TECHNICAL SUPPORT
Published 2026-02-12
Are you also struggling with a question: When making a smart car, should you install a steering gear? Some people on the Internet say that the steering gear is the soul, while others say that you can still run happily without a steering gear. As someone who has played with seven or eight small cars, I can tell you with certainty - the difference between the two is really big, and there is no absolute good or bad. The key depends on what project you do.
When turning a car with a steering gear, it is like turning the steering wheel of a car, and the wheels will actively deflect. The biggest benefit of this steering method is accurate pointing. Especially in a tracking car that needs to run along the white line, theservocan quickly respond to the PWM signal and allow the front wheel to move steadily along the line. You don’t have to worry about the car being sloppy, and you can worry less about debugging it.
️ Another advantage that is easily overlooked is that theservocomes with a reduction gear set and position feedback. This means that it can output a lot of torque and can still turn the wheels even if the car is heavy and the ground is rough. I tried using an ordinary TT motor for steering, and it got stuck when it encountered the edge of the carpet. After changing the steering gear, I ran over it directly. The sense of calmness was really different.
Cars without a steering gear usually rely on differential steering - that is, the left and right wheels rotate at different speeds, like a tank or a sweeping robot. The structure of this solution is extremely simple. It can run with two motors and a universal wheel, and the cost is very low. Many starter kits costing dozens of dollars do this, and you can even build a running car in half an hour.
But the problem is also very real: it can only spin in place or draw an arc, and cannot draw a beautiful turning trajectory like a real car. If you are building a racing car or need to avoid obstacles accurately, the differential steering is prone to overshoot or undershoot, and you need to perform PID compensation in the program. To put it bluntly, this is a solution that is adequate but not useful.
If you are coming into contact withservos for the first time, it is recommended to start with a 9-gram servo (such as SG90). It is cheap, lightweight, can work from 3.3V to 6V, and can be driven by direct connection to the board. The disadvantage is that plastic gears are not impact-resistant, and a few bumps may cause tooth damage. If you are building an off-road model, just install a metal gear servo, for example, although it is important, it is practical to use.
️ There is a pitfall here: many novices only look at the torque and ignore the dead zone width. The dead zone is the range where the signal changes but the servo does not respond. If it is too wide, the steering will be sluggish. Try to choose a model with a dead zone of ≤5 microseconds. Taobao generally does not write this on the details page. You can go to the official website to check the data manual, or directly search for "high-precision steering gear" to filter.
It's hard to say, but it's easy to say. In terms of hardware, you need to make a servo bracket, or just buy a U-shaped bracket with ears. There are only three connections - power, ground, and signal wires. Just don't plug them in backwards. What really takes time is adjusting the neutral position: you have to first send a 1.5ms pulse to reset the servo to zero, then manually straighten the wheel, and then lock the servo arm.
In terms of software, if you use it, the Servo.h library has already encapsulated PWM, and you can convert it by writing two lines of code. The only thing you need to pay attention to is the instantaneous current surge when the servo rotates. Do not share the same voltage regulator with the main control, as it is easy to reset. It is recommended to use a separate power supply, or use a large capacitor. I learned this trick from an old maker and it works repeatedly.
It looks really economical on paper: one costs more than 20 yuan, while a pair of TT motors plus wheels only costs more than a dozen yuan, and you can also save money on the servo bracket and ball joints. If you are doing science popularization for students, giving experience to children, or just need to verify the algorithm of mobile chassis, the servo-less solution is extremely cost-effective.
But if you include the cost of debugging time, the results may be reversed. The steering of a steering gearless car involves a complex differential algorithm. You have to repeatedly adjust the speed difference between the left and right wheels. If the friction on the ground is uneven, it will go directly off track. Although the hardware of the steering gear solution is more expensive, the control logic is linear and the code can be written almost once. To put it bluntly, what you save is money and what you waste is your hair.
My suggestion is very simple: for competitions or projects like racing, tracking, and path planning, choose a digital servo for fast response and high accuracy. For transportation, obstacle crossing, and robot arm linkage, choose a high-torque analog steering gear, which is made of durable materials. As for pure fun or tight funds, differential steering is completely sufficient, don't force it.
If you still want to know the real performance of servos at different price points, you can go to a certain creative community and search for "server evaluation". There are many open source projects that have posted waveform diagrams. You can also go directly to the brand's official website. For example, Huasheng and Huasheng have detailed selection guides. You will basically not be disappointed when buying based on the parameter list.
Having said so much, I would like to ask you: What is the most difficult thing for you about the car project at hand now: the price of the steering gear or the difficulty of debugging? Or maybe you already have a plan you like, but you’re just not sure if it can be implemented? Welcome to chat about your real situation in the comment area. I will pick a few typical questions and record a debugging video for everyone to see. If you find this article useful, remember to like it, save it, and forward it to your friend who is also playing with cars~
Update Time：2026-02-12
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