Using A Raspberry Pi to Control Scientific Instruments over LAN and Instrument Control Consolidation Using the Scientific Programming

Environment Matlab Matthew Herndon

Lloyd Bumm Research Group03/29/2014

Presentation Overview:

•Part One

Control USB interfaced scientific instruments over a Local Area Network (LAN) using a Raspberry Pi

•Part Two

Create a single, feature-rich interface capable of controlling many scientific instruments using simple Matlab code.

•Acknowledgments

Part OneUSB over LAN with Raspberry Pi

Controlling USB devices over LAN with a Raspberry Pi•It was decided that this communication would be done using a technique called USB over IP

•This works by encapsulating USB packets within TCP/IP packets and sending them over a network to be interpreted by a remote client

•The Raspberry Pi had a program called VirtualHere USB IP readily available, so I made use of that

USB over LAN vs. direct USB: Why?• It’s much more convenient• Virtually no cable restrictions

USBDevice

HostComp.

ServerComp.

USBDevice

Network HostComp.

USB: Limited to <16 ft without repeaters

Virtually no limit on the physical distance

between the two devices

USB over IP: The general idea

TCP/IP Packets

TCP/IP Request

Received Data

TCP/IP Request

Received Data

Write Received Data

Read Incoming Data

Convert Incom

ing Data to

TCP/IP, Send to C

lient

Convert TC

P/IP packets from

client back to USB

packets

Wrap data from

virtual USB

as TC

P/IP, send to server.

Convert TC

P/IP packets from

server back to USB

packets

Write Received Data

Read Incoming Data

Effective Bridge

Remote Physical

USBDevice

USB IP Server

Software

USB IP Client

Software

Rasbian OS

VirtualUSB

Device

Windows OS

Client Network

Hardware

Pi Network

Hardware

Raspberry Pi

Windows PC

TCP/IP Packets

The Raspberry Pi SetupFilter WheelShutterRaspberry Pi

Part TwoSensor Control Consolidation Using

Matlab

Goals•Create an interface that allows one to control a group of instruments with ease through one unified interface

•Make this interface handle the initialization of all of the instruments, a process which can often be complicated and easy to forget

•Make this interface easy to use, modular, and intuitive

Seen Below: The initialization code for the Shutter.

Problems to Overcome:•How to organize the program so as to insure modularity without compromising an intuitive user experience

•How to effectively implement it within Matlab

Organization•This problem was solved using the design concepts of Object Oriented Programming (OOP), as seen in the Unified Modeling Language (UML) diagram to the right.

Class Name

Class VariablesMethods

Implementation

•UnifiedHandler should only be instantiated once, butMatlab’s handling of OOP makes this difficult

•Using a Singleton class solved this problem•Only allows one instance to be created•Can still be referenced multiple times.

•Easy to use, easy to read

•Example code:

The Final Product

uh=UnifiedHandler(1);

uh.Shutter.open();

uh.FilterWheel.moveToPositionN(3);

% UnifiedHandler instantiation statement% Variable that holds the instantiated UnifiedHandler object% Function call that references one of UH’s internal objects% Function call to a function within an internal instrument

Future efforts

•Improve basic functionality of the UnifiedHandler class. •Improve how certain functions in the Shutter class work, making sure to utilize built in features of the Shutter controller to insure maximum performance

•Better error handling, more predictable performance

•Make it easier to use client computers by compiling a list of required software for Shutter, Filter Wheel, etc.

My fellow group members: Michael Reynolds, Nick Kantack, Mitchell Yothers, Jacob Higginbotham, for their help and support

More Specifically:•Dr. Lloyd Bumm, for his assistance in all aspects of my projects•Nick Kantack, for his work on communicating with the Shutter over USB

•Eric Holbrook, for his work on communicating with the Filter Wheel over USB

•Mitchel Yothers, for helping me learn Matlab•VirtualHere Pty. Ltd, for their USBIP software package•UROP, for their generous grant•The HERE program, for providing me with this research opportunity

Acknowledgements

Questions?