What Is The Difference Between A Motor And A Steering Gear? Mixing Up The Equipment May Cause It To Malfunction

Recently, several friends who make smart cars came to talk to me, saying that the motor rotates very happily during debugging, but gets stuck after installing theservo, or vice versa. In fact, many people have suffered losses from the two brothers "motor" and "steering gear". They look similar, but if used in the wrong place, the efficiency will be low at best, or the equipment will directly stop working. Today we will break it down and understand the difference between these two things and how you should choose.

The motor only needs to turn the steering gear and be obedient.

To put it bluntly, Motor is a "brute force player". If you energize it, it will rotate. It will rotate as fast as you give it voltage, and it doesn't care which position it rotates to. It only does one thing: spin. For example, small fans and wheels only need to be rotated, and there is no need to know where to stop. At this time, it is most suitable to use a motor.

The steering gear is different, it is an "obedient player". You tell it "turn to 90 degrees", and it will turn to 90 degrees and stop. It also has feedback to know whether it is in place. For example, robot joints and camera gimbals need to control the angle accurately, so you have to useservos. In addition to the motor, it also has a set of control circuits and position sensors.

The control methods are very different. One directly gives instructions to the other.

Using the motor is particularly simple and crude. A DC motor will rotate if you connect the battery to it, and reverse if you connect it reversely. Want to speed things up? Just use the PWM signal, that is, adjust the frequency of the voltage on and off, and the speed will be determined. You don't even need a microcontroller, just build an H-bridge with a few transistors, and the threshold is very low.

There are a lot of details involved in steering gear control. It usually uses three wires, namely power, ground and signal wires. You need to provide it with a pulse with a period of about 20 milliseconds, and the width of this pulse is between 0.5 and 2.5 milliseconds, so that it can correspond to the angle range of 0 to 180 degrees. Moreover, you must use a microcontroller or a specialservocontrol board to send signals so that the servo can move. So, if you are not particularly familiar with programming, there is still a certain threshold for playing with servos.

In actual operation of steering gear control, the details are quite critical. Of those three wires, the power supply is responsible for providing power, the ground wire ensures the stability of the circuit, and the signal wire transmits key instructions. The given pulse with a period of about 20 milliseconds requires extremely high accuracy. Subtle changes in pulse width correspond to changes in the steering gear angle. Only by sending signals accurately through a microcontroller or a specialized steering gear control board can the steering gear rotate as expected. Therefore, if your programming skills are poor, you will indeed encounter some obstacles in playing with the servo.

The structural difference is quite obvious. One has a naked body and the other has a brain.

If you take a look at a motor, it basically consists of a rotor, a stator, a casing, and two wires. The structure is simple, the leather is durable, and the price is cheap. You can buy a small motor for just a few dollars. But the disadvantage is that it doesn't know where it is, and it doesn't have any intelligence at all.

The steering gear is different, it is an "integrated package". In addition to a micro DC motor, there is also a reduction gear set, a control circuit board, and a potentiometer (the sensor that feedbacks the position). You see, the extra ones are used to "use your brain." Therefore, the steering gear is much more expensive than the motor, but in exchange it can control the angle accurately.

Accuracy requirements determine whether to choose a circle or a fixed point

If your application scenario is to keep the wheels turning and the fan blowing, then the motor is fine. It doesn't care about precise position, only speed and torque. Moreover, the motor can rotate continuously as many times as you want, with no angle limit.

Conversely, if your device requires your arm to be raised at a certain angle and the camera to be pointed in a certain direction, then you must use a servo. The positioning accuracy of the steering gear is usually within a few degrees, and the better performance can reach about 1 degree. And the steering gear has angle limitations. The angle range of the ordinary steering gear is 0 to 180 degrees. A few servos have 360 degrees, but those types of servos cannot actually perform continuous rotation. They mainly rely on signal control to determine the angle of rotation.

The working principle of the steering gear is to drive the internal motor by receiving specific signals to achieve precise angle control. Steering gears play a key role in many automation equipment and robotic applications. It can accurately adjust the arm or camera to the specified angle position according to the preset instructions, providing a strong guarantee for the normal operation of the equipment. Whether it is simple model production or complex industrial automation scenarios, the steering gear has become one of the indispensable components due to its stable performance and precise control.

Common rollover cases are caused by model selection

The most typical car rollover I have seen is to make a robotic arm and use a motor to drive the joints. The guy thought the motor was cheap and added an encoder. After struggling for a long time, he still couldn't get it to stop at an angle stably. Why? Because the motor itself does not have a position closed loop and relies entirely on external sensors, the response is slow and prone to overshoot. Later, the servo was replaced and the problem was solved immediately.

There are also people who are making smart car steering. Some people directly use the motor to drive the front wheel steering, but they find that they have to add a bunch of connecting rods and limits, and they always go off track. In fact, the car uses a high-torque servo for steering, which is directly connected to the steering arm. It is simple and reliable, and debugging is also hassle-free. If you don't believe it, go to Taobao and search for "car steering gear" and look at the well-selling finished products. They are basically steering gear solutions.

Calculate budget and complexity clearly

The motor solution is really cheap, but you have to build the drive circuit yourself, and you have to solve the problem of position feedback. If only continuous rotation is required, the cost advantage of the motor is very obvious. But if you need precise control, the cost and time of adding an encoder and implementing closed-loop control later may be higher than using a servo directly.

The steering gear may seem expensive, but it is a "one-stop shop". You can just buy it, connect it to the line, and send signals, so you don’t have to worry about the driver and feedback yourself. Especially suitable for quickly verifying ideas and making product prototypes. And now there are many types of servos, ranging from small servos of 9 grams to high-torque servos of tens of kilograms. They have standard interfaces and are easy to replace.

I don’t know if the innovative product you are making now requires the wheel to rotate all the time, or the joints to be in precise position? Chat about your project in the comment area and see if I can help you with your selection. If you find this article useful to you, please give it a like so that more friends who make products can see it.