 2 while getting started tuning. Thanks for all of the tips you guys have developed over the year. Made a huge difference to getting it going roughly in a straight line :slight_smile:

Now, back to Cartographer!


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(Kenny Trussell) #148

That’s a nice looking machine. I like your actuator design. I have bought similar actuators but have not tried them yet. It took me a LOOOONG time to get my tuning acceptable and it still isn’t what I want, but the machine is very usable. Only hitting 2 trees is a good start! I look forward to seeing more!

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(Doug Wright) #149

Ben : That is nice work on the design. I want to get started with LIDAR in the future for collision avoidance. What are you using to implement LIDAR, ie controller?
Keep up the good work !

(Benjamin Neilson) #150

Continuing the discussion from Skid Steer Mower Overshooting pivot turns:

Cheers @ktrussell,

Yeah tuning is still a work in progress. I’ll take it next door to a neighbors big paddock. My place is all orchard.

Those actuators are off AliExpress from the GoMotorWorld shop, with potentiometer feedback. Seem to be working ok with the linear actuator controllers.

A bunch of little 5v relays are being controlled by electronic switches I bought. Those switch PWM output to on/off. Giving me solid control of ignition, start and pto.

I do like @Kevin_Groba ‘a Hitec actuators better. Think I’ll go that way in the future. A bit tidier.

Now for the SLAM system!


(Benjamin Neilson) #151

Cheers Doug,

Slowly coming along.

I’m essentially following the ArduPilot guide to setup RPLidarA2 with ROS, Cartographer slam, MavRos.

With any luck I’ll get the lidar data feeding back to the FCU via MavRos for proximity and collision avoidance.

A work in progress!

Good luck :+1:

(Kenny Trussell) #152

@BenBBB I have 2 of those exact actuators from GoMotorWorld. I have not installed them yet. Good to hear they are working OK. I believe there is plenty of room on my mower for them. It may be a while before I get to that.

(Benjamin Neilson) #153

Good luck when you get to them Kenny :+1:

(Kenny Trussell) #154

Ben @BenBBB ,
I finally connected the GoMotorWorld actuators tonight to my bench power supply. I am disappointed that at 12V it seems to be about 1/2 the speed they quoted. I have the model LA12S: 50mm stroke, 10mm/sec ( Very disappointing. It is no faster than the little Actuonix I have been using. I see on the vendor website, in answer to a question, that it can be run at 24VDC (and it does run twice as fast), but everything on the datasheet indicates it should be getting the specified speed at 12V. What model do you have and are you getting the speed you should?

(Benjamin Neilson) #155

Hey Kenny @ktrussell,
Glad to hear you’ve got the actuators going. Bummer to hear about the speed. I bought the 60mm/s 100mm stroke, 100N version. LA12Y. Controlling them with the Actuonix board. I haven’t measured the speed. My biggest issue has been slowing the steering down! Very happy with the rate of response from them for acceleration. The skid steering parameters are just taking a bit of tuning. Certainly finding it easier to drive a straight line between waypoints if I drop the mower’s speed. Other than that all is going pretty well. Bit of Ardurover side of things tuning to finish, but it goes so I’m spending my time working on the ROS side of things with the lidar and Cartographer. ( )

(Kenny Trussell) #156

Ben, I’m glad to hear the Actuonix controller will work with those actuators. I had planned to look compare the potentiometer specs of the two and maybe give it a try. Otherwise, I was going to do a DIY controller. I might try a step up voltage regulator module to get 24V and see how that works. I don’t know if the Actuonix controller will work with 24VDC but if not, I have an H-bridge controller that will.

The aliexpress link didn’t work for me in your last post, but it you are blazing a trail for me with the LIDAR and coprocessors and such!

By the way, on tuning, I found that the tuning parameters are very different for full engine RPM and lower RPM. The hydraulics just respond so much differently. I just do all my tuning at full RPM which is what I use for cutting.

(Benjamin Neilson) #157

Sorry, I’ll try that link again…

I’d certainly be happy to try a different controller. Certainly something more robust. Not sure how long they’ll take that current.

Yeah the mower is certainly much easier to drive straight at lower rpm. Tuning at high rpm has meant slowing skid steer turn parameters right down. Got to have a look at vibration affecting the IMUs as well. Seems to be having quite an effect on odometer measurements. That’s leading to poor localisation by the SLAM software. I might just try some rubber between my control box and the frame it’s bolted to, as well as the proper sticky pad (3M) that the Cube came with.

The goal is to get the SLAM stuff working well then developing a solid path planning algorithm to get my farm mowed :slight_smile:

(Kenny Trussell) #158

I noticed that when I have the mower blades running, I get a huge offset in the compass. I demonstrated in a video ( The new inflight compass calibration (Testers needed for in-flight compass learning) was a huge help.

(Benjamin Neilson) #159

Hey Kenny,
I’ll have a look at that in flight calibration. Pain in the ass taking everything apart! Coming along slowly but steadily. Not doing much on the Pixhawk side of things. Mostly mucking about with the SLAM system. THat’s a lot more like hard work :frowning:
Still, I’d certainly benefit from more tuning time on level ground with a decent GPS view. It’s on the to do list.

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(Bitdog LLC) #160


So I have gotten my mower out again this year and picked up where I left off. I have a full Reach RS+ base station going. The steering turning is coming along but my mower still overshoots its turns a bit. I want to add SLAM to the mower and I have been following the progress of others, most of which are indoor experiments. How are your outdoor experiences and have you integrated GPS with SLAM?