Human Machine Interface Test

With Nibe - Sustainable Climate Solutions

The Problem

Nibe had designed a new Human Machine Interface (HMI) device which needed to be tested using existing ADDQ Test Stations. This HMI used a touch screen to receive inputs and display information to users. Testing this physical interface is difficult with units loaded into a fixture that needs to guarantee operator safety and fast cycle times.

The Solution

QESTIT designed a test fixture which works with an existing test station already used at Nibe. The fixture included a camera vision system and linear actuators for reading/pressing the UUT.

Test Fixture in Station

Units Under Test in Fixture

Test Fixture in Station

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This test fixture is similar to other fixtures we have produced for Nibe and uses the same hardware to record measurement results. You can see more about that test system here.

The main challenge of this project was constructing a system which could verify several HMI features, while the HMI unit was placed inside of the fixture. The features could not be verified in a conventional way - for example by reading test point voltage - and were often based on physical stimuli (like touch or sound). These included:

Verifying the screen displays different colors
Verifying the display backlighting in various conditions
Verifying the RF and Zigbee capability of the HMI device
Verifying buttons on the HMI worked when pressed
Verifying the UUT outputted a sound at the correct point during testing

To solve these problems we implemented a vision system for seeing light/colors. Installed mechanical actuators to press buttons, microphones to measure sound, RF sensors and installed lamps inside of the fixture lid. Some of these solutions have been implemented in other projects and thanks to our test platform QATS, we could quickly implement the previous code. It also meant that installing new hardware, drivers and code control snippets was a simple and quick process. This is because QATS operates with a plugin architecture, allowing us to 'plugin' or 'unplug' code quickly.

Pictured: Safety rods with soft tips for screen protection, a system controlled lamp and viewing hole for the camera

Pictured: VPC interface between the station and the fixture

Microphones were installed inside of the fixture and within the vicinity of the UUT. RF sensors were placed on top of the fixture to capture RF/Zigbee data. All additional hardware connects to the test station through an industry standard VPC interface. This means that the fixture can easily be 'plugged' or 'unplugged' from a station without disconnection a series of cables. This has some clear benefits including reducing downtime when changing UUTs, preventing operator risk and an overall reduction of cost.

"We use QESTIT because we need your competence and experience...We also appreciate the straightforward and simple communication in our projects."

Staffan Gustafsson, Project Manager, Nibe

Some additional system highlights include the mechanical lever component used to connect the power and communication pins to the unit. These pins sit perpendicular to the test point pins located on the underside of the unit. Therefore an additional pin mechanism was needed to connect/disconnect those pins.

Operators could scan units using a wireless barcode scanner which connected to a PC located in the test station chassis.

Pictured left to right: RF antennas/linear actuators, mechanical lever component, wireless barcode scanning

Summary

The project is currently being used to test a new generation of HMI units and is used in batch production. This project demonstrates the flexibility of our QATS platform and the range of different features our stations can have.

See more about what Nibe do here.