Multidisciplinary Senior Design Wireless Assistive Control System PROJECT 08027

OVERVIEW OF TOPIC CUSTOMER NEEDS FRONT END FILTER DIGITAL SIGNAL PROCESSOR WIRELESS COMMUNICATION SYSTEM PROOF OF CONCEPT (RC VEHICLE) Agenda

Brief Overview

ADVERTISE THE ELECTRICAL ENGINEERING Promote focus within engineering disciplines Biomedical sciences program Signal Processing Control Systems Proof of concept for later projects PROOF OF CONCEPT FOR LATER PROJECTS Why?

ROBUST RELIABLE SAFE No chance of shock Completely non-invasive SIMPLE TO USE WELL DOCUMENTED Basic Needs and Requirements

Documentation Needs

System Level Diagram

The front end consists of the electrodes that are held in place on the person by a “glove” collecting signals produced by muscle contractions. These electrodes are connected to an amplifier. The amplifier sends the data to the filter and eventually wirelessly to our RC vehicle. Front End

“GLOVE” TO BE PUT ON THE PERSON ELECTRODE AND CABLE PURCHASE AMPLIFIER REAL TIME DATA TRANSFER Design Decisions

Design Decisions: “Glove” Design Customer Needs  Needed a glove type piece of apparel that would securely hold EMG electrodes in place while the user moved their arm.  Glove had to be aesthetically appealing, to have a “coolness” factor since it would be used by a department to recruit prospective students.  Glove needed to be strong, durable, and be able to survive extended periods of storage.  Glove also needed to fit a variety of body types and sizes. Aimed to fit 95 th percentile.

Design Decisions: Development of Concepts for “Glove” Arm muscles overlap.  Difficult to accurately place electrodes  Generates “cross-talk” between electrodes Moved to a dual arm design with thumb and forearm electrode locations.  Simpler, more accurate electrode placement  Eliminates “cross-talk”  More intuitive control logic for an operator

Design Decisions: “Glove” Concepts Full Length glove – elastic material (concept A)  Require S, M, L sizes  Glue EMG wires into place inside glove Full Length glove – denim material (concept B)  Adjustable, like a batting glove  Stitch wire into fabric Arm Bands w/ thumb hoop (concept C)  Nylon webbing bands  Run wires underneath bands  Velcro, clips, or slides for adjustability Wrap sleeve w/ thumb hoop (concept D)  Flap of fabric that is wrapped around the arm  Stitch wires into fabric  Velcro to keep sleeve in place

Design Decisions: “Glove” Selection Used the Pugh concept selection process outlined in class. First matrix narrows the field and can provide ideas for improvement of particular concepts.

Design Decisions: “Glove” Selection Second matrix provides concept scoring for increased resolution is need to differentiate between competing concepts Weights are applied to the selection criteria based on the customer needs and priorities.

Design Decisions: “Glove” Materials Material Research: Decided early on to make the arm strap design out of Nylon Webbing for several reasons  Strong  Flexible  Durable  Easy to work with manufacturing wise  Feels relatively comfortable to human skin Found several websites that sold the material in bulk and “cut to length” quantities. Also discovered Nylon Web Tubing.

Design Decisions: Bill of Materials (BOM) for Final Design

Design Decisions: Electrode and Cable Purchase Customer Needs  Electrodes and cables  need to be safe and sanitary.  need to be comfortable  Electrodes  need to stay in place and be applied easily.  need to be conductive enough to acquire an accurate signal.  need to be affordable.

Design Decisions: Electrode Selection Active or Passive  Active: more expensive and larger  Passive: less expensive and flatter Disposable or Reusable  Disposable preferred because reusable may be unsanitary  Also reusable all require an additional adhesive and conducting gel (Comparison Chart: on next slide)

Need: Safety Need: Sanitary Need: Affordable

Design Decisions: Electrodes DDN-20 and DDN-30  Requires additional purchase of wires  + Easy because they are attached with snaps  - But will cost more 1024 and 1025  comes with wires  - $55 for 40  requires alligator clips  + $20 for 100 PT30  - Requires alligator clips  + Most conductive: thick adhesive gel  + Least expensive: $25 for 200

Design Decisions: Electrodes Samples requested Final Decision:  Testing  Hands on PT30 DDN-20

Design Decisions: Real Time Data Acquisition Amplifiers  Grass Technologies Model QP511  BIOPAC Systems Inc. Model MP30A  BOTH tested safe via Fluke Biomedical 180  Connected to data acquisition device then to computer via USB NI-DAQmx will work with DAQ from National Instruments with MATLAB  Free download adds library of commands for data acquisition  Can be used to configure hardware.  Includes example data acquisition programs

The Filter The filter is used to clean up the EMG data so that it can be processed more easily. The data is obtained from the data acquisition device and then processed in matlab. After the data is processed, it will be fed into the control system.

High Level Overview of the Filtering

FILTER TYPE WINDOW TYPE Design Decisions

Design Decisions: Filter Selection  Analog  - Implementing  + Price  + Efficiency  - Versatility  Digital  + Implementing  + Price  + Efficiency  + Versatility

Design Decisions: Window Type  Hamming  + Stopband attenuation  + Raised cosine  Bartlett  - Stopband attenuation  Uniform  - Stopband attenuation

The Unprocessed EMG Data

The EMG data in the Frequency Domain

The Data After Filtering

Pre/Post Filtering Comparison

DSP PROCESSOR CHOICE CONTROL SYSTEM MODEL Control System Design Choices

DSP Processor & Development Board  BF531 – Development kit  + User friendly IDE  - GPIOs  + Cost of purchase (~$250)  BF537 – Development kit  + Cost (~$250)  + User friendly IDE  + GPIOs  TMS320C Development kit  - Cost (~$600)  + User friendly IDE  + GPIOs

Control System Model Physical Model of the situation

Input Model

I/O Relationship

Model Attributes The model logic itself is inspired from Fuzzy Logic, however due to the lack of overlapping membership function full implementation of Fuzzy Logic is unnecessary.

Proof of Concept: RC Vehicle The RC Vehicle is a system acting in response to the sampled EMG data. It will act as a proof of concept for the other subsystems of the project. The vehicle will be controlled through a wireless communications link interfaced with the controller.

HARDWARE PLATFORM MICROPROCESSOR SELECTION WIRELESS COMMUNICATIONS Design Decisions

Design Decisions: RC Vehicle Selection Options:  4WD1 – Robotics kit from lynxmotion.com  + Immediately available  + Simple to develop  - Poor Extendibility  - High cost of purchase (~$400)  Home-made RC vehicle  + Cost (~$120)  + Highly extensible  - Increased development time

Design Decisions: Microprocessor Selection Options:  EZ 430  + Low cost  + Faculty Familiarity  - Only 1 PWM  ATtiny2313  + Low cost  + 4 PWMs  PIC 16F888  + Low cost  + 2 PWMs

Design Decisions: Wireless Comm. Link Options:  Wifi x  - High cost ($200 each)  - ~30 meter range  - Complicated to interface with  Bluetooth Class 1  meter range  - Cost ~$60 each  Zigbee (2006)  + Low cost  - 30 meter range  Sparkfun RF Link  + Low cost ~$17/pair  + Simple interface  meter range  - Low speed 4800 bps

NEEDS Provide direction and magnitude for Forward/Reverse Left/Right Discretely updated at defined interval Specifications: Wireless Comm. Protocol

Restrictions  ATtiny2313  8bit registers  RF Link  Maximum ideal transmission speed: 4800bps

Specifications: Wireless Comm. Protocol Right/Left Direction Control  16 Positions Forward/Reverse Direction Control  16 Positions

In Summary Overview of Topic Customer Needs Front End Filter Digital Signal Processor Wireless Communication System Proof of Concept (RC Vehicle)

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