DIY Radio Controlled Lawnmower

– ELECTRONICS –

 

A TRUE DO-IT-YOURSELF Radio Controlled Lawn Mower!

all material here is copyright Terry Creer 2007

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DISCLAIMER - THE METHODS OF CONTROLLING AN UNMANNED VEHICLE DETAILLED BELOW ARE POTENTIALLY LETHAL. YOU CAN KILL SOMEONE, AN ANIMAL OR A ROSE GARDEN IF YOU ARE NOT CAREFUL. I ACCEPT NO RESPOSIBILITY FOR LOSS OF LIFE, BEER PRIVELEGES OR SEX FOR CONSEQUENCES THAT ARE BEYOND MY CONTROL. IF YOU DECIDE TO BUILD A MOWER LIKE MINE YOU DO SO AT YOUR OWN RISK. BY BUILDING THE PROJECTS STATED BELOW YOU ARE ACKNOWLEDGING THAT IT IS ONLY YOUR FAULT IF SOMETHING GOES WRONG.

 

Introduction (What is it???)

 

Ok, so what are these doohickeys I'm trying to explain below? As explained in the Project Introduction, basically we have a wheelchair with a lawnmower strapped under it.  The big question is - "how do I control it from my back porch?"

The circuits below replace the actual joystick that's plugged into the wheelchair controller.  They are an interface between the Radio Receiver and the Chair controller. They take the signals from the Radio Control Receiver and translate them into the language that the Wheelchair controller understands (i.e. the joystick signals).

Therefore, the wheelchair controller 'thinks' the joystick is still there and someone is sitting in the chair moving it, but they are actually across the yard with the transmitter and a beer.

 

Hardware (Electrickery)

Basically, there’s a couple of different options to do the RC to Joystick interface – the easy way and the hard way.

Below is a brief summary of each and also weighs up the Pros and Cons to help decide which is best for you…

 

OPTION 1 - The Simple Approach

Summary:

A simple Hobby Store-based replacement for the joystick on the wheelchair controller.

It requires a couple of readily available components from an electronic supply store (approx $5AUD worth) but nothing scary. a little soldering is also required but nothing fiddly.

Pros:

-         Great for those with little electronics knowledge

-         Simple and relatively inexpensive (most parts are included when you buy a hobby transmitter pack).

-         Parts are readily available from local hobby store and electronics outlet

-         My mum could build it (no offence mum :P)

Cons:

-         Requires bulky external box to mount everything in (highly recommended for enviromental protection).

-         Requires separate battery pack/power supply for receiver and servos (Servo's are too noisy for the joystick supply).

-         Requires 1 (or even 2) external hobby failsafes (not 100% necessary, but HIGHLY RECOMMENDED for a potential ROBOT KILLING MACHINE!).

-         Fiddly to set up due to the mechanical components.

CLICK HERE FOR INFORMATION ON HOW TO BUILD THIS INTERFACE

 

 

OPTION 2 - The Not-So-Simple Approach

Summary:

A more advanced controller which emulates the joystick's signals using no mechanical parts at all.

I designed this version for three main reasons:

1.      It uses far less power than the 'cheap n simple' version (hence requires no external power supply)

2.      It has no moving mechanical parts (all solid-state electronics)

3.      Finally, the whole controller and radio control receiver fits inside (and is powered) by my wheelchair controller box. Note, however, it may not fit in the one you choose.

I've tried to keep it as simple as possible to make it accessible to the home hobbyist. I intend to supply PCBs to those who are interested for a small fee.

Pros:

-         no servos, no battery pack and no pots required (therefore, no moving parts)

-         low power consumption - feeds on power from the joystick's internal power supply

-         no external box for mounting required - fits in original wheelchair controller box

-         built in fail-safes

-         easiest to install

Cons:

-         requires some electonics knowledge and soldering (unless bought as a pre-built kit)

-         may be difficult to get parts if DIY'ing it

CLICK HERE FOR INFORMATION ON HOW TO BUILD THIS INTERFACE