What functions does the steering gear implement? The three core competencies are explained clearly at once

At 11 o'clock in the evening, the sorting robot in an automated warehouse suddenly "strike".

The robotic arm froze in mid-air, and the courier box it grabbed was teetering.

The engineer conducted an emergency investigation. After the investigation, they finally discovered that there was a steering gear responsible for wrist rotation, and the angle feedback signal of this steering gear had been completely lost.

What mission does this component, which is not much larger than a matchbox, carry?

To answer this question, we must first figure out:What are the functions implemented by the steering gear?。

If you are in a state of distress and frustration when choosing a model for automation equipment, or if you want to understand why this thing called a "small joint" can have a leveraging effect on a large system, then the content presented next will give you a clear answer.

Core function one: Angle control within millimeters

The most fundamental ability of the steering gear is to accurately position the angle.

It has an angle sensor inside, which is either a potentiometer or a magnetic encoder. It is like an eye that is always open, always staring at the position of the output shaft.

When the control system issues an instruction, which is "turn to 45 degrees", the servo will start the comparison action. The comparison objects are the current angle and the target angle. Finally, the servo will start such a comparison.。

Once a deviation is detected, it prompts the motor to quickly adjust until the error is reduced to within 1 degree.

The case of a smart security company is very convincing.

They have deployed 200 spherical cameras in the large park. Each camera must continuously patrol 80 predetermined monitoring points 24 hours a day. This arrangement is required.

If the position of the servo is not accurate, the camera will shift a few degrees to the left or right every time it is parked, and the key area will become a blind spot.

So what is the result? After replacing it with a high-precision servo, the surveillance picture has been extremely stable. The security captain has never received a complaint such as "half a door is missing from the east picture."

You see, without precise angle control, the so-called automated monitoring is just empty talk.

In this way, apart from being able to make the robotic arm accurately hit the designated position, what other aspects does the servo achieve? The second ability is equally indispensable.

Core function two: speed control with a degree of relaxation

Speed ​​control is another underrated skill of the servo.

Many people think that the steering gear only cares about "whether it reaches the position", but they ignore the importance of "how to reach the destination".

Imagine that in the filling production line of a pharmaceutical factory, the mechanical hand has to pick up the medicine bottles from the conveyor belt and place them on the inspection table next to it.

There is a conveyor belt that moves 30 centimeters per second. If the speed of the robot is suddenly fast and slow, it will either catch empty bottles or knock down a row.

The speed adjustment function of the steering gear allows engineers to set a "uniform motion curve". From the start to the stop, the entire process is as smooth as silk sliding across people's fingertips.

Even better, speed control often works in conjunction with position control.

An integrator engaged in logistics sorting told us that when they used ordinary servos, packages would often fly out of the box due to emergency stops. Later, they switched to servos with speed closed loops. After that, the manipulators were like experienced acrobats, able to control the speed freely, as fast or slow as they wanted, and the damage rate was directly reduced by 60%.

To put it another way, if the servo can only perform positioning but cannot adjust speed, then it is like a carpenter who can only use brute force to smash nails. The work can be completed, but no one is willing to pay the labor.

Core function three: Torque output with both rigidity and softness

The third function is the most easily overlooked but crucial, it is programmable torque output.

Torque, in layman's terms, is the "power of rotation" of the steering gear.

Traditional steering gear often works with maximum strength, no matter it is facing an egg or an iron block.

But modern scenarios require more nuanced interactions.

A prosthetic research and development team encountered a problem. The robot hand they built could effortlessly pick up dumbbells, but when holding eggs, it always crushed the eggshells.

What's the problem? The torque output by the steering gear is constant, and changes in force cannot be sensed.

Then, they switched to a steering gear with a torque limit support function and set the next safety threshold. Once the resistance exceeds the corresponding force that the egg can withstand, the steering gear will stop increasing the torque on its own.

The results gave a surprising display. The robot hand has the ability to hold an egg, and it can also gently pick up a piece of tofu without leaving any scratches.

The same logic applies to collaborative robots. When workers approach the running robotic arm, the torque feedback function of the steering gear can instantly detect abnormal resistance and then stop the operation or move in the opposite direction to prevent harm to people.

It's like putting a "tactile skin" on the machine.

If there is no torque control, all automation equipment will become dangerous and slow, either afraid to use force or not knowing the convergence limit.。

How do the three major functions work together?

Now, let's put the three functions together.

What angular position it is in determines the "specific place to go", how the speed is controlled, which determines the "way of travel adopted", and what kind of output the torque gives, which determines the "amount of force exerted"。

A complete steering gear must handle these three things at the same time.

Take a domestic remote control model car as an example. When cornering at high speed, the servo must quickly turn to a specified angle, which is speed control. It must also stop accurately at the corresponding position of the steering wheel, which is angle control. The output strength must be automatically adjusted based on the friction between the tire and the ground, which is torque control. Otherwise, the car will push or drift.

Lao Zhang, a model player, made a very practical statement, saying that the performance of a normally usable steering gear does not only depend on its torque value, but also needs to consider whether it can simultaneously have the three characteristics of fast speed, accurate positioning and stable operation when it is operating under a certain load.

It is the three superpositions of these capabilities that make the small steering gear an indispensable "joint" in the field of robotics, even in the field of drones, even industrial automation, and even the field of medical equipment.

Frequently Asked Questions (Q/A)

Q: Can the servo rotate continuously 360 degrees and be positioned at any angle?

First of all, A means no. The reason is that the angle limit of the standard servo is in the range of 0 to 180 degrees. Then, the servo can only control the speed and direction of 360-degree continuous rotation, but it cannot position the angle. This is the actual situation.。

Q: What are the essential functional differences between digital servos and analog servos?

A: The response speed of the digital servo is getting faster and faster, the positioning accuracy is further significantly improved, and the holding torque is relatively larger. The reason is that the internal processor drives the motor at a higher frequency.

Q: Will the angle of the servo deviate under load? How to solve it?

When the steering gear is loaded, angular errors will occur, resulting in deflection. When operating in high-precision scenarios, it is necessary to use a steering gear with a closed-loop encoder or magnetic encoder to achieve real-time correction of angular errors.

Q: How to judge whether the steering gear is suitable for long-term continuous operation?

Look at the heat dissipation design first, and then the rated current. Continuous operation will cause temperature rise. The metal shell and active cooling fan are key indicators.

Q: How many times can the life of a servo be reached?

A high-quality servo can be used more than 100,000 times under reasonable load conditions, while the plastic gear version of the servo can be used usually less than 50,000 times.

Decision list for you

Now, you already know what the three core functions of a servo are.

Going back to the story about the warehouse robot told at the beginning, the engineer finally replaced the steering gear and re-calibrated the angle feedback curve, and then everything returned to normal.

This lesson tells us: Don’t just look at price or a single parameter when choosing a servo.

The next time you are faced with a selection form, please check these three questions:

Does my app needSub-degree angular accuracy？

Does my movement trajectory requireSmooth speed transitions？

Does my device requireSense and adapt to changes in external forces？

If the answer to all three is "yes", then don't hesitate to invest in a fully functional steering gear. It is much more cost-effective than repairing the losses caused by ten downtimes.

After all, in the world of automation, every degree of control, every second, and every meter of control ultimately lead to the same goal - to make the machine truly sensible, rather than just capable of being active.

The steering gear is the smallest unit for this goal.

Get it right and the whole system is half won.