Table of Contents
Tank drive refers to a specific control style where two parallel forces of motion are controlled to create linear and rotational motion. The mechanical system can be composed of tank tread, or any number of wheels, all facing the same direction with two independently controlled “sides”. In a tank drive system, motion is controlled by the relative speed of the two “sides”.
Advantages to this drive system include:
- High traction to the field. It is very difficult to push a tank drive robot in a direction it does not want to go.
- Generally compact. It is easier to fit more wheels, motors, and gears into less space with this type of design than one in which wheels are at angles.
- Very simple to program. Tank drive is easy to fit to almost any control scheme and is an excellent place to start learning.
Disadvantages to this drive system include:
- Difficulty turning. The high traction resists pushing but also resists turning. Special tank drive systems to avoid this are below.
- Unreliable position mapping. Due to the nature of turning by sliding, it can be difficult to accurately predict turns via motor revolutions.
- Omni Wheel Tank Drive - This is a drive system where all wheels are omni wheels, allowing easier turning, but making the robot susceptible to pushing.
- Drop Center Tank Drive - This system raises the front and back wheels a certain amount higher than the center wheels, allowing the robot to tip back and forth between different pairs. This lowers the turning resistance while maintaining the desirable tipping prevention of a long base, but it also makes tracking even more difficult, as it can be difficult to predict what pair of wheels you may be on when you turn.
- Hybrid Tank Drive - This system combines aspects of both of the above, by utilizing standard wheels in one location and omni wheels in the rest. This allows the robot to turn easily and reliably around the center of the standard wheels.