By UselessPickles - Fri Apr 01, 2011 11:13 pm
- Fri Apr 01, 2011 11:13 pm
#15446
My son received one of the Kawasaki ATV Power Wheels for his birthday and I was quite disappointed with the following:
I decided to solve all of this by adapting it to use a speed controller for an RC car (a.k.a. "ESC", for Electronic Speed Controller). Some of them are very configurable for things such as "punch control" (smooths out twitchy throttle transitions) and torque limiting (to protect the gear boxes), among other things. Some even have regenerative braking and anti-lock braking. The torque limiting would be especially useful because it could allow me to use fast and powerful motors to get higher speeds without straining the gears with too much acceleration.
My plan is to modify the throttle tube to rotate more (about 1/8 of a full rotation) and link it up to a slide potentiometer. I'll also link up the pedal to a slide potentiometer. I'm a programmer and have a friend that knows electronics and how to program microcontrollers, so we will work together to create a custom circuit that converts the potentiometer positions into a single throttle servo signal, as expected by the ESC.
The throttle on the handle bars will be forward throttle and the pedal will be braking and reverse. ESCs treat reverse throttle as braking if the motor is currently spinning forward, and will not go into reverse until the motor has come to a complete stop. They can also often be configured to require that the throttle is returned to neutral for a second or two after stopping before re-applying reverse throttle to go in reverse.
Once I have the custom electronics and physical modifications complete, I will be able to remove the entire wiring system of the Power Wheels and replace it with any ESC of my choosing. I'll start by keeping the stock motors, but could easily use a high-voltage capable ESC, brushless motors, etc. I'll also be able to use lithium polymer batteries (a.k.a. "lipo" - light weight, small, can be charged faster, maintain voltage under amp draw better, etc). The ESC has built-in low voltage cut-off to protect lipo batteries from over-discharging. You can't use lipos without low voltage cut-off, because if you run a lipo down until you notice it's slowing down, the damage has already been done.
I'll post updates and pictures to this thread as I make progress
- What would normally be a brake pedal on motorcycles is actually the primary throttle of this Power Wheels.
- The throttle on the handle bars is only used to activate "high speed" mode (only if the pedal is also pressed; does nothing otherwise).
- The throttle isn't proportional! Just on or off. It's very twitchy, and it actually scared my kid.
I decided to solve all of this by adapting it to use a speed controller for an RC car (a.k.a. "ESC", for Electronic Speed Controller). Some of them are very configurable for things such as "punch control" (smooths out twitchy throttle transitions) and torque limiting (to protect the gear boxes), among other things. Some even have regenerative braking and anti-lock braking. The torque limiting would be especially useful because it could allow me to use fast and powerful motors to get higher speeds without straining the gears with too much acceleration.
My plan is to modify the throttle tube to rotate more (about 1/8 of a full rotation) and link it up to a slide potentiometer. I'll also link up the pedal to a slide potentiometer. I'm a programmer and have a friend that knows electronics and how to program microcontrollers, so we will work together to create a custom circuit that converts the potentiometer positions into a single throttle servo signal, as expected by the ESC.
The throttle on the handle bars will be forward throttle and the pedal will be braking and reverse. ESCs treat reverse throttle as braking if the motor is currently spinning forward, and will not go into reverse until the motor has come to a complete stop. They can also often be configured to require that the throttle is returned to neutral for a second or two after stopping before re-applying reverse throttle to go in reverse.
Once I have the custom electronics and physical modifications complete, I will be able to remove the entire wiring system of the Power Wheels and replace it with any ESC of my choosing. I'll start by keeping the stock motors, but could easily use a high-voltage capable ESC, brushless motors, etc. I'll also be able to use lithium polymer batteries (a.k.a. "lipo" - light weight, small, can be charged faster, maintain voltage under amp draw better, etc). The ESC has built-in low voltage cut-off to protect lipo batteries from over-discharging. You can't use lipos without low voltage cut-off, because if you run a lipo down until you notice it's slowing down, the damage has already been done.
I'll post updates and pictures to this thread as I make progress

Last edited by UselessPickles on Fri Apr 29, 2011 5:17 pm, edited 3 times in total.