The difference between ordinary motor, geared motor, stepper motor, servo motor

In this article, ordinary motors, stepper motors, and servo motors refer to DC micro motors, and the ones that we usually come into contact with are also DC motors.

Electric motor, also known as "motor", refers to this kind of electromagnetic induction device that maintains the transformation or transmission of electromagnetic energy according to the law of electromagnetic induction. The motor is also called (alias motor), and the English letter "M" ("D" in the old standard) is used in conjunction with the power circuit to express. Its main function is to generate driving torque, which is used as a power source for electrical appliances or various machines. The generator is represented by the letter "G" in the circuit.

Ordinary DC motor

Ordinary motors are the ones we usually have. There are electric toys, razors, etc. inside. Generally, there are only two wires, so if the positive and negative wires of the battery are connected and then rotated, the motor that connects the positive and negative wires of the battery will also reverse. The characteristic of this motor is that the speed is too fast and the torque is too small, so it is generally not used in smart cars.

Reducer Motor

The so-called reducer refers to the addition of a reducer to the ordinary motor to reduce the speed and increase the torque, so that the ordinary motor has a broad space for use.

Smart car chassis

The reducer is generally mounted on the smart car, and the motor control generally adopts the h-bridge method, and the L298 chip is its principle. On the other hand, the speed regulation generally adopts PWM (Pulse Width Modulation) mechanism. The single-chip microcomputer generates PWM waves with variable duty ratios through timer control, or directly generates hardware PWM output waveforms of different sizes to control the overall speed of the trolley.

Stepper motor

Stepping motor is an open-loop control unit stepping motor component that converts electrical pulse signals into angular displacement and linear displacement. When it is not overloaded, the motor's speed and stop position only depend on the frequency and pulse number of the pulse signal. When the stepper driver receives the pulse signal, driving the stepper motor to rotate at a certain angle to the set direction is called " Step angle", which rotates further at a certain angle. By controlling the number of pulses, the angular displacement can be controlled to achieve correct positioning. At the same time, by controlling the pulse frequency, the rotation speed and acceleration of the motor can be controlled to achieve the purpose of speed regulation.

Steering gear and servo motor

The steering gear is mainly composed of a housing, a circuit board, a coreless motor, a gear and a position detector. Send a signal from the receiver to the steering gear, determine the direction of rotation through the IC on the circuit board, rotate the coreless motor, transmit power to the swing arm through the reduction gear, and return a signal from the position detector to determine whether the positioning is achieved. The position detector is actually a variable resistor, and the resistance value changes when the steering gear rotates, and the rotation angle can be known by detecting the resistance value. The steering gear specifications and materials presented by the manufacturer all include basic information such as size (mm), torque (kg/cm), speed (seconds/60°), detection working voltage (V) and net weight (g). The unit of torque is kg/cm, which means that a few kilograms of objects can be hung at the arm length of 1 cm. This is the concept of a force arm, so the longer the swing arm length, the smaller the torque. The speed unit is second/60, which means the time required for the steering gear to rotate 60°.

Servo motors are also called drive motors, which act as drivers in automatic control systems, converting received electrical signals into angular displacement and angular velocity output on the motor shaft. Divided into two major categories of DC and AC servo motors, its main feature is that there is no rotation when the signal voltage is zero, and the speed decreases at the same speed as the torque increases.

It can be understood that the servo is mainly positioned by pulses. Basically, when the servo motor receives 1 pulse, it only rotates the angle corresponding to 1 pulse for displacement. Because the servo motor itself has the function of sending pulses, the corresponding number of pulses can be sent out by the servo motor every rotation angle, which can correspond to the pulses received by the servo motor, or called a closed loop, and the system can know how many pulses are sent to the servo motor , Receive several pulses to return at the same time, correctly control the rotation of the motor, and realize the correct positioning, which can reach 0.001mm.

DC servo motors are divided into brushed and DC brushless motors. Brushless motors are low-cost, simple in structure, large starting torque, wide speed range, very easy to operate, and must be maintained, but the maintenance is not convenient (changing the motor carbon brush), causing interference signals, and there are regulations on the natural environment. Therefore, it can be used in general industrial production and civilian-use places that are more sensitive to costs.