How to choose a micro steering gear? Teach you to choose the one that suits you best

01Just look at the nominal "kilograms"

First, you need to pour a basin of cold water, and you conduct an Internet search for "best sub microservo", "2.5kg torque" and "0.07 seconds speed" are everywhere on the screen, but the price difference is up to ten times. What's going on? Come on, conduct a small experiment and select two servos with the same parameters. One of them is in Pinxixi I bought it at a price of 9 yuan with free shipping. The other one is a regular product with the same 50g weight arm hanging on it. The 9 yuan one started to "nod and tremble" as if it was suffering from an eating disorder, while the regular one remained motionless and as stable as an old dog.

Why? This is because the nominal value is "locked rotor torque". This data is measured under ideal voltage, room temperature environment, and extremely small backlash of the servo. The motor magnets used in those cheap products are very likely to be made of ferrite instead of NdFeB, and their gears are injection molded from recycled plastic. How can the measured data be the same? So, please forget about that number, and look at the actual test situation, and look at what the disassembly and analysis is like. This is the only real reason for the student party to avoid the big pit - this is the first "prompt word for article writing": You may ask, what should we look at if we don't look at the parameters? It depends on word of mouth and actual cases of peers.

02Gear material: metal or plastic? This is a "sending proposition"

This is also where novices struggle most. Do metal teeth sound high-end and classy? Yes, but not entirely correct.

The advantage of plastic teeth (nylon/polyoxymethylene) is that they are quiet, have smooth performance, and will not cause damage to the output shaft (when the force is too strong, the teeth will sweep first, thus protecting the downstream structure). The disadvantage is that it does not have the ability to withstand impact. Once your rough-running robotic arm program crashes, the teeth will become flat with a click.

The advantage of metal teeth is that it has a high bearing capacity and can withstand a large load. The disadvantage is that it is more expensive, there is a certain gap and a virtual space position, and it produces a lot of noise during operation. In the event of a jamming situation, it is very likely that the motor or the servo mainboard will be burned.

Let’s draw a conclusion: if you want to make a desktop mini robot arm or a fixed-wing aircraft rudder, metal teeth are crucial. If you are making a lightweight car steering device or a small bionic robot leg, high-quality plastic teeth are enough and can even save you the cost of a canteen meal.

There is such a very common case. There is a team participating in a smart car competition. Out of greed for cheapness, all the cars use metal gear servos.. However, after a minor collision, something like this happened. The steering gear was not damaged, but the plastic steering cup was broken. This situation caused the mentality of the entire team to collapse instantly.Then it was replaced with a plastic gear servo. When the same collision happened again, the servo showed tooth sweeping, but it played a role in protecting the structure. Just replace a gear set worth only a few dollars, and the vehicle can be restored to its original state.. Then take a look, isn’t that how value recognition comes about? What you really need is for the entire system to be in a stable state, rather than the "hard" appearance of a single part. Don’t fall into the cycle of excessive competition in parameters. The appropriate one is the best. This second "article writing tip" is about to appear: you may be thinking, how do I determine exactly?

03Voltage and Dead Zone: What the Data Sheet Doesn’t Tell You

Thinking across different regions, if you buy a steering gear in a humid storage warehouse in Guangdong, and then send it to a parking warehouse in the Northeast where the temperature is as low as minus 20 degrees, will the performance still be the same? That's absolutely not the case.

The power of the servo is voltage. The torque of the same Taiwanese servo will differ by 40% under 4.8V and 6.0V conditions! If you feed it a "step-down" condition (for example, when drawing power from USB, the voltage will drop to 4.5V), then don't think about it being able to do heavy work.

The "slow response" of the servo to signals is the dead zone. The cheap sub microservo, its dead zone can reach 10 microseconds (μs), and when a fine-tuning instruction is sent to it, it will either remain motionless or overshoot. A good one can usually hit it within 2μs, and it can hit exactly where it is pointed. How to measure it? This is very simple. Connect the receiver and use the remote control to perform fine-tuning operations one by one. Check whether the servo arm moves correspondingly with the manually set fine-tuning value every time.If the servo arm does not move correspondingly with the manually set fine-tuning value, it will affect the use effect, and it will undoubtedly have to be returned.。

The advice given by the action is not to believe the instructions, but to conduct tests yourself. Use an adjustable regulated power supply to supply power to the servo from 4.8V to 6.0V. Hang a simple tension gauge, even a spring scale, to record the actual force given. Doing this won't take you half an hour, but it can screen out 80% of "parameter cheats".

04Frequently Asked Questions Q/A Quick Questions and Answers

Q1: Why does the servo always make a "sizzling" sound?

Step 1: A shows that there is such a conclusion. It is in a state of looking for the midpoint, but it cannot be found. Step 2: You need to check whether the external load is too large, or whether the servo arm is installed too tightly, or whether there is interference.

Q2: My servo is burned out and smells like paste. Is there any way to help?

A came to the conclusion that there is a high probability that the core PWM drive tube or motor coil is burned out. Don't try to save it. Just replace it with a new one. Otherwise, there is a high probability that the motherboard will be burned out.

Q3: To power the servos, can batteries be directly connected in parallel?

A: Conclusion: It can work, but the voltage must be kept stable. It is recommended to use a BEC (that is, a voltage stabilizing module) to limit it to the rated voltage range. Otherwise, letting a fully charged battery directly drive it is undoubtedly equivalent to "murder".

Q4: Can plastic teeth and metal teeth be mixed in one structure?

Conclusion: You have the ability, but the purpose must be clear. As a component that acts as a "fuse" for torque output, it is a wise design to use plastic teeth in joints that are easily damaged and metal teeth in other parts.

Q5: How to simply judge whether the servo is "centered" or not?

A: The conclusion is, give the 90-degree neutral signal, break the servo arm with your hands, and see if it can achieve perfect return after releasing it.. If it cannot return to the position or is shaking, it means that the center is back to bad, and this situation needs to be abandoned decisively.

Seeing this, as smart as you are, you should have already understood. Known as "best sub micro servoThere is no permanent first place for "things", only the one that best suits your current project, current budget and even the current experimental environment. Stop being a stickler for parameters and become a practical practitioner. This last "Tips for Article Writing" is given to you: You may be curious, why do I reiterate these seemingly tricky verification measures again and again? When you actually solder the board and execute the code operation; when you watch the servo elegantly achieve the intended action. , you will find that the time you spent worrying about everything and paying special attention to it in the early stage was worth it.However, those cheap servos that you grab will eventually become "electronic waste" placed on your desk. It will teach you to re-understand the word "value" in a way that silently pays a relative cost.。

To this end, please keep in mind: one penny will get you something, two cents will get you two cents, and three dollars will get you three cents. In this market, the long-lasting rule is whether you pay a hidden tuition fee for your lack of knowledge, or pay a clear price for the solidity under your feet. Take action, don't just fantasize.