TECHNICAL SUPPORT
Published 2026-03-24
Have you ever encountered such a problem: You want theservoto turn clockwise, but it turns counterclockwise; or you want it to turn to a specified angle, but it is completely out of control? When many people use a steering gear for the first time, they will have a headache about forward and reverse steering. In fact, if you understand the working principle of the steering gear, this problem will be easily solved.
The biggest difference between a steering gear and an ordinary DC motor is that it does not change the direction by connecting the positive and negative poles. You can think of aservoas a rotating dial. If you give it a "position command", it will automatically turn to that position. If the command angle is larger than the current angle, it will rotate forward; if it is smaller than the current angle, it will rotate reversely. ️So the key to controlling forward and reverse rotation is not to change the power line, but to send it a "position command" through the signal line.
This "position command" is actually a continuous pulse signal. When you want theservoto turn 180 degrees clockwise, give it a specific pulse width; if you want it to go back to 0 degrees counterclockwise, give it another pulse width. There is a circuit inside the steering gear that compares the current angle with the target angle in real time, and then automatically decides which direction to turn. Simply put, you only need to tell it "where to go" and it will figure out "how to go" by itself.
You may have heard the word PWM, which sounds very professional, but in fact it is the English abbreviation of "Pulse Width Modulation". For the steering gear, the PWM signal uses pulses of different widths to represent different angles. Common servos use a frequency of 50Hz, which means they send 50 pulses per second. ️The width of each pulse varies between 1 millisecond and 2 milliseconds, 1.5 milliseconds corresponds to the middle position, 1 millisecond is the most left or top, and 2 milliseconds is the most right or bottom.
You may ask, how to control the steering speed? With a normal servo, the steering speed is fixed and you can only control the final position. But some continuous rotating servos are different. They stop at 1.5 milliseconds. If they are less than 1.5 milliseconds, they will turn in one direction. If they are greater than 1.5 milliseconds, they will turn in the other direction. The farther the pulse width is from 1.5 milliseconds, the faster it will turn. So controlling forward, reverse and speed is actually adjusting the pulse width.
If you want to quickly control the servo, it is most worry-free to just buy a servo control board. There are two main types on the market: one has a USB interface and can be directly connected to a computer for software debugging; the other has a microcontroller and can run independently. For product innovation, if what you want to do requires simultaneous control of multiple servos, a board with a microcontroller is more convenient, and the program can be run offline after writing it.
If your project is relatively simple, such as controlling one or two servos, you can just use a microcontroller development board. ️They can generate PWM signals by themselves, no need to buy an additional control board. But please note that if there are many servos or the torque is large, the power supply must be supplied separately. Do not use the 5V on the development board directly, as it will easily burn the board. When choosing a control panel, read more user reviews and cases, and find one with complete technical documentation. This will save a lot of time in subsequent debugging.
There are mainly several steering gear angle ranges on the market: 90 degrees, 180 degrees, 270 degrees and 360 degrees. The first three are ordinary servos, which can only rotate to a specified angle and cannot rotate continuously. 180-degree servos are the most common and are suitable for scenes that require positioning such as robot joints and camera gimbals. 90-degree servos are usually used in small models, such as the steering mechanism of remote control cars.
Pay special attention to the 360-degree servo, which is actually divided into two types: one is a true continuous rotation servo, you can control it to rotate continuously, but you cannot control the angular position; the other is a 360-degree programmable servo, which can rotate more than one circle and still position. ️If your project requires wheel rotation, then choose a continuous rotation servo; if you need precise angle control like a robotic arm, ordinary 180 degrees is enough. Don’t buy the wrong one, otherwise the project may become unusable.
For example, it is actually very simple to write a program that makes the servo rotate back and forth. First use #
If you want it to swing back and forth at a constant speed, you can gradually increase the angle value between 0 and 180 degrees. For example, use a for loop to increase 1 degree each time from 0 to 180, adding a 15 millisecond delay in the middle, so that the servo will turn smoothly. Same goes for reverse. ️Remember, different servos have different sensitivities to delay time. If the steering is not smooth, you can adjust the delay appropriately and try from 10 to 30 milliseconds. The code logic is clear, and all that's left is to try it a few more times to find the parameters that best suit your project.
Many novices will encounter the problem of the servo "buzzing" but not turning. This is usually caused by insufficient power supply. The current when the servo is started is very large. This situation will occur if USB power is used or the battery voltage is insufficient. The solution is to supply power to the servo separately. The voltage is generally between 4.8V and 6V. At the same time, ensure that the power supply current is sufficient. A small servo is more than 1A, and a large servo may require 2-3A.
There is also a situation where the steering gear keeps shaking when it turns to a certain position. This is called "rudder shaking". It may be signal line interference, or the servo load may be too large. You can check whether the line is too long and try to control it within 30 cm; or check whether the thing hanging on the servo arm is too heavy and exceeds its torque range. ️Don’t worry if you encounter a problem. Check the power supply first, then the signal line and load. These three factors cover more than 80% of faults.
What headaches have you encountered when using a servo to control steering? Welcome to share your experience in the comment area, and we can discuss and solve it together!
Update Time：2026-03-24
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