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Remote Control Lawn Mower

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reddog

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Remote Control Lawn Mower

by reddog » Sun Apr 12, 2015 10:40 am

I have been making a remote control lawn mower for quite some time now and I am finally close to finishing it.

Its running a Honda GSV 190 4 stroke engine for cutting the grass and running the alternator.
2 x 350w wheelchair motors
Alternator rewound for high amperage, 24 volt operation.
Dimension Engineering Sabertooth 2x60.

I am using a CopterControl (not CC3D) as the brain. Its configured for differential steering with AxisLock on Yaw (the steering channel). I am using a single flight mode.

TauLabs has a requirement for 4 inputs (throttle, roll, yaw, pitch) plus arming switch (if in use) I am controlling this vehicle with a 3 channel transmitter. The transmitter only outputs throttle and yaw plus arming, so I had to work out a way of having the CopterControl see roll and pitch. Pug398 came up with an option that worked well, putting a splitter on the two outputs on the receiver and connecting them to roll and pitch - viewtopic.php?f=6&p=5347#p5312

I have only 2 issues now.

1. When disarmed the mowers run backwards at full speed. It seems when disarmed TauLabs outputs a PWM value of 1000 (full backwards in my case). I am not sure why it doesn't output the neutral value configured on the Output tab.
2. It seems that I am having trouble with stabilisation. When AxisLock or Rate are enabled on yaw, one motor slowly moves forwards while the other doesn't move at all. When turning the steering wheel (yaw) on the transmitter the only thing that happens is the one motor which moves will stop when I am at full throw but the other motor does not move at all. When I switch to manual everything works perfectly.
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Re: Remote Control Lawn Mower

by pug398 » Sun Apr 12, 2015 6:11 pm

Robotic lawnmower. Cool stuff!

For the neutral type output you are looking for I believe you need to go into the settings>mixer and set the mixer output channel for servo instead of motor. Motor neutral stop is usually 1000us where a servo neutral stop is ~1500.

You would have to run a lot of I term to keep it on track but that does not sound exactly like your second problem. It does not have any yaw stabilization at all? It could be related to problem #1 since you are using it in servo mode application not motor drive mode.
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Re: Remote Control Lawn Mower

by reddog » Sun Apr 12, 2015 10:16 pm

pug398 wrote:Robotic lawnmower. Cool stuff!

For the neutral type output you are looking for I believe you need to go into the settings>mixer and set the mixer output channel for servo instead of motor. Motor neutral stop is usually 1000us where a servo neutral stop is ~1500.


I will do this, thanks again!

Is there any reason to have a motor and a servo behave differently? I cannot see a reason why you would want a motor to behave differently, especially since the zero point (or neutral setting) of the output (servo/motor) is already available to the system.
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Re: Remote Control Lawn Mower

by reddog » Sun Apr 12, 2015 10:20 pm

pug398 wrote:It does not have any yaw stabilization at all?


It seems like stabilisation is not working as you would expect, almost like stabilisation is working on the incorrect axis.

pug398 wrote:It could be related to problem #1 since you are using it in servo mode application not motor drive mode.


Both outputs are configured as motor outputs.
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Re: Remote Control Lawn Mower

by reddog » Sun Apr 12, 2015 10:22 pm

pug398 wrote:Robotic lawnmower. Cool stuff!

For the neutral type output you are looking for I believe you need to go into the settings>mixer and set the mixer output channel for servo instead of motor. Motor neutral stop is usually 1000us where a servo neutral stop is ~1500.


Will changing the outputs from Motor to Servo change any safety features in the software. The only problem with the arming switch is there is no way to know if it is on or off when starting up the vehicle. This is something I need to solve either in the TauLabs software or on the transmitter.

Is there any reason to have a motor and a servo behave differently? I cannot see a reason why you would want a motor to behave differently, especially since the zero point (or neutral setting) of the output (servo/motor) is already available to the system.
Last edited by reddog on Mon Apr 13, 2015 11:02 am, edited 1 time in total.
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Re: Remote Control Lawn Mower

by pug398 » Sun Apr 12, 2015 11:15 pm

If your motor driver has forward/reverse and is setup to take rc input then it is looking for 1500uS (stop), >1500uS (forward) and <1500uS reverse. With your current configuration (mixer-motor output) when you disarm the output goes to low endpoint which for you is full reverse. You need to set it for servo output on both drive channels and then set the neutral slider to whatever point stops the motors (~1500uS). For motor output it goes to low endpoint on disarm. For servo output it goes to whatever the slider is set to. It use to be that way early on and don't think it has changed but not positive.
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Re: Remote Control Lawn Mower

by reddog » Mon Apr 13, 2015 11:01 am

pug398 wrote:If your motor driver has forward/reverse and is setup to take rc input then it is looking for 1500uS (stop), >1500uS (forward) and <1500uS reverse. With your current configuration (mixer-motor output) when you disarm the output goes to low endpoint which for you is full reverse. You need to set it for servo output on both drive channels and then set the neutral slider to whatever point stops the motors (~1500uS). For motor output it goes to low endpoint on disarm. For servo output it goes to whatever the slider is set to. It use to be that way early on and don't think it has changed but not positive.


Thanks pug398. I understand what you are recommending but I am not that keen to implement it. This is not a small mower, it weighs more than 60kg and spins 4 x 21 inch blades. By setting my motors as servos the mower will never be disarmed as TauLabs does not disarm servos.
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Re: Remote Control Lawn Mower

by pug398 » Mon Apr 13, 2015 1:18 pm

Yes it was evident from the start it is a dangerous project :)
With the servos outputs arming once and then never disarming until reboot I would not recommend you using it either. Perhaps someone else knows a different way to set it up.

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