Application case of integrated stepper servo motor in test tube liquid detection equipment

In the field of medical testing equipment, in vitro liquid testing requires extremely high motion control accuracy and stability. This device utilizes STM57 and STM42 integrated stepper servo motors and implements high-precision positioning control via the CANopen communication protocol, eliminating the positioning jitter associated with belt drive systems and providing an innovative solution for improving the reliability of motion control in medical testing equipment.

1. Device Overview

This in vitro liquid testing device is primarily used for testing liquid samples in the medical industry. Core requirements include:

1. Positioning Accuracy: High-precision positioning is required to ensure accurate test results.

2. Functionality: A home return is required upon power-up, and position mode positioning is supported.

3. Stability: Reducing settling time to prevent jitter from affecting the testing process.

2. Application Solutions and Products

(1) Core Product Configuration

• Motor Model (Short-distance Positioning): STM57B5B-CANopen-M

• Motor Model (Long-distance Positioning): STM4260B-CANopen-M

• Control Mode: CANopen communication protocol, position mode positioning

(2) Technical Optimization

• Acceleration/Deceleration Optimization: Slow acceleration/deceleration for short distances, high acceleration/deceleration for long distances

• PID Parameter Adjustment: Reduced settling time and improved positioning stability

3. Problems and Solutions

ProblemCauseSolutionProblem 1: Positioning JitterBelt drive structure causes positioning jitterAdjusted acceleration/deceleration parameters: slow for short distances, high for long distancesProblem 2: Long Time to PositionExcessive positioning settling timeOptimized PID parameters to reduce settling time

Implementation Results:

• Positioning stability is significantly improved, and jitter issues are largely eliminated;

• Settling time is shortened, improving inspection efficiency.

4. Application Results

1. Inspection Accuracy: Positioning accuracy meets medical inspection requirements;

2. Reliability: Equipment operational stability is significantly improved;

3. Compatibility: Perfectly compatible with the customer's existing control system.

5. Summary

This case study resolved positioning jitter and long positioning times caused by belt drives in test tube liquid testing equipment by optimizing acceleration and deceleration parameters and PID tuning. This solution demonstrated:

• The importance of acceleration and deceleration parameters for positioning stability;

• The key role of PID tuning in reducing settling time.

It provides the following insights for motion control in the medical testing equipment field:

• Belt drive structures require special attention to acceleration and deceleration parameters;

• PID parameter tuning should be tailored to actual motion requirements;

• The high reliability of the CANopen communication protocol in medical equipment.

Future applications can be expanded to other high-precision medical testing equipment.