Understanding Robot Speed Calculations

When designing a mobile robot, one of the most critical specifications is its theoretical top speed. Whether you are building a competitive combat robot, a warehouse AMR (Autonomous Mobile Robot), or a simple hobbyist rover, knowing how fast your machine will travel is essential for path planning and motor selection.

The Robot Speed Calculator uses three primary variables: Motor RPM, Gear Reduction Ratio, and Wheel Diameter. The relationship is straightforward: the motor provides the rotational speed, the gearbox adjusts that speed for torque, and the wheel diameter determines how much distance is covered in a single rotation.

How to Use the Robot Speed Calculator

To get an accurate measurement, follow these steps:

• Motor RPM: Enter the Revolutions Per Minute of your motor at its rated voltage. Use the "No-Load RPM" for theoretical max or "Rated RPM" for a more realistic estimate.
• Gear Ratio: Enter the reduction ratio. For example, if you have a 10:1 gearbox, enter 10. If the motor is direct drive, enter 1.
• Wheel Diameter: Measure the outer diameter of your drive wheels. Ensure you select the correct unit (mm, cm, or inches).

Important Factors for Real-World Speed

It is important to note that this tool provides the theoretical maximum speed. In real-world applications, several factors can reduce this speed by 10% to 20%:

1. Battery Voltage Sag: As batteries discharge, their voltage drops, leading to lower RPM.
2. Friction and Load: The weight of the robot and the friction in the bearings and drivetrain create drag.
3. Tire Slip: On smooth surfaces, wheels may slip, meaning the robot travels less distance than calculated.