Large Rover With 4 Wheelchair Motors Design

Hello Forum!

I have accumulated 2 pairs of wheelchair motors, each pair of a different brand, however they seem close in output RPM. So what I want to do is make a large outdoor rover with these 4 motors for autonomous/RC driving over semi-rough terrain. I did a little bit of research and would have loved to do a rocker-bogie system but I can't afford 2 additional motors. So what kind of system would be ideal with 4 motors? would tank drive work with 4 motors or would car like steering be better? Also what kind of suspension if any would be well suited for this type of bot?

These are the max dimensions (space in my hatchback for transporting the bot :) ) 38" by 64" and 29" inches high I know inches are not used by all so here are centimeters 96cm by 162cm by 73cm high

This image should be to scale

In terms of construction it's doable but more difficult to include direction like a car. Since you have 4 motors it is better in my opinion to make use of each motor per wheel. But you could do a tank like system and have 4 different caterpilers one in each wheel and the direction working tank like.

Don't know what semi rough terrain is to you but i guess that way will do the deal. Try to build a suspention system like a rock crawler , you don't need to exagerate that much but put the body some space distant from the wheels / tracks .

What would the steering be like with a tank drive with 4 wheels? would the wheels be sliding/skidding when rotating?

The only easy to implement steering system that [u]doesn't[/u] skid is Ackermann steering.

As I lack experience with mechanics of this scale what would be advisable? how big of an issue would skidding be on a bot of this scale? Would Ackermann steering be a must for long life of motors and good performance?

In my opinion just do it tank like. You can even set levels of steering, imagine you have 3 leves , steering being controlled by a joystick.

example : turning left First level - 2 right motors go front , 2 left motors go back , fast turning second level - front wheel right side moves forward, left wheel back side moves backwards- third level - only back wheel right side moves forward , kind of slow turning.

since you have 4 independent wheels you have a lot of combinations you can choose.

Would Ackermann steering be a must for long life of motors and good performance?

Yes, and it doesn't tear up the floor or ground like a tank or other skid-steer mechanisms.