Daniel S. Drew

UC Berkeley PhD candidate
Electrical Engineering

email me: ddrew73 at berkeley.edu

I make flying microrobots using ion thrusters ("ionocraft") and develop new tools to help people develop and debug embedded systems projects.

About Me
I'm a huge sci-fi (and everything else) reader. Here's a link to my goodreads page. I've done a fair amount of both solo and group world traveling and look forward to a lifetime of more. Here's a link to my extremely sporadically updated Flickr page. Send me an email with your wild dreams of the future; I want to hear it all.

I received my B.S. in Materials Science and Engineering from Virginia Tech in 2013. My past research includes electromagnetic railguns and polymer-metal nanoparticle compounds for energy efficient mechanical switching. I began the MS/PhD program at UC Berkeley in Fall 2013 with a MEMS concentration. I was also awarded an NSF Graduate Research Fellowship in 2013.

Now I work with Professor Kris Pister on ionocraft, flying microrobots powered by atmospheric ion engines. I also do some work with Professor Bjoern Hartmann on developing novel systems for debugging.

Journal/Conference Papers
Bifröst: Visualizing and Checking Behavior of Embedded Systems across Hardware and Software
Will McGrath, Daniel Drew, Jeremy Warner, Majeed Kazemitabaar, Mitchell Karchemsky, David Mellis, Bjoern Hartmann, UIST 2017
This paper presents a new development environment designed to illuminate the boundary between embedded code and circuits. Bifröst automatically instruments and captures the progress of the user's code, variable values, and the electrical and bus activity occurring at the interface between the processor and the circuit it operates in. This data is displayed in a linked visualization that allows navigation through time and program execution, enabling comparisons between variables in code and signals in circuits. Automatic checks can detect low-level hardware configuration and protocol issues, while user-authored checks can test particular application semantics. In an exploratory study with ten participants, we investigated how Bifröst influences debugging workflows.
Link to the paper
Geometric Optimization of Microfabricated Silicon Electrodes for Corona Discharge Based Electrohydrodynamic Thrusters
Daniel S Drew, Kristofer S J Pister, Micromachines, Microplasmas issue
In this work, an array of hybrid wire-needle and grid electrode geometries were fabricated and characterized to attempt to minimize both corona discharge onset voltage and thrust loss factor. Statistical analysis of this dataset was performed to screen for factors with significant effects. An optimized emitter electrode decreased onset voltage by 22%. Loss factor was found to vary significantly (as much as 30%) based on collector grid geometric parameters without affecting discharge characteristics. The results from this study can be used to drive further optimization of thrusters, with the final goal of providing a path towards autonomous flying microrobots powered by atmospheric ion engines.}
Link to the paper

First Takeoff of a Flying Microrobot With No Moving Parts
Daniel S Drew, Kristofer S J Pister, MARSS 2017, Best Paper nominee
In this work, we demonstrate an insect-scale robot capable of vertical takeoff using electrohydrodynamic thrust, a mechanism with no natural analogue. The 10mg, 1.8cm by 1.8cm "ionocraft" operates at about 2400 volts and has a thrust to weight ratio of approximately 10. Feasibility of using individually addressable thrusters in a quadcoptor-esque manner for attitude control is demonstrated qualitatively. A combination of design choices in the microfabricated silicon electrodes and a machine-fabricated external fixture allow for reproducible hand-assembly of the microrobot.
Link to the paper

Future Mesh Networked Pico Air Vehicles
Daniel S Drew, Brian Kilberg, Kristofer S J Pister, ICUAS 2017
Taken together, recent advances in microelectromechanical systems, wireless mesh networks, digital circuits, and battery technology have made the notion of autonomous pico air vehicles viable. In this work we describe the core technologies enabling these future vehicles as well propose two possible future platforms. We draw on recent research on high thrust density atmospheric ion thrusters, microfabricated silicon control surfaces, and extremely low mass and power mesh networking nodes. Using the same open-source network implementation as we have already demonstrated in larger UAVs, these flying microrobots will open up a new application space where unobtrusiveness and high data granularity are vital.
Link to the paper

First Steps of a Millimeter-scale Walking Silicon Robot
Daniel S Contreras, Daniel S Drew, Kristofer S J Pister, TRANSDUCERS 2017
We present the first evidence of locomotion from a walking silicon robot based on a two degree-of-freedom robot leg with the largest force and displacement of any electrostatically-driven SOI leg to date. The peak vertical force is five times the weight of the robot. Using a new approach, the robot stands with the chip vertically and has demonstrated its ability to lift itself and move forward while actuating the leg on the ground under tethered power and control. This is the simplest process (2 mask SOI) for making an electrostatic SOI robot that has been demonstrated.
Link to the paper

First Thrust from a Microfabricated Atmospheric Ion Engine
Daniel S Drew, Daniel Contreras, Kristofer S J Pister, MEMS 2017
The bulk of current research in the realm of pico air vehicles has focused on biologically inspired propulsion mechanisms. In this work we investigate the use of electrohydrodynamic thrust produced by a microfabricated corona discharge device as a mechanism to create flying microrobots with no moving parts. Electrodes of various geometries are fabricated from a silicon-on-insulator wafer with a two mask process. Electrical characterization is performed to analyze the effect of inter-electrode gap and emitter electrode width on corona discharge and compare findings to simulation. Outlet air velocity and thrust are directly measured to analyze the effects of collector electrode geometry on performance. A roughly 100 cubic millimeter, 2.5mg thruster is assembled with a thrust to weight ratio exceeding 20.
Link to the paper

The Toastboard: Ubiquitous Instrumentation and Automated Checking of Breadboarded Circuits
Daniel S Drew, Julie Newcomb, William McGrath, Filip Maksimovic, David Mellis, Bjoern Hartmann, UIST 2016
The recent proliferation of easy to use electronic components and toolkits has introduced a large number of novices to designing and building electronic projects. Nevertheless, debugging circuits remains a difficult and time-consuming task. This paper presents a novel debugging tool for electronic design projects, the Toastboard, that aims to reduce debugging time by improving upon the standard paradigm of point-wise circuit measurements. Ubiquitous instrumentation allows for immediate visualization of an entire breadboard's state, meaning users can diagnose problems based on a wealth of data instead of having to form a single hypothesis and plan before taking a measurement. Basic connectivity information is displayed visually on the circuit itself and quantitative data is displayed on the accompanying web interface. Software-based testing functions further lower the expertise threshold for efficient debugging by diagnosing classes of circuit errors automatically. In an informal study, participants found the detailed, pervasive, and context-rich data from our tool helpful and potentially time-saving.
Link to the paper
Workshop Papers

Investigation of Atmospheric Ion Thrusters Using Rapid Prototyping Techniques
Daniel S Drew, Joseph Greenspun, Kristofer S. J. Pister, Robotics Science and Systems (RSS):Robot Makers 2014
Electrohydrodynamic (EHD) thrusters, which use ionized air under the influence of an electric field to produce a force, have been investigated for the purposes of flying vehicles for decade. This work focuses on leveraging the precision and speed of rapid prototyping techniques such as 3D printing and laser engraving in order to rigorously investigate this phenomenon at scales relevant to microrobot research.
Link to the paper

Research Dreams
  • "Gnat" robotics
  • The other day I wanted to move a big houseplant of mine to a spot where it would get more midday sun. I'm not home enough during the early afternoon to really remember where the sun shines brightest. What's a simple and cheap way to figure this out? My engineer brain says to prototype some sort of photodiode array with Arduino and log the results... but what if I could just take a handful of tiny robots out of my pocket and throw them into the room? This isn't a problem that requires much intelligence, mobility, or lifetime; all they have to do is spread out in one room and record light every 30 minutes. I won't even pick them up when they're done, I'll let them "self-destruct."
    Flynn, Anita M. "Gnat robots (and how they will change robotics)." (1987).

  • How do humans interact with swarms?
  • I hate when people fly quadcoptors near my head, especially the little ones that make the extremely high pitched rotor noises (must be the primal fear of eye gouging). Just imagine when autonomous swarm technology matures and we have thousands of them flying around at once. Right now the research is heavily focused on industrial and commercial applications, but even then someone is going to have to interact with these swarms. How do you interact with Honda's ASIMO? You can shake its hand. How do you interact with a Boston Dynamics' Spot? Maybe pat it on the head. Interacting with a swarm of buzzing insects is out of the realm of human experience.

    I want to use virtual reality as a tool to simulate human interaction with autonomous microrobot swarms. How can a swarm express its intentions? How should it use situational context to modify its own behavior?

  • Big data from lots of small things
  • One estimate is that there are 10 quintrillion insects on earth at any one time- that's 10^19. The trillion-sensor movement as currently conceptualized relies on human installation and maintenance, with industrial pushes largely towards longer device lifetime so humans have to go service motes less often. Let's provide each of these sensor motes with its own mobility platform; we already know from nature that there is an insect to suit every environment and that they have no trouble spreading. Moving beyond the almost cliche application example of "search and rescue," how can we use these swarms to change the world?
    The future of flying robots - Vijay Kumar from UPenn