Electric motor working principles: How do electric motors work?
Electric motors work based on the principle of electromagnetic induction. A current carrying coil is placed between a permanent magnet of the north and south pole. When an electric current is passed through the coil, a magnetic field is generated by the coil based on the direction of the current. This causes the two arms of the coil to repel away from the permanent magnet by causing a rotational motion. Once the coil reaches halfway, the direction the current is switched and the process repeats again, thereby causing a fast rotational motion. The direction of the force, current and magnetic field can be determined by Fleming’s Left Hand Rule.
How do I choose a motor for a robotics project?
The type of motor to choose for a particular project depends on the application and the use case of the motor.
DC motors - Suitable for application where the motor just needs to spin up and/or down fast.
Stepper motors - Used in cases where more precision of motor movement is required.
Servo motors - Used in applications where absolute precision and angle of the motor is of highest importance.
Are Servo motors AC or DC?
Servo motors come in both AC and DC types, although DC is more commonly used. DC servo motors work on the basis of a feedback loop where the angle of the motor shaft is measured by an encoder, so the embedded microcontroller can give the correcting signal to the motor,
What are the most common types of electric motors?
BO motors are just a colloquial term for a DC motor that are used in applications such as robotics
The DC motor is a device that transforms electrical energy into mechanical energy in form of rotation. It works based on the principle of electromagnetism. DC motors have inductors inside, which produce the magnetic field used to generate movement.
A stepper motor is a brushless DC electric motor that divides a full rotation into a number of equal steps. They have multiple coils organized inside along the stator and periodic excitation of the coils causes the rotor to align, hence simulating steps.
A servomotor is a rotary actuator that allows for precise control of angular or linear position and velocity. It makes use of a DC motor, gears, encoder and a tiny microcontroller to form a servo motor. It follows the mechanism of negative feedback loop to achieve great precision in the position and angles of the motor shaft
What are the different ways of using motors in a robotics project?
DC motors can be used to run wheels on any mobile based robots.
Stepper motors are used in applications like robotic arms, where arm’s positional accuracy and stepper motor’s energized stall is required.
Servo motors are used in applications where precise angular output is desired by the user, like steering wheel in self driving cars, etc.
Frequently asked questions about DC Motor
How to choose a DC Motor for a robot?
DC motors for a robot must be chosen based:
- Torque characteristic
- Load characteristic
- Power consumption
Robot needs to be equipped with adequate suitable DC motors which are capable of driving the bot comfortably and allow the max weight expected while also trying to keep power consumption as low as possible
How to make a robotics arm using a motor?
Robotic arms require precise movements of joints in different directions with minimal to no error, while remaining flexible as much as possible. Therefore stepper motor is ideal for this particular use case, as it takes accurate steps with no increase in error with each graduation. Stepper motors generally also have more torque and can rotate full 360 degrees unlike many low cost servo motors.
If the robotic arm is required to be very precise, then industrial grade servo motors are used since it offers really good precision and accuracy.