Guide

1 lb.
5 lbs.
10 lbs.
Mechanisms: DC Motors (Grades 4-8)
Actuators are used to act upon an environment, usually for moving or controlling a mechanism
or system. Actuators drive everything that moves on a mobile robot. The most common type of
actuator is a motor; in particular, VEX IQ utilizes Direct Current (DC) Motors.
DC Motors convert electrical energy into mechanical energy through the use of electromagnetic
elds and rotating wire coils. When a voltage is applied to a motor, it outputs a xed amount of
mechanical power (usually to a shaft, gear, and/or wheel), spinning at some speed with some
amount of torque.
Motor Loading
Motors apply torque in response to loading. Motor
Loading happens when there is any opposing
force (such as friction or a heavy mass) acting as
a load and requiring the motor to output torque to
overcome it. The higher the load placed on a motor
output, the more the motor will “ght back” with
an opposing torque. However, as you learned in
the Key Concepts Unit, since the motor outputs a
xed amount of power, the more torque the motor
outputs, the slower its rotational speed.
If you keep increasing the load on a motor it
eventually stops spinning or stalls.
Current Draw
A DC Motor draws a certain amount of electrical
current (measured in amps) depending on how
much load is placed on it. As the load increases on the motor, the more torque the motor
outputs to overcome it and the more current the motor draws.
G.2
Motor applies torque to overcome friction
of a wheel turning against the ground.