TECHNICAL SUPPORT
Published 2026-02-25
Friends who are engaged in steering gear development must have encountered this situation: the steering gear is installed and it moves without any problems, but it just feels like it is not moving accurately, either shaking violently or unable to return to the desired position. At this time, nine times out of ten, the position feedback is not adjusted properly. The so-called position feedback, to put it bluntly, is to let theservoknow where it is turning now, and the "adjustment" we make is to make the controller agree with this feedback signal. Only when this step is done well can the accuracy and stability of theservobe truly brought into play, and subsequent actions can be executed reliably.
Many times we get theservoand make sharp adjustments, but the adjustment becomes more and more chaotic. The root cause is that the first step of judging the standard is not correct. You have to first return the servo to a physical midpoint, usually by manually turning it to the middle of the mechanical stroke, and then use a tool to read the feedback voltage or angle value. This value is your baseline. If the reading jumps sharply when the servo is in a stationary state, it means that the feedback itself has interference, and you need to check the circuit first or change the servo and then adjust it. Once the baseline is stable, everything that follows will make sense.
The biggest headache for many friends who are just getting started is that it will not move when given a signal, but will move randomly when there is no signal, which is the so-called slow response and overshoot. The core behind this is actually the fight between PID parameters. If you adjust the parameters too gently, the servo will be unresponsive, like an old man who hasn't woken up; if you set the parameters too hard, it will overcorrect, and it will not be able to stop the car when it reaches the target position, and it will shake a few times before it stops. So the difficulty in adjustment is not that you don't know how to tighten the screws, but that you haven't understood how these three parameters work on this specific servo.
Don't just think that you can adjust the servo arm just by observing whether it shakes with your naked eyes. If you act entirely by feeling, the success rate is really low. You need at least a controller that can output PWM signals, such as a dedicated servo tester. With such a tool, you can accurately control the servo to turn to a specific angle. More importantly, there must be a way to obtain feedback signals. If you are facing an analog servo, use a multimeter to check the voltage; if you are facing a digital servo or a servo with a serial port, print out the angle data directly on the computer. Only with this data can you really debug the steering gear with your eyes open, instead of blindly blindly with your eyes closed.
Once you have a suitable controller to output a PWM signal and accurately control the servo angle, the next step is to ensure that the feedback signal is accurately read. For analog servos, using a multimeter to check the voltage is the way to obtain feedback; for digital servos or servos with serial ports, printing angle data on the computer is an effective feedback method. With these feedback data, debugging the servo is like having clear guidance. It is no longer a blind operation without a clue, but precise adjustment based on actual data, which greatly improves the success rate of adjusting the servo.
A stupid method that I often use, but it is particularly effective, is the "three-step" strategy. The first step is to turn off the integral and differential functions, leaving only proportional control. After setting a target position, slowly increase the proportional coefficient until the servo begins to vibrate slightly near that target point.
The second step is to add differential to suppress this oscillation. Increase it a little at a time until the servo can stop stably and no longer vibrate. In the last step, if you find that the servo is always a small distance away from the target position, that is, there is a static difference, then add a little more points to bring it back. During this process, remember to test gradually from low speed to high speed.
Vibration in the servo is really annoying, but you need to clearly distinguish what type of vibration it belongs to. If high-frequency and small-amplitude jitter occurs when the servo is in a stationary state, it is most likely that the noise carried by the feedback signal itself has been amplified. In this case, you can perform a simple sliding filter operation on the feedback value in the program, or slightly increase the amount of differential to suppress this jitter.
If the servo vibrates during movement, it is caused by parameter mismatch. At this point, just follow the steps mentioned above and do it again. In addition, from a physical perspective, one reason is that the load driven by the steering gear itself has elasticity or clearance. When encountering this situation, it is necessary to consider strengthening the mechanical structure.
Don't think that everything will be fine if the servo can stop at the designated position. Actual testing is the last word. You have to give it a continuously changing instruction, such as making it swing sinusoidally, and see if it can keep up and whether there is any obvious lag. Then suddenly give a step signal and see if the moment it goes from rest to start to stop is crisp and clear. The most important thing is to repeat the above test with a load, because it is too common for it to run smoothly without a load and to lie down when it is loaded. Only when these scenarios are passed can your adjustment be truly successful.
Steering gear adjustment is actually a job of patience and experience. Everyone's equipment and load are different, and no set of parameters can be used all over the world. What is the most troublesome problem you encounter during debugging? Is it the jitter that cannot be adjusted, or is it the error that can never be eliminated? Welcome to leave a message in the comment area to share your experience. Let's discuss and solve the problem together. If you find it useful, don't forget to like and forward it so that more friends can avoid detours.
Update Time：2026-02-25
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