When designing a robot, one of the most important decisions is to choose the wheel. The wheels should be able to maintain the robot’s stability, help the robot handle various terrain, allow the robot to move quickly, and maintain navigation accuracy.
The larger the tire diameter, the faster the robot, but faster robot is not as strong as small tire robot. So when we design robots, we need to think carefully about our needs.
Knowing the circumference of a tire is important when considering what kind of tire and hub a robot needs to use. The circumference is the distance the robot travels in one revolution of the wheel, or, more simply, the length of the circle outside the wheel.
Now, what we have to know is that to calculate the circumference of the wheel we simply multiply the diameter of the tire by π (about 3.14) , so c = πd. You can place the wheel on a ruler to determine the diameter of the wheel and measure the widest distance outside the wheel. The diameters of many lego tires are marked on the side.
It is important to properly support the axle when mounting the wheels to the chassis. If the wheels are mounted close to the chassis, be sure to install an axle housing to ensure that the wheels are not pressed against the chassis. Also, if proper axle support can not be guaranteed, wheels should not be too far from the chassis.
Most robots use a cantilever assembly to attach the wheels to the chassis.
The image above shows the use of bushings to keep the wheels at the correct distance to prevent friction between the wheels and the chassis. This structure supports the axle only on one side, and because the axle is pressed against the chassis, there is friction on the axle.
The structure above uses multiple bushings, the wheels are farther away from the chassis, and there is more pressure between the axle and the chassis, so there is more friction between the two. In addition, this structure can cause the wheels to skew, resulting in unpredictable results when navigating. After a period of use, the axle itself begins to bend, making the robot’s performance even more unpredictable.
The most reliable solution is to build a chassis with support at both ends of the Axle, maximizing wheel and axle support and eliminating a lot of friction.
Now, we need to keep in mind that the chassis is important for proper support of the axle and wheels to ensure the robot’s reliability.
When people think of robots, they usually don’t think of wheeled robots, they think of tracked robots.
Tracked robots often require very low terrain heights, have a stable center of gravity, and can move quickly in small spaces, easily traversing rough and uneven ground.
While the tracked robot is cool and easy to build, it’s not always the best choice for a robot. When navigating, the tracked robot is inaccurate, making precise turns difficult, and even simple tasks such as walking straight on a flat surface can be affected. As the robot moves forward, the tracks jump, an additional challenge for the robot as it navigates the mission.
Today, we talked about how to choose the right wheels in the design of robot chassis. We hope it will be helpful for us to make robots. If we choose the right wheels, we can make a robot with stable running and accurate navigation.