PinPad: Touchpad Interaction with Fast and High-Resolution Tactile Output

Jingun Jung, Eunhye Youn and Geehyuk Lee

 
  We explored new interaction scenarios that can be realized when a touchpad outputs fast and high-resolution spatio-temporal tactile patterns to the touch-sensitive skin on the fingertips of a user. We first constructed a special tactile multi-touch touchpad called PinPad, which was capable of outputting fast and high-resolution tactile patterns using a 40 × 25 array of actuated pins. We then developed various interaction scenarios that could be realized using the prototype: 1) Tactile Target, 2) Guide and Constraint, 3) Multi-finger Output, and 4) Dynamic Partition.

  To evaluate the PinPad scenarios, we implemented demo applications, and conducted interviews with users to collect feedback about their experiences with PinPad and the PinPad scenarios. The participants confirmed the effectiveness of spatio-temporal outputs of PinPad in the scenarios. In particular, they provided diverse feedback regarding the unique tactile experiences of the fast and high-resolution outputs of PinPad.

 

 

Hardware

System

pinpad-1
  • (a) The Braille module. It is from metec AG .
  • (b) The overall structure. There are 40 x 25 modules. We used two Arduinos: one is for touch sensing, the other one is for Braille control. There are two PCBs: one has touch electrodes which is covering the modules, the other one is backplane board which control the Braille modules.
  • (c) The system block diagram.

 

Circuit Schematics and PCBs

Touchpad

  • Touchpad Electrodes Schema
    This is schema file for touchpad electrodes. The red part is vertical electrodes lines and the blue part is horizontal lines. These parts are overlapped each other. The board .brd file is below.
  • Touchpad EAGLE .sch and .brd files
    This is a zip file of .sch and .brd file for touchpad electrodes. You can read these file using EAGLE program and reproduce the electrodes circuit.
  • Paper insulator .ai file
    We used two sheets of black paper as an insulator. The paper is an ordinary black A4 paper in a store. Two papers were attached by adhesive for temporary fixing. We cut the paper using laser cutter in our lab. The diameter of the hole was determined not to interfere with pin entry and exit.

Backplane board

  • Backplane PCB schema
    Backplane board is used to control braille cells. The bottom right part is for arduino which is programmed for Braille Arduino code below. The top right part is for 200 V voltage chip. And the top center part is for shift registers to transfer signals to braille modules.
  • Backplane PCB gerber
    This is gerber explanation of the backplane board which you can refer to.

 

Arduino Codes

  • Touchpad Arduino code
    The xy data from the Arduino has the header ‘yy’ and the size of data is 36. We used the serial communication with an Arduino Leonardo.
  • Braille Arduino code
    Arduino code to send control signal to backplane board. Five data pins are for each horizontal line of braille module. Latch signal is for shift register which choose vertical line among 20 lines.

 

Windows Interface

  • Touchpad client
    This PC software is used to receive the x-y data from Arduino. The x-y data is calculated in the IQS550-B000 and the Arduino is used to transmit the data to the PC. In this software, you can see the x-y data when you check the checkbox ‘GUI Enable’
  • Pinpad scenario client
    This Windows application is to test scenarios of PinPad. There are 6 scenarios applications implemented.

 

Reference

  • Azoteq touchpad module datasheet
    We used IQS550 as a touch sensor. It can sense 15 X 10 touch electrodes, so finally we got 1028×768 touch resolution. For the IQS550-B000 version used by our latest PinPad hardware, Azoteq provides PC software to tuning variables like a touch threshold, proximity sensing threshold in the firmware. Using the flash programmer they also provided and the debugger, the final setting in this PC software can be uploaded directly to the IQS500-B000 chip. We used them to tuning our touch sensing. We set the ATI value to the 0 after the inquire to the software developer of Azoteq via email.
  • Braille module datasheet
    We used 100 modules of D2-S from metec AG. Bits pins relation and other specifications are in the datasheet. The module require 200V voltage. So DC-DC converter is needed.

 

Publication

  • PinPad: Touchpad Interaction with Fast and High-Resolution Tactile Output
    Jingun Jung, Eunhye Youn and Geehyuk Lee, CHI 2017.