If make RC model project, we will use the mini motor. So how to choose the correct mini motor is very important.
The three kinds mini motors are often used for the RC model: DC Motor, Stepper Motor, and Servo Motor.
DC motor: It's used for drive the the robots movements. If connect power, the motor will continue working. If change the "+/-", the motor rotator direction will be changed. The DC motor price is low, very suitable for the most application.
Mini DC Motor Mini DC Gear Motor
Stepper Motor: It's a kind of DC motor, that can divide a full rotation into a large number of steps. The motor's position can be controlled precisely without any feedback mechanism (an open-loop controller), as long as the motor is carefully sized to the application.
Switched reluctance motors are very large stepping motors with a reduced pole count, and generally are closed-loop commutated.
The Stepper motor is often used for the robot arm.
Servo Motor: A servomotor is a motor which forms part of a servomechanism. The servomotor is paired with some type of encoder to provide position/speed feedback. A stepper motor is one type of servomotor. A stepper motor is actually built to move angular positions based upon each possible step around the entire rotation, and may include micro-steps with a resolution such as 256 micro-steps per step of the stepper motor. A servomechanism may or may not use a servomotor. For example, a household furnace controlled by a thermostat is a servomechanism, because of the feedback and resulting error signal, yet there is no motor being controlled directly by the servomechanism.
The servo Motor is often used for the robot head, arm, and foot.
Mini Motor Specification:
Voltage: Normally the mini motor for small robots voltage is 1.5V-6V. The higher voltage, the higher speed. Sometimes also use the rated voltage 12V or 24V. The motor can work under the lower voltage, for example, the 12V motor can work under 8V voltage, but the speed will lower and torque will reduce. If motor long time woking under higher voltage (higher 30%-40% rated voltage), the motor will be hot, it's easy damged.
Current: The current have no-load current and load current. The load current is the real working current. If load reach the max, the motor will stop, the current will not increase.
Speed: the unit is r/min, the robots often need the motor speed is 100-200rpm, or lower. But the DC motor speed range is 4000-7000rpm, so it need lower the speed. You can add the gearbox to change the speed ratio.
Torque: torque is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist. The unit is g/cm.