I am working on a high speed autonomous robot (about 6-7 m/s), which does obstacle detection as well as senses traffic lights (I have used Raspberry Pi 3 and Arduino Uno).

For the steering mechanism, I wanted to implement an Ackerman's steering. I've read about the principle and have understood its basics. Now to actually make the design, I am currently using switchboards, sold here in India, they are surprisingly strong, lightweight, waterproof(they are switchboards) and cheap. Now I got 1 big axle and the small axle cut out already, along with the two L-shaped pieces that join the 2 axles together... I'm just now confused as to how to connect the wheels to the axle and how to make them rotate along side it. The site won't let me upload any pics right now, I'll try again ASAP.

I have the switchboard, an electric drill and will to do anything to make this happen ( ;P ). I don't have access to a 3D Printer.

Any help would be greatly appreciated...

P.S- And if you have any suggestions of your own, which might be better for my robot, feel free to share them, I'm just looking for a good steering method for my robot.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – Mark Booth May 5 '16 at 15:21

The key device for Ackermann steering is the steering knuckle. It has two vertical mount and an arm with a third mount.

The upper and lower control arms attach the vertical mounts to the frame of the vehicle - this lets the wheel move up and down. This may or may not be more complicated than you need, as the control arms are what enable suspension. The strut generally attaches to or replaces the upper control arm.

The arm on the steering knuckle allows a tie rod to be attached. The arm is at an angle to the face of the steering knuckle, and that angle is determined by the wheel base and width of the car. From the Wikipedia page on Ackermann steering:

[Ackermann steering] was achieved by making the linkage not a simple parallelogram, but by making the length of the track rod (the moving link between the hubs) shorter than that of the axle, so that the steering arms of the hubs appeared to "toe out".

If you actually had one solid rod between the two tires, it would bend the first time the suspension moved. Instead, the steering gear box is bolted to the frame, and then tie rods attach the steering knuckle to the gear box.

At each end of the tie rod is a "tie rod end" or rod end, which has a spherical bearing and allows the tie rod to move with suspension travel.

So, tl;dr - Ackermann steering is actually a relatively involved setup, especially if you can't source properly sized components. This is why a lot of small and medium sized robots use differential steering and caster wheels.

  • 1
    $\begingroup$ Thanks Chuck, this is a valiant attempt to answer a very difficult to answer question. $\endgroup$ – Mark Booth May 2 '16 at 15:28

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