During the selection phase of robot hub motors, many customers ask about the maximum speed in km/h or m/s, but we only have the motor’s rotational speed (expressed in RPM). So how do we calculate the linear velocity based on the motor’s size and rotational speed?
The following are the basic steps for calculating linear velocity:
1. Determine the motor speed: Assume the motor speed is N, in RPM (revolutions per minute).
2. Determine the dimensions of the motor: Assume the rotor diameter of the motor is D, in millimeters (mm).
3. Calculate the circumference: The circumference C of the motor rotor can be calculated using the formula:
C = 0.001πD, unit: meters (m).
4. Calculate linear velocity: Linear velocity V (unit: m/s) and v (unit: km/h) can be calculated using the following formulas:
V = NC/60 = 0.001ΠDN/60, unit: meters per second (m/s)
v = V * 3.6 = 0.00006ΠDN, unit: kilometers per hour (km/h)
Let’s illustrate with an example:
Assume the motor speed is 100 RPM and the hub motor diameter is 200mm.
1. Calculate the perimeter:
C=0.001πD=0.628m,
2. Calculate the linear velocity:
V = NC/60 = 0.001ΠDN/60 = 1.047 m/s
v = V * 3.6 = 0.00006πDN = 3.77 km/h
Additionally, it should be noted that the above calculations assume the motor rotor is an ideal circular object; in practical applications, factors such as friction and load may affect the calculation. If the motor drives other mechanical components through gears, belts, or other transmission devices, the linear velocity calculation may need to consider factors such as the transmission ratio.
Post time: May-19-2026