PRESS Button Cycler Enhancements

The goal of the project is to update a button cycler system used in qualification testing of electro-mechanical switches on human-machine interfaces (HMI) designed by Advanced Input Systems.

=Problem Definition= Exhaustive testing HMI associated with dependable technology equipment is necessary to assure that they remain fully functional throughout the anticipated usage life. The goal of our project is to design a next-generation button-testing system and software package that can be easily configured to a broad range of keyboard and console geometries. The test will reduce human labor required for data acquisition and visualization as well as provide information about changes in switch health throughout the testing procedure.

Background
Advanced Input Systems develops HMI, such as keyboards, consoles and smart surfaces, for a broad range of applications including military and medical devices. Some of these devices are vital to human health and safety, so it is extremely important they know how long each of their switches is guaranteed to last without failure.

To determine this, AIS uses a system with the following capabilities: System drawbacks to be considered:
 * Incremental counters detect and display the number of switch closures since last reset.
 * Bimba force can be controlled somewhat by adjusting input pressure.
 * Multiple air cylinders (Bimbas) can be used to test multiple keys on a device.
 * No way to monitor or accurately adjust force applied by Bimbas.
 * No way to measure or quantify switch health.
 * Switch closure count does not indicate when and error has occurred.

This final point is most important. The cause and context of each switch failure is crucial information when determining the life expectancy of a button.

Deliverables
Four levels of priority were initially assigned to the product design:

Priority 1: Necessary for product prototype
 * An apparatus and LabVIEW program which emulates the current system capabilities, as well as provides switch debounce detection and meaningful datalogging.

Priority 2: Preferable but Optional
 * Incorporate Bimba force detection and user input for force selection.

Priority 3: Optional
 * Incorporate in situ switch characterization using force/displacement/resistance hysteresis curves to monitor switch health.

Priority 4: Preferable for future product
 * Modernize hardware setup for final button cycler system.

During early development, priorities 1-3 were considered. Due to the learning curve for LabVIEW development, priority 1 became the entire scope of this year-long project.

Specifications

 * The following is a list of [[Media:2019_PRESS_ProductRequirements.pdf|Product Requirements]]

=Design Considerations=

The first test bench was modeled and built to mimic one Bimba on a single gantry rail from the current AIS system. It was designed to accommodate up to six Bimbas for later testing phases. Bimbas, their mounts (machined as AIS), and the rail were supplied by the client. The rail mounting fixtures and keyboard tabs were 3D printed with PETG filament (for strength and simplicity). Hardware was purchased through McMaster-Carr and local hardware stores.

The first step in the product design was to ensure that the current AIS system could be emulated and sufficient data could be collected. In order to bootstrap experimentation while equipment was on order, an Arduino setup was built into the first DOE in place of LabVIEW and a DAQ. This presented opportunities to design and improve the pneumatic system components.

A solenoid valve was used to control the actuation of each Bimba. In order to allow higher cycle rates and reduce noise from the return strokes, output valves were fitted to each solenoid to control Bimba back pressure. A regulator tank was employed to maintain consistent pressure values. The test bench hardware will currently support four Bimbas.

Further consideration will be taken to ensure the gantry rail can withstand max load from multiple Bimbas once the software supports a multi-button system.

=Project Learning=

=Final Design=

=Validation=

=Team Members=

=Additional Documentation=

[[Media:2019_PRESS_ValueProposition.pdf|Value Proposition Statement]] [[Media:2019_PRESS_Schedule.pdf|Project Schedule]] [[Media:2019_PRESS_Budget.pdf|Project Budget]] [[Media:2019_PRESS_TeamContract.pdf|Team Contract]]

[[Media:2019_PRESS_MeetingMinutes.pdf|Meeting Minutes]]

[[Media:2019_PRESS_ProductRequirements.pdf|Product Requirements Document]]

[[Media:2019_PRESS_P1_BOM.pdf|Priority 1 System BOM]] [[Media:2019_PRESS_P1_SystemDiagram.pdf|Priority 1 System Diagram]]

Presentations

[[Media:2019_PRESS_DesignReview_Presentation.pdf|Design Review Presentation]] [[Media:2019_PRESS_Snapshot1_Printouts.pdf|Snapshot 1 Printouts]] [[Media:2019_PRESS_Snapshot2_Printouts.pdf|Snapshot 2 Printouts]] [[Media:2019_PRESS_EngrReleaseReview_Presentation.pdf|Engineering Release Review Presentation]]