Human Electric Trike Thesis

Design of an electrically assisted human powered trike

Archive for September, 2006

Fabrication Status

Posted by Bob Dold on Saturday, September 30, 2006 3:36 PM

Fabrication of components is progressing ahead of schedule, the spreadsheet below shows the status of the parts that have been completed and those that are left to build:

On Friday I went into the shop and cut most of the tubing to length for the frame rails and rear swing arm. I also did the the bonding of the lower a-arm assemblies using the Loctite 680 as the adhesive. Bond prep consisted of  cleaning with Scotchbrite and then wiping with Acetone and then applying the green adhesive. The 680 took about 15 minutes to set and seemed to completely cure in about 24 hours. The pictures below show the lower a-arm and the sides of the swingarms bonded together:

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Water jet part quote

Posted by Bob Dold on Saturday, September 30, 2006 3:02 PM

Found an online waterjet cutting service that provides instant quotes for cutting parts from a DXF file: www.bigbluesaw.com. I arranged all my 1/4″ aluminum plate parts I need made into an assembly file and nested them together to reduce the material needed. I then uploaded it to Big Blue Saw and they provided the following picture of the cut parts:

Their online software automatically identified the 22 parts and provided the following quote:

Delivery is 2-3 weeks.

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Garmin Edge 205 GPS

Posted by Bob Dold on Friday, September 29, 2006 2:54 PM

While looking for components to set up a data acquistion system I came across this $200 bike GPS with logging software. I think this may do the job in logging speed and grade better than trying to fabricate my own using and inclinometer and data acquisition board. To track current I may still need a current logging system that I can sync to the Edge results. Cheapest inclinometer I could find was $150 + $109 USB data board which still requires software, a way of measuring speed, and carrying around a laptop on the trike:

Sample plot from GPS software:

Take your ride to the next level with the Garmin Edge 205 – Garmin’s GPS-enabled personal trainer and cycle computer. Perfect for touring and the trails, the lightweight Edge is the ultimate fitness partner. With the easy-to-use Edge 205 on your bike, you always know where you’re going and how far you’ve gone. For advanced cyclists, the Edge 305 is available with either a heart rate monitor or a wireless speed/pedaling cadence sensor to help you achieve your personal best.

The Edge 205 measures speed, distance, time, calories burned, altitude, climb and descent, plus much more. 205 features include:

  • Easy-to-install – no calibration required. Just snap it in the included bike mount and go
  • High-sensitivity GPS receiver – knows your position even in tree cover and canyons, making it extremely reliable for navigation
  • Customizable cycle computer – shows up to eight different data fields for continuous feedback
  • Virtual Partner – lets you “race” a virtual competitor, making training fun
  • Courses – lets you “race” against a recorded course to try to match previously set speeds at every point along the way
  • Auto Pause – pauses the training timer when you slow down below a specified speed and resumes when you speed up again so you can focus on your ride
  • Training Center software – gives you the ability to create workouts, manage and download courses, and create a detailed post-ride analysis that charts your performance

With its waterproof, sleek design, the Edge is the perfect companion on any bike, and attaches to either the stem or handlebars. Its rugged case frames an easy-to-read, large, backlit display that can show up to eight different data fields along with altitude and a map view.

Included Training Center software gives you the ability to overlay your ride data onto a course map. It offers interactive analysis tools that measure your speed, distance, climb, and descent against varying terrain, elevation and more. Create and schedule custom workouts or use workout templates and download to the Edge.

Edge 205 Features:

  • GPS: High-sensitivity SiRFstarIII receiver
  • Antenna: Built-in patch GPS antenna
  • Weight: 88 g, 3.1 oz.
  • Display: 1.17″W x 1.44″H, 128 x 160 pixels, 4-level grayscale LCD with backlighting
  • Unit dimensions: 1.75″W x 3.7″H x .9″D (44 x 94 x 23 mm)
  • Waterproof: IEC 60529 IPX7 standards (submersible in one meter of water for up to 30 mins.)
  • Battery: Up to 12 hours (typical use); rechargeable internal lithium ion
  • Track log: 13,000 track points

Package Includes:

  • Edge 205
  • Bike mount
  • Training Center CD
  • A/C charger
  • USB PC interface cable
  • Quick reference guide
  • Owner’s manual

Specifications

Features

  • Training data: Speed, distance, cadence (305 only), heart rate (305 only), lap by position, elevation, average and max speed, calories burned, climb and descent
  • History: Automatically records up to 1000 laps. Download to your PC using included Training Center software.
  • AutoPause: Automatically pauses the training timer when you slow down below a specified speed; timer resumes when you speed up again
  • AutoLap: Automatically triggers a lap every time you pass a specified location or travel a preset distance
  • Courses: Race against a recorded course and previous raced speeds at every point along the way. Combine Courses and Virtual Partner features and race an opponent that varies speed while climbing hills and navigating turns.
  • Virtual Partner: Race against a virtual competitor. Depicts a digital cyclist (desired speed) in relation to your real-time speed and shows how far ahead or behind you are.
  • Alerts: Speed, time, distance, heart rate (305 only), cadence (305 only)
  • Calories: Calculates calories burned based on user profile, performance data and altitude changes
  • Training Center: PC-based software (included) overlays ride data on a map and graphs speed, pace, heart rate, cadence and elevation. Create and schedule custom workouts or use workout templates and download to the Edge.

Navigation features

  • Receiver: SiRFStarIII high sensitivity receiver
  • Mark location: Mark and save up to 100 locations
  • Find location: Look up and navigate to stored locations
  • Back to start: Navigate back to starting location
  • Track log: 13,000 track points

Physical

  • Size: 1.75″W x 3.7″H x .9″D (44 x 94 x 23 mm)
  • Display: 1.17″W x 1.44″H (29.65 x 36.69 mm), 128 x 160 pixels, 4-level grayscale LCD with backlighting
  • Weight: 88 g
  • Waterproof: Waterproof to IEC 60529 IPX7 standards. All components are submersible in 1m of water for 30 minutes
  • Battery: 800 mAh rechargeable lithium-ion battery; 12 hours typical use
  • Antenna: Internal patch
  • Mount: 2-piece mount with zip ties; mounts on stem or handlebars
  • PC Interface: USB

Sensors

  • Heart rate: Robust wireless transmission; sends heart rate data to Edge via chest strap
  • Speed/cadence: Self-calibrating wireless sensor mounts to bike’s rear chain stay. Wheel magnet mounts to rear wheel for speed; cadence magnet attaches to crank arm.

Edge series comparison guide

Here’s how the units are different:

  • Edge 205 (this page):
  • Altitude: GPS based
  • Elevation profile: yes
  • Cadence: no
  • Heart rate: no
  • Edge 305HR:
  • Altitude: barometric altimeter
  • Elevation profile: yes
  • Cadence: yes with purchase of speed/cadence kit
  • Heart rate: yes
  • Edge 305CAD:
  • Altitude: barometric altimeter
  • Elevation profile: yes
  • Cadence: yes
  • Heart rate: yes with purchase of heart rate monitor kit

Product Shots:

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Data acquisition system

Posted by Bob Dold on Thursday, September 28, 2006 12:11 PM

In order to evaluate the performance of the completed trike I plan on putting together some instrumantation to measure it’s performance. Variables I would like to log are the following:

 Speed

Time

Grade

Motor Amps

From these I can compare the actual performance to the predicted performance calculations I have made. To recored the data Dr. K.J pointed me to this $109 USB DA board: http://www.measurementcomputing.com/cbicatalog/cbiproduct_new.asp?dept_id=412&pf_id=1535&mscssid=JCM5JCEEDRK38KSPRT8QX1R3D4TK5GC7

pmd-1208lssmall.gif

This will plug into a laptop and allow recording of up to 8 analog inputs – currently I will need only three:

speed – optical sensor

grade – inclinometer

amps – measure voltage with shunt

The time can be tracked within the DA module, it is possible I could use additional inputs for TC’s or strain gages.

Here are some links to different inclinometers:

http://www.riekerinc.com/ElectronicInclinometers.htm

http://www.cfxtech.com/

http://www.usdigital.com/products/incremental-inclinometers.shtml

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Cleverchimp: Stokemonkey: Overview

Posted by Bob Dold on Wednesday, September 27, 2006 12:07 PM

Cleverchimp: Stokemonkey: Overview

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Gearing calculations

Posted by Bob Dold on Monday, September 25, 2006 11:50 PM

A spreadsheet was constructed to calculate the optimum gearing for the trike, by using a 14 tooth sprocket on the scooter gearbox and a 34 tooth cog on a mid drive, the motor can be geared down enough to allow the motor to make it up a 10% grade.

The picture below illustrates the chain drive layout:

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Suspension motion analysis

Posted by Bob Dold on Monday, September 25, 2006 10:20 PM

Created a motion model using CosmosMotion software to predict loading on shocks throught the suspension travel. The plot below shows the loading on the front shock vs. the shock travel, the nominal shock position is at .5 inches.

The plot below is the loading on the rear shock from the swingarm:

In both cases the load increases near the end of the travel due to the mechanical advantage of the linkage. The applied wheel load is 1G in the vertical direction.

Link to rear suspention AVI: rear_arm.avi (9Mb)

Link to front suspension AVI: front_susp.avi (8Mb)

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Stealth 1000 performance

Posted by Bob Dold on Sunday, September 24, 2006 10:21 PM

Assembled the Stealth 1000 and took it on a test ride today to get an idea of the performance. After charging the batteries I was able to get a little over 4.1 miles of range on the first charge, this ride included going up several steep hills which cut down on the range. Top speed was about 18 MPH on level ground, one problem that popped up is that the motor controller shut down whenever the scooter went over 20 MPH, to reset it, the power had to be cycled on and off after coming to a stop. Schwinn Stealth 1000 Electric ScooterThis was probably due to the lack of a freewheel on the motor, this won’t be a problem on the trike instalation because there will be a freewheel to allow the trike to coast without backdriving the motor. Another issue was the scooter couldn’t make it up anything steeper than a 5% grade without the controller shutting off after the scooter slowed to about 5 MPH. The motor was not hot, so I assuming this was due to a current limiter in the controller. One work around for this may be to get a controller with an adjustable current limit so a higher shutoff can be set. On the trike the gearing will help reduce the torque required so the current draw shouldn’t be as severe as the scooter which has a fixed gear ratio. Best battery life seemed to be at about 12.5 MPH

Motor information from nameplate:

36 VDC, 78% Efficiency

Rated Speed: 3600 RPM, 32A, 1000W

Model: XYD-18A

Posted in Performance | 3 Comments »

Received Stealth 1000 scooter

Posted by Bob Dold on Thursday, September 21, 2006 10:28 PM

I received the Schwinn Stealth 100 scooter today and assembled it and then took apart the rear wheel drivetrain to measure the motor/gearbox. I was able to remove the wheel ad motor assembly after removing 12 screws and then tapped the wheel off the gearbox shaft. the wheel was keyed to the 12 mm shaft with a 4mm key. After removing the motor guard/mount I weighed the assembly and took of the gearbox cover to inspect the gears. The gearbox uses a 10 tooth pinion, 58 tooth idler gear , and 68 tooth drive gear for an overall reduction of 6.8:1. The gears are packed with grease as shown in the picture below:

Several other Stealth 1000 owners posted  that they replaced the grease with oil to get a quieter geartrain, although I didn’t think it made much noise on my first test drives. The next picture shows the gearbox with the guard/mount removed, this assy weighs about 9 lbs.

After measuring the gearbox I created a SolidWorks model of it and started trying to fit it into the rear frame:

After evaluating various methods for getting the gearbox power to the rear wheel I settled on driving a 5 speed cassette mounted from the swingarm with a 14 tooth freewheel on the gearbox output shaft. With this driving the 38 tooth cog on the freewheel I will be able to gear down the motor enough to drive the 7 speed rear cassette at the same speed as the rider’s cadence.

Posted in Components, Design | 1 Comment »

Updated frame length

Posted by Bob Dold on Tuesday, September 19, 2006 1:15 PM

Pictured below is the frame lengthened by 2.13 inches to allow the three Odyssey 12V batteries to fit. One advantage of these over the Optima’s is that they are much shorter and have side terminals allowing the seat height to be lowered which will reduce the CG and should improve handling.

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