TECHNICAL SUPPORT
Published 2026-04-30
Many users searched for "What is the speed at which the steering gear is controlled?"When asking this question, what they actually want to know is how to accurately set the speed of steering gear rotation, and what is the speed range of common servos. It needs to be made clear that in the engineering field, the unit used for steering gear rotation speed is usually "degrees/second" or "seconds/60 degrees" (here "seconds/6"). "0 degrees" means the time required to rotate a 60-degree angle in seconds), and is definitely not "yards". You must know that "yards" are British length units or vehicle speed units, which are not applicable to steering gear-related fields. On this basis, this article will use standard steering gears as an example to give speed control parameters and adjustment steps that can be directly applied.
The rated rotation speed of common 9g and 20g standard servos is generally between 0.12 seconds per 60 degrees and 0.20 seconds per 60 degrees, which corresponds to a rotation rate of 300 to 500 degrees per second. The high-voltage servo, that is, the one powered by 6V to 7.4V, can reach 0.07 seconds per 60 degrees, which is more than 850 degrees per second.
The essential way to control the speed of the servo is to change the update frequency of the PWM (pulse width modulation) signal, or to use segmented delay instructions to change the total time required for the servo to rotate from the current angle to the target angle.
The source is based on the definition of servo system speed in the International Electrotechnical Commission (IEC) 61800-7 standard, as well as the common parameters of mainstream steering gear product specifications, such as Futaba, Hitec and other public data. This is just a parameter reference.
There are some steps that are applicable to Arduino, these steps are also applicable to Raspberry Pi, these steps are also applicable to common development platforms such as STM32, and these steps are not dependent on any specific brand.
The device called an analog servo only supports this situation, that is, a PWM signal with a frequency of 50Hz and a period of 20ms. The speed of its rotation is determined by the internal potentiometer and motor. There is no way to directly adjust the speed through software. The only way to achieve an approximate speed adjustment effect is through segmented movement.
The digital servo can accept higher frequencies, which can reach up to 400Hz. It supports "speed command" or "gradient positioning" and can write the target speed value independently.
Case: A maker made a mechanical claw and hoped that the servo would slowly rotate 90 degrees within 2 seconds.
The solution is not to directly send 90-degree instructions, but to split 90 degrees into 90 steps of 1 degree. There must be a delay between each step, and the delay time is 22ms (the calculation formula for this delay time is, the total time of 2000ms divided by 90 steps, the result is approximately equal to 22ms).
Code logic example(pseudocode):
for (angle = current angle; angleThis method can accurately control the actual rotation speed of any servo to the millisecond level.
Some digital servos have the ability to directly write speed values (such as 0 to 100%). Check the product manual of the servo you own and look for the "Speed Control" or "Slider Mode" register address. Writing 0x00 means maximum speed, writing 0xFF means slowest speed.
During the actual debugging process, there is a useful prompt for article writing, which is "PWM duty cycle and time mapping relationship". Remember this: the core of speed control is not changing the PWM frequency itself (which is always fixed at 50Hz), but changing the time interval between each command.
Q1: The actual rotation speed of the servo is slower than the nominal value. What is the reason?
There are many factors in this situation. First, the voltage is low. Second, the mechanical load may be too large. At this time, the power supply voltage needs to be measured to ensure that it will not be lower than the rated value. For example, this rated value is like 4.8V, and then the additional resistance must be removed.
Q2: Can the servo be made to rotate at a constant linear speed (such as 1cm/s)?
A: There is no way to achieve it directly. The linear velocity must be converted into angular velocity based on the radius of rotation, and then the segmented method is used for control.
Q3: My servo is at the fastest speed when it is started. How can I slow it down?
A: You have to use the segmented movement method. Don't jump directly to the target angle. You need to split it into many small steps and insert a delay.
Q4: What speed does "code" correspond to the servo?
For A, there is no corresponding relationship. The user has misused the unit and needs to ignore the "code" and directly use seconds divided by 60 degrees or degrees per second to communicate.
Q5: Does the speed setting priority of the digital servo have higher priority than the PWM signal?
A: That’s right. After writing to the speed register, the MCU inside the servo will perform smooth control on its own, while the external PWM only provides the target angle.
1. mistake: Change the PWM signal frequency to control the speed.
The specific results were as follows: the steering gear vibrated and whistled, eventually causing it to be burned. The analog servo must lock the frequency at 50Hz!
2. mistake: Directly delay the total time without splitting the steps.
The result is that the servo continues to run at the fastest rotation speed and does not stop until the delay expires. There is no effect of speed adjustment.
3. mistake: Use the low-speed segmentation method in heavy-load scenarios such as robotic arms.
The result is: the motor torque is insufficient, resulting in a stuck situation. When the speed is at a low level, it needs to be matched with a reduction mechanism or the load should be reduced.
Conclusion 1: The orthodox unit of servo speed is "second/60 degrees". At the same time, the orthodox unit of servo speed is also "degree/second". If searching, please use "servo speed control" and "seconds/60 degrees" to obtain accurate information.
Conclusion 2: Even if your servo does not support direct speed adjustment by software, you can still use the method of "segmented movement + delay" to achieve any slow rotation. This is a universal solution for all platforms.
Conclusion 3: To make the speed parameters consistent with the specifications, the power supply voltage must be kept in a stable state, that is, in the range of 4.8V to 7.4V, and cannot exceed the load capacity.
Carry out the operation immediately: select a servo and use Arduino to write a loop program. This loop starts from 0 degrees and reaches 180 degrees. This range is divided into 180 equal steps, and each step is delayed by 10 milliseconds. Then observe whether the actual rotation time is 1.8 seconds? If this is not the case, then carefully check whether the delay in the code process is blocked by other tasks. This is a best practice for verifying speed and mastering control logic.
Once again, the core point is emphasized. In order to control the rotation speed of the servo, it does not rely on a specific brand, nor does it rely on an expensive driver board, but it relies on precise programming of the angle step and time relationship. Please keep this text in a safe place and use it as your standard operating reference.
Update Time：2026-04-30
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