Comparing The Advantages And Disadvantages Of Steering Gear And Stepper Motor, Which One Is More Suitable For Robots?

When engaging in product innovation, does it give you a headache to choose between aservoor a stepper motor? The two brothers can both make things move, but they have completely different temperaments. If they make the wrong choice, the results will be unsatisfactory at best, or the entire project will have to be scrapped and restarted. Don't worry, we'll break them apart and talk about them thoroughly today, and I'm sure you'll feel confident after listening to them.

What is the difference between a steering gear and a stepper motor?

To put it simply, the steering gear is an "obedient soldier". You tell it which angle to turn, and it turns it without saying a word. The stepper motor is more like a "diligent accountant". It takes as many steps as you send it pulses, and each step is clearly counted.

Theservois integrated with a control circuit, potentiometer and reduction gear. You only need to give it a PWM signal, and it can adjust to the target position in a closed loop by itself. Stepper motors are not so smart. You have to rely on an external driver to send pulses. It works completely in an open loop. It depends on where you go. One more step or one less step depends on your instructions.

This essential difference directly determines what kind of work they are suitable for.

What projects are the steering gear suitable for?

The biggest advantage of the steering gear is its high torque and small size. Despite its small size, it can output more than ten kilograms of torque for less than 100 yuan like a standardservo. It can directly drive the mechanical arm to grab a bottle of mineral water without any pressure.

️ Another advantage is that the wiring is simple, with three wires: power, ground, and signal. You don't need to know any PID algorithm, just plug it in and send an angle command, and it will turn steadily by itself. When making smart car servo steering or bionic robot joints, choosing a servo in these scenarios is definitely the first choice for peace of mind.

However, it also has shortcomings, that is, the rotation range is limited. An ordinary servo can only rotate 180 degrees. If you want it to rotate continuously, there is no way. You have to buy a special multi-turn servo, and the price has also gone up.

What are the strengths of stepper motors?

The specialty of stepper motors is precise positioning. You send it 400 pulses, and it will make one complete turn. If you send another 400 pulses, it will make a second turn, and the error will not accumulate. For equipment such as 3D printers and engraving machines that require repeated trajectories, stepper motors are the absolute main force.

Another advantage is that it can continue to rotate without any angle limit, and you can rotate it as many times as you want. Combined with the screw guide rail, it is very stable for long-distance reciprocating motion. Moreover, the control logic is very straightforward. Unlike the servo, which has to adjust the dead zone and the center point, the stepper motor has a strong "stepping feel" when it actuates.

The disadvantage is that the heat is obvious, especially when the rotor is blocked for a long time or running at low speed, it is a bit hot to the touch. Also, the torque will drop faster when running at high speed, unlike the servo that "does wonders with great force".

The three most troubling questions when choosing a model

The first question that many people struggle with is: If I want high accuracy, do I have to step up? Not necessarily. The servo is used in scenarios where the steering gear is used to move a thousand pounds, and the accuracy is completely sufficient, unless your tolerance is required to be less than 0.1 mm.

The second common confusion is: I need a lot of strength, is it better to choose a servo? This is indeed the case in medium and low speed scenarios, but if you want the motor to rotate continuously at high speed, a stepper motor accelerator and reducer is a better combination. The servo will easily overheat if it rotates continuously for a long time.

The third question is: Which one is easier to get started with? Definitely the steering gear. You can buy it and plug in the signal cable and it will run. The stepper motor also needs to be equipped with a driver, current adjustment, and subdivision. Newbies can easily be confused by jumper caps and DIP switches.

How to choose the best deal if you have a limited budget?

If you are doing prototype verification and have a budget of only a few hundred yuan, then I strongly recommend giving priority to domestic servos. Nowadays, servos from brands like Huisheng and Yinyan, which cost only a few dozen yuan, are already very capable, and you won’t feel bad if they break down.

As for the stepper motor, if it is a small torque application, buy a cheap 42 stepper motor plus a driver. A set costs sixty or seventy yuan, which is very cost-effective. However, please note that the subdivision number of cheap drivers may be false, and the actual noise may be too loud.

If it is mass production, you have to be willing to spend money on the stepper motor driver and replace it with a silent driver chip. The overall machine experience will be greatly improved, and the user can clearly feel that "this thing is well made."

How to use it in combination in actual projects

I have seen many smart product managers who use servos and stepper motors together. For example, when making an intelligent visual robotic arm, the big arm uses a stepper motor as a linear module to pursue large strokes and repeated positioning; the wrist joint uses a servo to pursue compact and supple movements.

There are also friends who make photography slides. They use stepper motors to move the slide, because it can accurately know how many millimeters it has moved; and use servos to tilt the gimbal, because it has fast response, sufficient torque, and can withstand the weight of the camera.

This idea of "leveraging strengths and avoiding weaknesses" is particularly worth learning from. Don't be blind to black and white. Who says that only one type of motor can be used in a device?

When should you decisively give up the servo or stepper?

If your project requires the motor to work in extreme environments, such as high temperature, high humidity, and strong vibration, the potentiometer in the ordinary servo is prone to problems. In this case, you must either use a stepper plus encoder, or directly use a brushless servo.

On the other hand, if extremely low cost and high volume are required, such as making a batch of small toys, the cost of the stepper motor drive circuit is still high, and the steering gear solution will have more advantages.

There is also a type of scenario that requires extreme silence. Even if the stepper motor is driven silently, it will still have a slight high-frequency whine. The sound of the servo gear rotation is closer to white noise, which some people find more comfortable.

I don’t know if the project you are working on is stuck with insufficient accuracy, insufficient strength, or the budget has exceeded the standard? Welcome to chat about the selection problems you encounter in the comment area. I will pick out a few typical detailed answers. If you find this article useful, don’t forget to like and share it with your colleagues in R&D.