This simple controller allow to setup rear servo on rc models with 4 steering wheels with only a cheap 2ch radio.

you can decide how fast throttle the 4 steering wheels will start to limit themselves and how wide the curve radius should be.

you can also decide to switch off the 4ws at maximum speed and have them at full width only at low speed and in reverse throttle.

this avoids tipping over at full throttle and having a great 4ws steering at low speed and reverse..

I also added blinking LEDs to indicate the steering direction.

setup is not too difficult and most of the instructions are written inside the code.

there are parameters to be defined which must be read with the serial monitor to know the right values of the radio control input signals. I wrote how to do it inside the code notes.

to build the controller you need 3-wire for servos, male and female plugs. it may be convenient to use a pair of Y-wires to pick up the throttle and steering signals without cutting esc or servo wires.

the setup becomes easy once you understand the configuration of your radio, I wrote what to do if the trottle or the steering is in reverse position.

this controller works very well, I mounted it on all of my trucks.

EXPANDED TECHNICAL DETAILS

Advanced RC Suspension Logic

This project upgrades a standard 2-channel RC car to a sophisticated 4-Wheel Steering (4WS) system using an Arduino Nano.

• PPM PWM Passthrough: The Arduino listens to the "Steering" signal from the RC receiver. It then calculates the required angles for TWO independent steering servos (Front and Rear).
• Steering Modes: Includes a toggle to switch between:
  • Normal mode: Rear wheels stay straight.
  • Contrary mode: Rear wheels turn opposite to front (extremely tight turning radius).
  • Crab mode: Rear wheels turn same as front (diagonal movement).

Racing Performance

• Proportional Mixing: The amount of rear-steering is automatically adjusted based on the speed of the car, providing stability at high speeds and agility at low speeds.