PRESS Button Cycler Enhancements

The goal of the project is to develop enhancements to a button cycler for use in qualification testing of electro-mechanical switches designed into Advanced Input Systems’ products.

=Problem Definition= Exhaustive testing of human machine interfaces (HMI) associated with high technology equipment is needed to assure that the HMI remain fully functional throughout the anticipated usage life. The goal of our project is to design a next-generation keyboard testing equipment/software package that can be easily configured to a broad range of keyboard geometries. The test will reduce human labor required for data acquisition/visualization and provide information about changes in switch health throughout the entire testing procedure.

Background


The current system at AIS has the following capabilities: System drawbacks to be considered:
 * Incremental counters detect and display the number of switch closures since last reset.
 * System 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 pneumatic Bimbas.
 * No way to measure or quantify switch health.
 * Switch closure count does not indicate when and error has occurred.

Deliverables
The four levels of priority assigned to the product design are as follows.

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.

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]]