TECHNICAL SUPPORT
Published 2026-03-22
Many friends will encounter a headache when playing with robots and making automated equipment: theservoeither turns too fast and hits the limit; or it turns too slow and the movement is sluggish. I want it to move at a constant speed, neither fast nor slow, but I find that the ordinaryservoin my hand cannot directly adjust the speed. In fact,controlling the speed of aservois really not that mysterious. The key lies in choosing the right servo and using it in the right way.
Ordinary servos receive PWM signals, which only recognize the target angle and not the path speed. If you ask it to go from 0 degrees to 180 degrees, it will rush over at the fastest speed, and the middle process is completely uncontrolled. It's like when driving, you only tell the driver the destination, but don't give the accelerator or brake. He can only step on the accelerator to the end. This "either stay still or rush" characteristic becomes a big trouble in many fine action scenes, such as a robot grabbing an egg if it goes too fast and crushes the egg.
If you want the steering gear to achieve uniform motion, the core idea is to transform the "one step to the finish" method into a "multi-step gradual" mode. If you are using an ordinary servo, you can use the control panel to break down a large angle movement into dozens of tiny steps. Each step only turns a very small angle and adds a delay in the middle. For example, rotating from 0 degrees to 180 degrees is divided into 180 steps, with each step turning 1 degree and delaying 10 milliseconds. In this way, the total movement time is 1.8 seconds, and the movement process will appear smoother. Although this method is a little troublesome in programming, it can be easily achieved using common or STM32, and the cost is extremely low.
For the realization of uniform motion of the steering gear, the key is to transform the original "one step to get it done" method into "multi-step gradual". For ordinary servos, a large-angle movement can be subdivided into dozens of small steps with the help of the control panel. Each step only makes a small rotation, and a delay is added in the middle. For example, from 0 degrees to 180 degrees, it is divided into 180 steps, each step turns 1 degree, the delay is 10 milliseconds, the total time is 1.8 seconds, and the movement process will become smooth. Although the programming of this method is slightly complicated, it is easy to implement using common STM32 and the cost is very low.
Digital servos are more suitable for speed control than analog servos. Its core advantages are fast response and accurate positioning, and many mid-to-high-end digital servos themselves support speed control commands. You only need to send the command "speed value + target angle", and the servo will rotate at a constant speed at the set speed. This is equivalent to equipping the servo with an "intelligent driver". You no longer have to worry about step-by-step and delay. You can do it with just one line of instructions when writing code. In addition, the digital servo also has position feedback, so you can know where it is turning in real time, which facilitates closed-loop control.
When choosing a speed control servo, you need to pay close attention to three key parameters. The first is the type of servo. Priority is given to smart servos that support bus communication, such as serial servos and CAN bus servos. They generally have built-in speed control functions. The second is the response speed. You need to check whether its no-load speed and locked-rotor torque fit your application scenario. For example, the speed requirement of a robot joint is low speed and high twist, while the gimbal requires high speed and low twist. The third is control accuracy. You can check the width of the servo dead zone. The smaller the dead zone, the more delicate the speed control will be. Don’t just focus on the price. Cheap servos often have trouble even doing basic angle positioning.
In addition, in the actual selection process, many factors need to be considered comprehensively. In addition to the three main parameters mentioned above, we must also pay attention to the stability and durability of the steering gear. Because different application scenarios have different requirements for servos, only a comprehensive evaluation can select the speed control servo that best suits your needs and ensure the efficient operation of the equipment. For example, in some situations that require extremely high precision, the control accuracy of the steering gear is particularly important; and in applications that require stringent speed, response speed becomes a key consideration. In short, we must carefully weigh all factors and avoid neglecting other important features due to one-sided pursuit of one aspect.
Let me give you a very common example, which is the bionic mechanical palm. In this bionic mechanical palm, we choose a serial port servo with speed control to drive the five fingers. After careful setting, the closing speed of each finger is 0.5 seconds. In this way, when it grabs the glass, its fingers will tighten at a slow speed to avoid crushing the glass with excessive force.
When driving the large joints of the arm, the speed is set to 0.2 seconds to ensure that the movement can be carried out quickly without collision. By individually adjusting the speed of each joint, the entire manipulator not only has a high degree of flexibility, but also ensures safe operation. You see, speed control is not about showing off skills, but actually solving the problems of "power" and "accuracy".
If you are just getting started with servo speed control, you can follow these three steps. The first step is to purchase a sample of a smart servo that supports speed control, such as a bus servo of a certain brand. The price ranges from tens to hundreds of yuan. When purchasing, do not purchase too much at one time.
The second step is to download the debugging software or SDK provided by the manufacturer, use the USB to serial port module to connect the servo, and then drag the speed slider directly in the software to feel the movement effect of the servo at different speeds. The third step is to write a simple test program. First, control a single servo to move back and forth at different speeds. After confirming that there are no problems, extend it to multiple servos. It is recommended that you record the parameters during the debugging process to form your own "speed parameter table", so that you can directly look up the table and call it when doing projects in the future.
Does your product also have "violent actions" caused by uncontrollable speed of the servo? You might as well try the method mentioned today, replace two servos that support speed control, and feel the transformation from "rushing and crashing" to "lifting with ease". If you encounter specific problems in selection or debugging, please leave a message in the comment area and we will find a solution together.
Update Time：2026-03-22
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