2-Axis Automated Button Presser

Simplexity Product Development Sponsored Project

Project background

The 2-axis automated button presser was sponsored by Simplexity, which is a company located in San Diego, CA, devoted to design next generation products for leading technology companies. Simplexity aimed to test the fatigue life of buttons on its designed products for ensuring the quality. Hence, this project was created to design a mechatronic device that could mimic customers’ button-touching actions. Additionally, the project’s intent was to demonstrate the capability of Simplexity’s in-house motion control board. Beyond the office in San Diego, the sister office in Vancouver, WA started a similar project at the same time; and two projects would compete with each other at the end of this project. The top priority of this project was to finish the mechanical design of this device, including achieving the two-axial horizontal motion automation and the variable force output from the presser. The development of firmware and software was a secondary priority. 

High Priority Objectives

The button presser should be able to:

• Achieve horizontal 2-axial automated motion

• Apply variable forces (1-10 N)

• Fit products of different sizes and shapes

• Test buttons for twenty millions of times within a period of six months

Second Priority Objectives

In addition to design a functional button presser, several additional features could be added:

• A presser that simulates the finger touch

• Demo python script that can demonstrate the horizontal 2-axis motion

Other Constraints and Issues

• NO INJURY. One user can easily operate the device without getting hurt

• Total costs should not exceed the budget

• Capability of running a million cycle before maintenance

• Reduction of electrical noise

• The button presser should stop working when tested button fails

Deliverables 

The following are the deliverables according to the requirement from the sponsor

1. Integrated button presser system

• Automated horizontal motion system

• Manual z-axis lift system

• Product holding platform

• Presser with variable force output along with

• Bill of Material (BOM) and reproduction instruction

• Operation instruction and test plan

• CAD model and 2D drawings of custom components

2. Embedded motion control board

• Demo Python script that can control the motion of pressers

• Firmware circuit schematic drawing

Design

Final Design

The final design of this device contained:

• • ·    Timing-belt-driven two-axial motion guides with aluminum gantry

  • ·    A product holder on a scissor lift

  • ·    A cam-spring coupled presser

The motion stage gantry was manufactured using a stepper-motor-driven timing-belt motion guides and aluminum materials. The presser was mounted on Y axis motion stage. Optical sensors were installed for homing motion stages.

The product holder was designed to constrain products of different sizes and shapes.  The size of the holder was adjusted by rotating the handwheels, driving two walls until the product was held still. The leadscrew-driven scissor lift under the platform changed the height to accommodate test samples in different thickness.

The cam-spring coupled presser applied variable forces when the cam rotated. The contour with changing radius compressed the spring connected to the finger to different lengths, which applied forces from 1N to 10N on the tested button.

The motion control board, provided by the sponsor, was capable of controlling the stepper motors, the brushed DC motor, and homing sensors.

Tests

The tests of the motion guides, product holder, scissor lift, and  pressers were performed. For the motion guides, under different microstep settings of the stepper motors used, the precision and speed of the stages were measured which was the top priority. The precision was 0.003 m under all microstep settings.

The product holder test result showed that products within 0.09 m × 0.085 m to 0.206 m × 0.201 m. Then, the scissor lift test indicated that the maximum height change was 0.25 m. For the force test, the output forces varied from 0 to 8.8 N with an average error of ± 0.4 N.

Overall, this project designed and manufacture a 2-axis automated button presser for testing buttons. This process provided a valuable reference for the sponsor to further improve the firmware of the motion control board. Also, this device could introduce reliable products to daily life, save people’s lives during emergencies, and reduce replacement and waste. In short, this project helped guarantee the quality of buttons on various products.

Task Distribution

Sponsor

Neil Foxman, Mechanical Engineer

Simplexity Product Development

Website Manager, Mechanical Design

Rong Bao

Fiscal Manager, Paperwork Manager, Mechanical Design, Manufacture

Yiren Shao

Sponsor Liaison, Mechanical & Firmware Design, Manufacture, Programming

Yueqi Wang

Safety Manager, Mechanical Design, Manufacture

Yingzhi Yang