TECHNICAL SUPPORT
Published 2026-03-06
When playing withservos, especially those with slightly more complex linkage controls, have you ever encountered this situation: Theservos are obviously fine when tested alone, but once installed in a project, they either shake non-stop, or the movements are not smooth, or even get stuck directly? 80% of them fell into the pit of "server conversion operation procedure". Simply put, this program converts your control signals into precise actions that theservocan understand and execute. If you don't understand it, the project will easily go wrong.
This thing is actually a piece of code written in your main control chip (such as STM32). Its core job is to convert the "angle value" or "speed value" we set into a PWM (pulse width modulation) signal that can be recognized by the steering motor. You can think of it as a translator, turning the idea "I want the robotic arm to lift to 30 degrees" into a series of precise electrical pulses to drive the motor in the steering gear to rotate. Without this program, the instructions issued by your control panel are just a bunch of gibberish, and the servo has no idea what to do.
When many people encounter servo vibration for the first time, their first reaction is "the servo is broken" or "the power supply is not enough." In fact, many times, the culprit is that the "refresh rate" in the conversion program is not set correctly. Most analog servos need to receive a stable pulse signal every 20 milliseconds (that is, a frequency of 50Hz) to maintain position. If your program is dealing with other tasks, causing the signal sent to the servo to be intermittent or with inaccurate time intervals, the servo will constantly adjust its position within a small range, making it look like it is shaking. Therefore, ensuring that the timer for sending PWM waves in the program is accurate enough is the first step to solve the jitter problem.
When making a bionic robot or a multi-axis robotic arm, it is a headache to have several servos move together. If the programs are processed one by one, you will find that the servo "finishes one movement, and then the other moves", and the movements are very stiff and unnatural. The correct approach is to create an "action group" or "action queue" in the program. What does it mean? That is to first calculate the target angles of all servos at this moment, and then update the PWM output of all servos at the same time in the same time slice. In this way, all servos can start moving to the target position at the same time, achieving smooth and coherent compound movements, such as a robot dog taking a smooth step.
Have you noticed that if you directly turn the servo from 0 degrees to 90 degrees instantly, the movement will appear "stunned", and the start and stop will be very fast, which can easily cause the mechanism to shake. This is the missing link of "interpolation operation". An excellent conversion program will not directly give the end position, but automatically calculate and insert many intermediate points between the starting point and the end point. Just like the middle frame in a cartoon, let the servo go one step at a time. You can program the servo to perform uniform acceleration and uniform deceleration movements, so that its movements will look very soft and smooth, and it will also protect the mechanical structure.
There are a wide variety of servo control boards on the market, and you have to choose one according to your own needs. If you just have fun and use the servo to make a gimbal, then an ordinary 16-channel PWM driver board (for example) is enough. It communicates through the I2C interface and can help you save the computing resources of the main control chip. But if you are making a complex legged robot, you have to consider a high-performance control board with serial communication or even CAN bus. This kind of board not only has higher control accuracy, but can also feedback the current angle, temperature and load of the servo, allowing you to monitor the status of the servo in real time in the program and perform more complex closed-loop control.
Any steering gear has mechanical clearance, which is called "backlash". For example, if you ask it to rotate 10 degrees, it may only rotate 9.5 degrees. When you ask it to rotate back to 0 degrees, it may stop at 0.5 degrees. This is why "dead zones" need to be dealt with in conversion procedures. An experienced approach is to add a "correction factor" to the target value of the program. When you find that the servo does not reach the expected angle, give a slightly "over" command in the next command; or when judging whether the servo is in place, set an allowable error range instead of staring at absolute 0 degrees. This can effectively prevent the servo from tossing back and forth between one or two precision units due to hysteresis.
Must add! And this is the key to taking the project from "can run" to "stable running". Your conversion program can't just be an obedient signal transmitter, it must also be a smart "security guard." For example, add "lock protection" to the program. If the servo does not turn to the specified angle for several seconds (it may be stuck), the power will be cut off immediately to prevent burning the motor. Another example is "overtravel protection". If your mechanical structure only allows the servo to rotate 180 degrees, then the program must filter out any illegal instructions exceeding 180 degrees to prevent the servo from hitting the limit block and being damaged.
Having said so much, I wonder if you have ever been troubled by a particularly strange phenomenon in the steering gear when working on a project? For example, the noise is extremely loud or the fever is severe? Welcome to share your pitfall experience in the comment area, let’s discuss and solve it together! If you find the article useful, don’t forget to like it and share it with more friends.
Update Time：2026-03-06
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