Testing the performance of a force sensor is crucial to ensure its accuracy, reliability, and suitability for specific applications. As a force sensor supplier, I've encountered various challenges and learned effective testing methods over the years. In this blog, I'll share some practical ways to test the performance of force sensors, which can help you make informed decisions when purchasing and using them.
Understanding the Basics of Force Sensors
Before diving into the testing process, it's essential to have a basic understanding of force sensors. Force sensors are devices that convert mechanical force into an electrical signal. There are different types of force sensors, such as strain - gauge sensors, piezoelectric sensors, and capacitive sensors, each with its own working principle and characteristics.
For example, the Flexible Film Piezoelectric Sensor SPE - 002 is a piezoelectric type sensor. Piezoelectric sensors generate an electric charge when subjected to mechanical stress. They are known for their high sensitivity and fast response time, making them suitable for applications where rapid force changes need to be detected.
Static Testing
Static testing is one of the most fundamental ways to evaluate a force sensor. It involves applying a known static force to the sensor and measuring the corresponding output signal.
Step 1: Prepare the Testing Equipment
You'll need a calibrated force - applying device, such as a dead - weight tester or a calibrated load cell. A multimeter is also required to measure the electrical output of the force sensor. Make sure all the equipment is properly calibrated to ensure accurate results.
Step 2: Mount the Sensor
Mount the force sensor securely on a stable surface according to the manufacturer's instructions. Improper mounting can lead to inaccurate readings due to misalignment or additional stress on the sensor.
Step 3: Apply Static Forces
Start by applying a small, known static force to the sensor. For example, if you're using a dead - weight tester, you can place a small weight on the sensor. Record the applied force and the corresponding output voltage or current from the sensor. Repeat this process with different forces, gradually increasing the force level up to the sensor's rated capacity.
Step 4: Analyze the Results
Plot a graph of the applied force versus the sensor output. The relationship should be linear within the sensor's operating range. Calculate the sensitivity of the sensor, which is the ratio of the change in output to the change in input force. Compare the measured sensitivity with the manufacturer's specifications. If there are significant deviations, it could indicate a problem with the sensor.
Dynamic Testing
In many real - world applications, force sensors need to handle dynamic forces. Dynamic testing is used to evaluate how well a sensor can respond to changing forces.
Step 1: Set Up the Dynamic Testing System
You'll need a dynamic force - generating device, such as a shaker or a solenoid. The shaker can generate sinusoidal or random force signals, while a solenoid can produce step - like force changes. Connect the force sensor to a data acquisition system to record the sensor's output over time.
Step 2: Generate Dynamic Forces
Generate a dynamic force signal with a known frequency and amplitude. For example, you can set the shaker to generate a sinusoidal force with a frequency of 1 Hz and an amplitude of 10 N. Monitor the sensor's output using the data acquisition system.
Step 3: Analyze the Response
Examine the sensor's output signal in the time domain and the frequency domain. In the time domain, check for any time delays or distortion in the output signal compared to the input force signal. In the frequency domain, use a spectrum analyzer to analyze the frequency response of the sensor. The sensor should have a flat frequency response within its specified bandwidth.
Let's take the Pressure Membrane Switch Force Sensor For Electric Blowpipe EBS02 - 2 as an example. This type of sensor is often used in applications where it needs to respond to quick force changes, like in an electric blowpipe. Dynamic testing can help determine if the sensor can accurately detect the force variations during the operation of the blowpipe.
Linearity Testing
Linearity is an important characteristic of a force sensor. A linear sensor has a proportional relationship between the applied force and the output signal.
Step 1: Apply Forces at Different Levels
Similar to static testing, apply a series of known forces to the sensor, covering the entire operating range of the sensor.
Step 2: Calculate the Non - linearity
Calculate the non - linearity of the sensor by comparing the actual output values with the values predicted by a straight - line fit of the data. Non - linearity is usually expressed as a percentage of the full - scale output. A lower non - linearity value indicates better linear performance.
Hysteresis Testing
Hysteresis is the difference in the sensor's output for the same applied force depending on whether the force is increasing or decreasing.
Step 1: Apply Increasing and Decreasing Forces
Apply a series of forces to the sensor, first increasing the force from zero to the rated capacity and then decreasing it back to zero. Record the output values at each force level during both the increasing and decreasing cycles.
Step 2: Calculate Hysteresis
Calculate the hysteresis as the maximum difference between the output values for the same applied force during the increasing and decreasing cycles, expressed as a percentage of the full - scale output. A low hysteresis value is desirable, as it indicates that the sensor's output is consistent regardless of the force application direction.
Temperature Testing
Temperature can have a significant impact on the performance of a force sensor. Temperature testing is used to evaluate how the sensor's output changes with temperature variations.
Step 1: Set Up the Temperature Chamber
Place the force sensor inside a temperature - controlled chamber. The chamber should be able to maintain a stable temperature within a specified range.
Step 2: Measure the Output at Different Temperatures
Set the temperature of the chamber to a low value, such as - 20°C. Apply a known force to the sensor and record the output. Gradually increase the temperature in steps, for example, every 10°C, and repeat the measurement at each temperature until you reach a high temperature, such as 80°C.
Step 3: Analyze the Temperature Coefficient
Calculate the temperature coefficient of the sensor, which is the change in output per degree Celsius. Compare the measured temperature coefficient with the manufacturer's specifications. If the temperature coefficient is too high, it could cause significant errors in applications where the temperature varies.
Conclusion
Testing the performance of a force sensor is a comprehensive process that involves multiple aspects, including static, dynamic, linearity, hysteresis, and temperature testing. By conducting these tests, you can ensure that the force sensor meets your application requirements.
If you're in the market for high - quality force sensors, we offer a wide range of products, such as the Flexible Film Piezoelectric Sensor SPE - 002, Pressure Membrane Switch Force Sensor For Electric Blowpipe EBS02 - 2, and Straight Flexible Thin Film Pressure Sensor - 120CM SPF03 - 120. Our sensors have been rigorously tested to ensure their performance and reliability. If you have any questions or need help with sensor selection and testing, feel free to contact us for procurement and further discussions.
References
- "Force Sensor Handbook" by Sensor Technology Ltd.
- "Measurement and Instrumentation Principles" by Alan S. Morris.