TECHNICAL SUPPORT
Published 2026-03-26
When it comes to product innovation, the biggest fear is “having an idea but getting stuck”. Especially when making smart devices that require flexible rotation, you must have encountered this problem: you want the camera to follow the person steadily, or the robotic arm to grasp accurately, but you only have a single-axisservoat hand, and it always shakes its head and is disobedient when moving. In fact, the key to solving this problem lies in understandingthe schematic diagram of the dual-axisservocontrol gimbal. Today we will put aside the complicated mathematical formulas and break down the secret behind it as if we were talking about everyday things.
Many people just start working on a project and think that one servo is enough, but they are dumbfounded as soon as the device starts running. A single axis can only move in one plane, just like you can only turn your head left and right, but you can't raise your head or lower your head. The dual-axis servo gimbal is different. It is equivalent to adding a "neck" and "waist" to your equipment. One servo is responsible for horizontal rotation (yaw axis), and the other is responsible for up and down pitch (pitch axis). With the two together, your camera or sensor can achieve 360-degree tracking without blind spots. The increased freedom brought by this structure is a key step in making the product from "silly" to "flexible and smart".
Speaking of this, you may want to ask, how can two servos be stacked together without fighting? The core design in the schematic diagram is structural stacking. A common approach is to use a U-shaped bracket to "hang" the servo responsible for pitching on the servo responsible for horizontal rotation. In this way, the two servos perform their respective duties without interfering with each other. This is not only the ingenuity of the mechanical structure, but also the cornerstone of the control logic. When you draw the schematic diagram, remember to label the signal lines and power lines of the two servos separately. Don't mix them together, otherwise the board will be burned out during debugging and the gain will outweigh the loss.
Don't rush to place an order to buy the most expensive servo. If you choose the wrong type, no matter how good the schematic is, it will be useless. For a two-axis gimbal, the first thing to look at isthe torque, which is how strong the servo is. If you only use it for a thumb-sized camera, a 9g micro servo is more than enough; but if you want to set up a sports camera or even a mobile phone, you will need a high-torque servo with metal gears of more than 20kg. If you choose a small one, the gimbal will shake like Parkinson's; if you choose a large one, it will waste space and power, and the power module on the schematic diagram may not even be able to carry it.
The second point is more critical, it depends on whether it isan analog servo or a digital servo. The response of the analog servo is slow and the accuracy is poor. It is OK for simple light control, but basically useless for stable gimbal. It is strongly recommended that you choose a digital servo. Although it is more expensive, it has fast response speed, high accuracy, and is compatible with mainstream PWM control signals. When drawing the schematic diagram, don't forget to connect a separate voltage stabilizing module to power the servo. Many novices overturned their cars because they connected the servo power supply and the controller power supply together. As soon as the servo motor turned, the microcontroller restarted directly. I understand this pain all too well.
When I get the schematic diagram, the biggest fear is facing a bunch of red, black, and yellow wires and not knowing where to insert them. Let’s break down the standard connection method. Usually the servo has three wires:red is the positive pole of the power supply, brown or black is the negative pole, and yellow or orange is the signal wire. In a dual-axis gimbal, you need to twist the red wires of the two servos together and connect them to the positive terminal of the external power supply; twist all the brown wires together and connect them to the negative terminal of the power supply and the GND of the control board. This step is called "shared ground", which is the prerequisite to ensure the stability of the control signal. Without it, the signal will be like a train without track, and it will not run steadily at all.
Then there is the signal line, which is the "soul". You need to connect the servo signal line responsible for horizontal rotation to a PWM port (such as D9) on the control board; connect the servo signal line responsible for pitch to another PWM port (such as D10). If there is a potentiometer or a joystick in your schematic, it is even simpler. Connect the X-axis and Y-axis outputs of the joystick to the analog input ports of the microcontroller respectively. When wiring, remember a rule:separate strong currents, common ground for weak currents, and independent signals. Before each connection, use a multimeter to check whether the power supply is short-circuited. This habit can help you save a lot of money on buying a new servo.
In fact, it is not difficult to draw a schematic diagram. Don't think of it as too sacred. You can think of it like drawing a "city traffic map."The core componentsare a single-chip microcomputer (such as STM32), a dual-axis joystick module, two servos, and a regulated power supply. First draw the power module. It is like the "power plant" of the city, responsible for delivering stable 5V or 6V power to all components. Then put the microcontroller in the middle as a "traffic command center".
The next step is to connect the wires. Connect the VCC and GND of the joystick to the power supply, and connect its X-axis and Y-axis outputs to the analog input pins of the microcontroller. Then connect the signal lines of the two servos to the corresponding digital output pins of the microcontroller. The most critical point is thatthe GND (negative pole) of all components must be connected togetherto form a common reference point. The schematic diagram should be standardized so that your eyes will not be confused when you are making boards or soldering wires manually. Many online drawing software now have ready-made steering gear libraries. You can just drag them out and use them, saving time and effort.
Now that the hardware is connected, how do you make it move? The control logic is actually very simple, just "move the rocker and follow the servo". The microcontroller constantly reads the analog values of the X-axis and Y-axis of the joystick (0-1023), and then converts this value into the angle required by the servo (0-180 degrees) through an algorithm called "mapping". For example, when the joystick is pushed all the way to the left and the X-axis value becomes smaller, the program will rotate the horizontal servo to 0 degrees; when the joystick is returned to the center, the value returns to 512, the servo will rotate back to 90 degrees. The calculation formula in the middle is just a matter ofmap()function.
If you want the gimbal to automatically track faces, you need to introduce a visual algorithm. At this time, the camera module must be added to the schematic diagram, and the microcontroller must not only read the joystick, but also the coordinate data of the camera. To put it simply, it is to let the camera find the center point of the face, then calculate the deviation value between this point and the center of the picture, and then use this deviation value to "finely adjust" the angle of the servo. This kind of closed-loop control looks high-end, but in fact, the underlying logic is "large deviations will turn faster, small deviations will turn slower." If this logic is run through, your smart pan/tilt will take shape.
No matter how well you draw the schematic diagram, you will inevitably encounter pitfalls during debugging. The most common one isservo vibration. If you find that the servo is swaying in place like it is convulsing, it is probably a power problem. Either the battery power is insufficient, or the power cord is too thin and cannot supply current. The solution is very simple. Add a large capacitor (such as 470uF) to both ends of the servo power supply. Adding this to the schematic diagram is like adding a buffer to the viaduct, which can instantly stabilize voltage fluctuations.
Another pitfall isnot returning to the center. The joystick let go, but the gimbal tilted its head and refused to return to the straight position. This is usually because you forgot to set the "neutral point" of the servo. In the initialization part of the program, you must explicitly write a PWM value of 90 degrees (or the neutral position you set) to the two servos so that they can "stand straight" first. If the mechanical structure itself causes uneven stress on the servo due to an unstable center of gravity, then you need to check the mechanical coordination on the schematic diagram. In the U-shaped bracket design, try to make the center of gravity of the camera fall on the rotation axis of the pitch servo. This way, the servo will save the most effort and have a longer life.
On the road to DIY smart products, understanding this schematic is only the first step. By making a dual-axis servo gimbal, you will find many practical skills hidden in books, such as how to make wiring more beautiful and how to adjust PID to make the picture more stable. When making a dual-axis servo gimbal, have you ever encountered a situation where the servo was directly burned out due to wiring errors? Welcome to share your "rollover" experience in the comment area, and let's avoid pitfalls together. If you find today's content useful, remember to like and follow me, and I will guide you step by step through more smart hardware designs.
Update Time：2026-03-26
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