New to rc, need help / recommendations

Thread Starter

tonynsx

Joined May 5, 2020
3
I never made anything remote controlled before. I’m planning on making my riding lawnmower into remote controlled. I think I need something to turn the steering wheel, and something for brake and speed levers. I think for turning I can use something like a car windshield wiper motor with a motor controller? Also, I like to control this from inside my house.

Eventually, I like to add a micro controller to this project also. I’m familiar with Python, so may be an ESP8266 board will work for it. Any recommendations?

I think the first step is to make the lawnmower remote controlled. Please correct me if I'm wrong. I'm new to robotics.
 

dendad

Joined Feb 20, 2016
3,514
The first step would more likely be to start with a toy car, not a mower.
Get up to speed on a small one that is not able to cause damage first.
There are plenty of projects around to get help from, but starting with a mower as the first step is not the best way.
Most off the stuff you use for the small prototype can be moved onto the "real" one later after you debug the test one.

A quick search found this one..
https://makezine.com/projects/lawnbot400/
 
Last edited:

jpanhalt

Joined Jan 18, 2008
9,348
Are the steering and speed controls in your mower mechanical or hydraulic? Do you want to retain the ability to use it as a non-RC mower?

That is, if you are thinking of using a model airplane type servo to duplicate what you do while mowing, that may not be the best solution.
 

Thread Starter

tonynsx

Joined May 5, 2020
3
Are the steering and speed controls in your mower mechanical or hydraulic? Do you want to retain the ability to use it as a non-RC mower?

That is, if you are thinking of using a model airplane type servo to duplicate what you do while mowing, that may not be the best solution.
The steering and speed controls are mechanical. Steering is an actual steering wheel, but if I remove the steering wheel, I can attach a motor to the sprockets to turn it also. The speed control is a lever that slides up and down.

I like to drive it myself also when not using in RC mode, that's why I'm planning on connecting stuff to the steering wheel, speed control etc.

What type of servo do I need? Also, I need to be able to control this from inside my house (if that's possible)
 

jpanhalt

Joined Jan 18, 2008
9,348
Operation voltage
Current
Speed to reach a set position
Range of motion
Torque

Those are the major characteristics to consider. Error for repeatable positions, dead-band (amount of change in signal before the servo responds) are two other. Everythong I say is with respect to model servos, not commercial servos.

With mechanical steering, you will need a pretty strong servo. You will also need a way to disconnect the servo when it is not being used. Even without power, most servos will have resistance from the gears and from turning the armature in a magnetic field. There are three types: brushed, coreless, and brushless. The brushed versions use a typical DC motor. Coreless motors get rid of the steel plates in the armature, and brushless don't use mechanical brushes for commutation. The prices are in that same order with brushed being cheapest and brushless being the most expensive.

In my experience, coreless are a little easier to move when there is no power. I have minimal experience with brushless servos. In your case, I do not think you can or should rely on moving the servos when power is not applied. In other words, I think you will need a mechanical disconnect.

For powerful coreless and brushless servos cost can get pretty high. So, my advice would be a brushed conventional servo. You might be able to find something that will operate that 12 V, assuming you mower is a 12 V electric start.

Of the 5 characteristics, the one of most importance in your application is torque. Any servo having sufficient torque at your chosen voltage will have sufficient speed and range of motion.
 

danadak

Joined Mar 10, 2018
4,057
Yes a server-client link made out of ESP8266 or ESP32 would be a straight forward way of
doing the RF link. The only disadvantage to these parts is support by manufactures poor.
But that being said there is a lot of forums out there targeted to using these parts.

Be aware of distance limitations, you can google this to see what others have achieved. If
yard adjacent to house I think there will be no problem. Just select channel number by
looking at spectrum in your area to minimize COM interference.

The other issue is the A/D on the 8266 is poor accuracy, just be aware of that. Users have
resorted to averaging to get the ENOB up. I think the ESP32 being newer has a better A/D in it,
however not had a chance to examine datasheet on that.

Lastly you will be controlling some large current / inductive loads. Power management
and layout crucial to success (so your ESP chip is not randomly resetting or vectoring off
into program outer space. And the safety issues are significant, no need to be losing
control and running over babies. So code considerations, even consider using a dual core
so that the cores keep an eye on each other to make sure one has not gone nuts. NASA
i think has a lot of online papers on this topic.. There are chips out there to do dual core.


Regards, Dana.
 
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