TECHNICAL SUPPORT
Published 2026-02-19
I believe that many friends who play withservos have encountered this situation: they powered on theservos with great expectations, but as a result, it swayed left and right like a drunk man, but could not stop steadily at the designated position. This is indeed quite a headache. To put it simply, the steering gear "shaking its head and shaking its head" is telling us that there is something wrong with the signal, power or itself that controls it. This is usually not a single failure, but one of multiple links not coordinating well. Let’s talk about how to help yourservoregain a “sense of stability” step by step.
The most intuitive reason why the servo moves erratically is that the control signal it receives is unstable. You can think of it as a very obedient steering wheel. It is always listening to the instructions of "turn left" or "turn right". If this command fluctuates left and right, intermittently, it will naturally follow the swing from left to right. This signal usually comes from your main control board (such as STM32). It may be that the PWM wave generated in the code is not accurate enough, or it may be that the signal line is subject to external electromagnetic interference, turning the originally clear password into "noise".
Another possibility is that there is a problem with the "feedback system" of the steering gear itself. There is a potentiometer inside the steering gear, which is used to report the current angle it turns to in real time, so that the controller can know "whether the command has arrived." If this potentiometer has poor contact, or is worn, it will report the wrong position. The controller thinks that it has not yet reached the position, so it will continue to rotate the motor, resulting in continuous searching and jittering. It's like you've clearly arrived at your destination, but the navigation keeps saying you haven't arrived yet, making you keep going in circles.
Insufficient power supply is the number one culprit that causes the servo to vibrate or even become weak.Inside the steering gear is a small motor, which requires a large current when starting and stalling. Imagine that when you want to push a heavy door with all your strength, does it require a huge burst of strength in an instant? The same goes for the steering gear. If the power supply cannot provide this large current instantly, the voltage will be pulled down instantly.
It doesn't matter if it's low. The first thing to suffer is the control chip of the servo itself. Unstable voltage will cause errors in its logic operations. At the same time, the signal given to it by the main control board may also become chaotic due to voltage sag. The result is that the servo has no energy to work because it is "not full" and can only try to reach the target position while trembling. Therefore, when you find that the servo is shaking, the first thing to suspect is the power supply. Especially if you are using a computer USB port to power multiple servos, problems will almost certainly occur.
Software optimization is a key step in solving the jitter problem. First, make sure your code that generates the PWM wave is stable and accurate. Avoid using delay functions in the main loop, because the microcontroller cannot handle other things during the delay period, which may cause PWM signal interruption. A better approach is to use a hardware timer to generate PWM, or directly call mature library functions like Servo.h, which have been well optimized at the bottom level.
Consider adding the concept of a "dead zone". Determine the target angle and the current angle in the code. If the difference is less than a small threshold (such as 1 degree), simply do not send an update signal to the servo and let it stop there steadily. It's like driving a car. If the destination is just one or two meters in front of us, we usually don't turn the steering wheel anymore and let the car glide over naturally. This can effectively prevent the servo from repeatedly correcting due to small errors near the target position, thereby eliminating jitter.
This is definitely one of the core factors affecting stability. Different servos have different "tempers". For example, there is a big difference between analog servos and digital servos. The analog servo relies on a continuous PWM signal to maintain its position, and it will move accordingly if the signal fluctuates slightly. The digital servo has an internal processor that can process signals at a higher frequency, respond faster, position more accurately, and naturally be more stable.
There are also differences in torque and size of servos. If you equip a joint that requires a lot of strength, such as a robot's big arm, with a small-torque micro servo, it will continue to "struggle" because it cannot carry the load, manifesting as continuous shaking and heating. Therefore, choosing a servo is like putting a saddle on a horse. You must calculate the required torque and response speed according to your application scenario. If you choose the right model, more than half of the stability problem will be solved.
A small oversight in the hardware is often the source of servo vibration. The most common problem is that the steering wheel is not installed correctly, or the linkage mechanism has a false position. Imagine that if the steering wheel is not installed correctly, the steering gear will receive an asymmetrical force when turning, causing it to have to be constantly adjusted to maintain the designated position, which will cause jitter.
In addition, the smoothness of the entire transmission mechanism is also very important. If a joint is too tight, the servo will require extra effort to drive, resulting in excessive load; if it is too loose, a gap (i.e., a false position) will occur, causing the servo to stop, but the end parts can still shake. Both situations will make the control of the servo unstable. Therefore, before debugging, you might as well move your mechanical structure with your hands to ensure that it moves smoothly without any lag or obvious shaking gaps.
Many friends tend to ignore the importance of the ground wire when wiring.The power ground and signal ground of the servo must be reliably connected together.The ground wire is like the base reference point for all electrical signals. If this reference point is not uniform or has a large resistance, ground loop interference will occur.
To give a simple example, the ground potential of the main control board is 0V, but because the ground wire is too thin or the contact is not good, the ground potential of the servo may be raised to 0.1V. At this time, the main control sends a 1.5V pulse signal. For the servo, the actual signal voltage it receives may become 1.4V. This slight deviation is enough to prevent the servo from accurately judging the command. Therefore, please make sure that the ground wires between your power supply, servo and main control board are short and thick, preferably sharing a ground point, so as to give all signals a stable and reliable reference plane.
After reading this, I believe you have a relatively comprehensive understanding of the problem of servo vibration. Next time you encounter your servo shaking its head, you might as well investigate it like a detective from the aspects of power supply, code, model selection, mechanical installation and grounding.
I would like to ask you who are reading the article, during the actual debugging process of the servo, what other strange jitter problems have you encountered, or do you have any unique solutions? Welcome to leave a message and share in the comment area, let’s communicate and learn together! If you find this article useful, don’t forget to like it and share it with more friends who need help!
Update Time：2026-02-19
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