Intelligent robots and steering gears: detailed explanation of differences and connections (with frequently asked questions)

01Core definition: distinguish from the root

Automation equipment with perception, decision-making and execution capabilities is called an intelligent robot. It receives environmental information through sensors, processes information through chips or algorithms, and makes actions through motors, steering gears, etc. Home sweeping robots, industrial robotic arms, and toy robots are typical examples.

The steering gear is a position servo motor driver that can accurately control the angle of the output shaft. The angle range is usually 0-180 degrees or 0-360 degrees. It contains a DC motor, a reduction gear set, a position feedback potentiometer and a control circuit. When it receives a pulse signal, such as PWM, the servo will rotate and remain at the specified angle.

There is an effective memory method to distinguish between the two, that is, intelligent robots belong to the "whole" category, while servos belong to the "parts" category. The robot may not have a servo, such as using an ordinary motor, but the servo can only play its role if it is matched with a control system.

02Five Big Differences: Systems vs Components

The following is rewritten: The case is that the common small bipedal robot uses more than 10 servos, and these servos are used to control the legs. At the same time, these servos also control the arms respectively. Moreover, these servos also control the rotation of the head respectively. However, the robot is able to stand on its own. Moreover, the robot can walk on its own. Moreover, the robot can avoid obstacles, which is something that the steering gear alone cannot do. In another case, each joint of the industrial robot arm is equipped with a high-precision steering gear. The steering gear here is also called a servo motor. However, a complete set of robotic arms plus a controller and a vision system can be considered an intelligent robot.

03Core connection: The steering gear is the "joint actuator" of the robot

1. For intelligent robots that need to complete precise actions (such as robotic arms grabbing parts), ordinary motors have difficulties in angle control. The servo uses closed-loop feedback to achieve an accuracy within ±1° and provide precise operation.

2. Simplify the control design: The steering gear is equipped with a drive circuit and angle feedback. The robot's main control board only needs to output a PWM signal for control. There is no need to design additional motor drives and encoder reading devices.

3. Assemble through a modular approach. Among them, educational robots, competition robots and bionic robots often directly use standard servos, such as SG90, MG995 and other models, so that the joint structure can be quickly built.

4. The following is where the performance bottleneck lies: in terms of carrying capacity of the robot, the smoothness of the movement and the speed of the response are, in most cases, determined by the torque of the servo used, the width of the tooth gap, and the width of the dead zone.

In an actual scenario, when you start to make a relatively simple mechanical gripper, you will use two servos. One of the servos is specifically used to control the opening and closing movements of the gripper, and the other servo is responsible for controlling the rotation of the wrist. The servo itself does not have the ability to know what kind of object it wants to grab. However, after the robot uses the camera to identify the object, it will calculate the angle value at which the servo should rotate and then send a signal to let the servo perform the corresponding action. This entire process is a typical collaborative working mode.

04How to choose a servo according to the needs of the robot? (recommendations for action)

If you are designing or building an intelligent robot, please follow these steps:

Understand the required torque of the joints and estimate the load (in kg·cm) that each joint will bear. For example, if the end of a robotic arm is to lift an object of 0.5kg and the arm length is 20cm, then the torque needs to be at least 0.5 times 20 equal to 10kg·cm. The rated torque of the selected servo should be greater than 1.5 times the calculated value.

Determine the range of rotation angles: For commonly used servos, when the angle is 0 to 180°, it is more suitable for joints with multiple parts connected by hinges; for servos that continuously rotate up to 360°, it is suitable for wheels or rollers.

Considering the communication protocol, the three-wire interface of ordinary PWM servos is the most common. Bus servos, such as serial ports and CAN buses, are suitable for serial connection of multiple servos and can reduce the complexity of wiring.

Carry out work on evaluating response speed, in which high-speed servos (the time required to rotate 60° is 0.08 seconds) are used to achieve fast movements, while low-speed and high-torque servos are used for power joints.

It is emphasized again that the key word for steering gear selection is "leave a certain margin for torque, and check the backlash for accuracy." Metal gears are more wear-resistant than plastic gears. Compared with analog servos, digital servos have faster response times and stronger holding power.

05Frequently Asked Questions Q/A

Q1: Do intelligent robots have to use steering gear?

A: Not necessarily. Steering gear is suitable for precise angular control; if it only requires continuous rotation (like a wheel), it is cheaper to use a regular DC motor.

Q2: If the servo is broken, can the robot still work?

For A, it is impossible to perform actions that depend on the steering gear. If other structures are in an independent state, the robot can perform partial operations.

Q3: How to determine which part of the robot is the steering gear?

A: Check if there are three wires, one is red for the positive pole, one is brown for the negative pole, and one is orange for the signal, and it can rotate to a fixed angle and then stop.

Q4: Can the servo be used as an ordinary motor to rotate continuously?

A: The standard servo will not work. If it exceeds the angle range, it will get stuck or damaged. Use 360° continuous rotation of the servo.

Q5: Will controlling multiple servos interfere with the robot's main control?

(A) means yes. When the high-torque servo is started, the current is large, reaching 2A. It needs a separate power supply and cannot obtain power from the main control board.

06Repeating core ideas and final recommendations

It is clearly stated again: intelligent robots belong to the category of systems, and servos are components of them. Servos can give robots precise joint movement capabilities. However, in order for a robot to become "intelligent", it must rely on sensors, controllers and programs.. Whether you are a hobbyist or an engineer, please remember:

The starting point is the overall design. First, the task process of the robot must be defined, and then the corresponding steering gear parameters required for each joint must be calculated.。

Arrange the excess: Most of the torque marked on the servo is the value without load. In actual use, the amount needs to be reduced by more than 30%.

Test individual modules: Before assembling the complete robot, use Arduino or a similar development board to test the rotation range of each servo, test its response, and test its heating.

According to the above guide, you can quickly distinguish and properly match intelligent robots and servos to avoid common mistakes such as "buying the wrong parts" and "underestimating the complexity of the system."