In university robot competitions, encoders, as an important sensor device, are widely used to measure the position and movement of robots, providing accurate data support for robot control systems. The following is a detailed introduction to the encoders used in university robot competitions:

1、 Basic principle of encoder

An encoder is a device that converts mechanical motion into electrical signals. It converts the displacement or rotation angle of an object into a measurable electrical signal output. These electrical signals can be read and processed by robot control systems to achieve precise position control, speed control, and trajectory tracking functions.

2、 Types of encoders

In university robot competitions, common types of encoders include:

Optical encoder:

Principle: Utilizing the photoelectric effect for displacement measurement. When the light beam emitted by the light source passes through the transparent and opaque lines on the encoding disk, the photosensitive element will receive the light pulse signal and convert it into an electrical signal output.

Features: High precision, high resolution, strong anti-interference ability. Suitable for application scenarios that require high precision, such as precision assembly, welding, etc.

Magnetic encoder:

Principle: Use magnetic field changes for position measurement. The rotating component of magnetic materials changes the distribution of the surrounding magnetic field when it rotates, and the magnetic sensitive component can detect this change and convert it into an electrical signal output.

Features: Strong environmental resistance, simple structure, low manufacturing cost. Suitable for applications in harsh environments with high levels of dust, oil, and water.

3、 The Application of Encoders in Robot Competitions

Position control:

Encoders can accurately measure the position information of robot joints or actuators, providing precise position feedback for control systems. By real-time monitoring and comparing the actual position with the expected position, the control system can adjust the robot's motion trajectory to ensure that the robot can accurately reach the predetermined position.

Speed control:

By detecting the frequency of the pulse signal output by the encoder, real-time speed information of the robot joints or actuators can be calculated. The control system can adjust the input voltage or current of the motor based on the speed feedback signal to achieve precise speed control. This is of great significance for maintaining the stable motion speed of the robot and avoiding overspeed or low-speed operation.

Trajectory tracking:

In robot competitions, robots are often required to move along predetermined trajectories. The encoder can provide the current position and speed information of the robot, and the control system calculates the deviation between the robot and the predetermined trajectory based on this information, and adjusts the motion parameters of the robot to enable it to accurately track the predetermined trajectory.

Fault diagnosis and maintenance:

Encoders can also be used for fault diagnosis and maintenance of robots. By monitoring the output signal of the encoder, it is possible to determine whether there is abnormal motion or damage to the robot joints or actuators. Once a fault is detected, the control system can issue corresponding alarms or shut down for timely maintenance and replacement.

4、 Considerations for Encoder Selection

When choosing an encoder, the following factors need to be considered:

Accuracy requirement: Select the appropriate encoder type based on the accuracy requirements of the competition task. For tasks that require high-precision measurement, photoelectric encoders or absolute encoders should be selected.

Environmental factors: Consider the environmental conditions of robot competitions, such as temperature, humidity, dust, etc. In harsh environments, encoders with strong environmental resistance, such as magnetic encoders, should be selected.

Cost budget: The cost of different types of encoders varies greatly. It is necessary to choose the appropriate encoder type based on the competition budget and team economic situation.

Usability and maintenance: Choosing an encoder that is easy to install and has low maintenance costs can reduce later maintenance work and improve competition efficiency.

5、 Example application

In robot competitions such as "ROS Intelligent Car Autonomous Driving", encoders are widely used for measuring the wheel speed and steering control of the car. By installing photoelectric encoders or magnetic encoders on the wheels and steering shafts of the car, real-time monitoring of wheel speed and steering angle information can be achieved. The control system calculates the actual motion state of the car based on this information and adjusts the input parameters of the motor to enable the car to move according to the predetermined trajectory and speed.

Overall, encoders play a crucial role in university robotics competitions. By selecting the appropriate encoder type and reasonable installation method, precise data support can be provided for the robot control system, achieving accurate position control, speed control, trajectory tracking and other functions, improving the robot's performance and stability in competitions.