Servo - December 2013

All robot components rely on a mobile robot’s base; a good design need not be complex. I wrote an article for SERVO discussing robot mobility about four years ago, however, some new and affordable ready-made robot bases have come on the market that I would like to discuss, as well as offer some construction tips. I’ll discuss what I believe are some important facts to consider, but you can always go to the Internet for more information. I’m not going to cover aerial or underwater vehicles as these categories have their own special design considerations.

Design Issues to Contemplate

Quite a few configurations and wheel arrangements are utilized in mobile robots. The two most popular wheel/steering configurations used in mobile robot bases are Ackermann steering and differential steering.

Ackermann steering is what is called automobile type steering — two wheels in the front (or back) that steer right or left in order to change the direction of the vehicle. I will discuss this type more thoroughly later as it is not as common for mobile robots.

Robot bases and their required structure are very critical parts of mobile robot design. In most cases, these vital components allow the robot to perform more complex functions such as exploring its environment. I know of many great robot builders who can write bug-proof code in their sleep but literally cringe at the task of designing a base and structure for their mobile robot. Cutting out base parts, mounting motors, and laying out sensor locations frightens many people, but these parts can be made with basic tools. You can cut sheet stock to fabricate a robot base or structure, or you can actually construct a base from beams and parts such as the articulated robot base shown in Figure 1 built with ActoBotics™ components.