David Meyer

David Meyer's picture
Alumnus

Tech B230

Year graduated: 
2015
Former Position/Degree: 
Ph. D.

My specific areas of interest include teaching, electronics and embedded systems, and haptic devices.  In my free time, I enjoy brewing beer, camping, and cycling.

High-Bandwidth Texture Generation on a TPaD
The focus of this work is to characterize the TPaD’s ability to generate textures on a human fingertip.  A TPaD works to reduce surface friction on glass using ultrasonic vibration normal to the surface.  To create high-amplitude vibrations in the glass, piezo crystals are glued to the surface and excite the glass at a resonant frequency.  The input signal to the piezos is a high-frequency carrier modulated in amplitude by a texture signal.  After the glass is excited, the texture signal has passed through a roughly second order resonant system which results in distortion.  My work on this project includes building a high-bandwidth force measuring device and characterizing the texture signal from the electrical input to the force output.

Electrostatic Force on Human Fingertips
This project pertains to the development of a new tactile display on glass using the principle of electrostatic attraction of fingertip skin to a charged surface.  The focus of this work is to fully understand the electrostatic attraction of a finger to a charged surface and its effect on friction properties.  I am developing a model for the electrostatic attraction in terms of physical properties and applied electric fields.  In addition, I am using a customized friction measuring device, or tribometer, to measure the fingertip friction on a tactile display.  Using friction measurements, I determine the effect of electrostatic attraction force, and compare these data to my model.  This work will ultimately lead to optimization in design of future tactile displays using electrostatic attraction.

Energy Efficient Piezo Amplifier
The focus of this work is on creating a simple and efficient way of driving piezoelectric actuators in TPaDs. The TPaD (Tactile Pattern Device) uses ultrasonic vibration of glass surfaces to create a "squeeze-film" of air beneath a fingertip. This squeeze-film effectively reduces surface friction, and makes possible a programmable friction surface. Combining programmable friction with knowledge of fingertip position leads to touch screens which can render textures and other tactile sensations. In order to vibrate glass at high frequency, piezoelectric actuators are glued to the surface of the glass and supplied with a high frequency AC voltage. Higher voltage signals correspond to higher amplitude motion, but higher voltage signals require more power. I developed an amplifier which uses the energy storage capabilities of an LC oscillator to generate the high frequency, high voltage signal to drive the piezo crystals.

Northwestern University
Doctor of Philosophy in Mechanical Engineering, Dec 2015
Thesis: Design Considerations and Digital Tools for Implementing Variable Friction Tactile Displays

Northwestern University
Master of Science in Mechanical Engineering, Dec 2012
Thesis: Electrostatic Force on a Human Fingertip

Rice University
Bachelor of Science in Mechanical Engineering, May 2010
Concentration in System Dynamics and Control

Teaching Assistant - Electronics Design, ME 233 Fall 2012, 2013, 2014, Northwestern University

Teaching Assistant - Dynamic Systems, ME 343 Fall 2008, Rice University

nScope
The nScope project aims to provide a low-cost portable oscilloscope with power supply, function generator, and digital I/O for students to use in the classroom.  The nScope hardware is a small PCB which plugs into a breadboard for use in building basic circuits.  The PCB is attached to a laptop via USB, over which all power is drawn and communication is maintained.  A graphical display on the computer provides control over the boards outputs as well as a plotting area for viewing the scope inputs.

USB Communication Board
The goal of this project is to create a small USB communication chip for student projects. Students at Northwestern frequently use PIC microcontrollers in class, for master's projects, and for design competitions. Communicating between a PC and a PIC though, is not a trivial task for undergraduates.  The USB communication board automatically translates 4 types of common microcontroller communication into standard driverless HID communication for use on any PC.  This releases the burden of worrying about USB overhead from students, and allows them to focus more on their project. More info on this project can be found on the Northewestern Mechatronics Wiki.