automatic weightlifting spotter mid semester presentation senior design i february 27, 2014
TRANSCRIPT
Automatic Weightlifting Spotter
Mid Semester PresentationSenior Design I
February 27, 2014
Team Members
Chris ChildersElectrical
Engineering
Nathan CarrollElectrical
Engineering
Garrett DoorenbosElectrical
EngineeringTeam Leader
Drew BosargeElectrical
Engineering
Faculty Advisor
Dr. Robert Reese
Professor
ECE Department
Outline• Problem
• Solution
• System Overview
• Constraints
❖ Technical
❖ Practical
● Approach
● Progress (Timeline)
● Questions/Comments
Problem
• When lifting free-weights, a spotter must be present to ensure the safety of the lifter.
• When a spotter is unavailable, weightlifters are likely to lift without one, exposing themselves to injury and possibly death.
• From the years 1999-2003:o 1-4 deaths annually involved asphyxiation from neck compressiono As many as 3,820 injuries per year may be related to bench press
failures[1]
Solution
A microcontroller-based system that will use sensors and a motor to allow users to lift
weights safely without a spotter:
The Automatic Weightlifting Spotter
System Overview
• Sensors determine position, speed, and direction of barbell
• Microcontroller reads sensors and sends directions to motor
• Motor lifts the barbell as instructed by the microcontroller
Technical ConstraintsName Description
Detection of Bar The device must detect the position, speed, and direction of the bar.
Weight Limits The Automatic Weightlifting Spotter must be able to handle weights ranging from 45 pounds to 405 pounds.
Reaction Time The product must have a reaction time that is fast enough to protect the user from falling weight.
Notifications The Automatic Weightlifting Spotter must implement a user interface to indicate the status of the machine to the user.
Power Requirements The device must run on 120 VAC power.
Practical Constraints
Type Description
Health and Safety
Fail-safes must be implemented to prevent possible injuries to the user.
Usability The product should not be used by beginners and must come with an owner’s manual.
Approach
MotorPros Cons
DC Winch ● Simple process to control speed.
● Could use car battery for power.
● Would have to heatsink 30A.
● Car battery would have to be charged frequently.
AC Winch ● Already variable speed.
● Plug into wall outlet for power.
● More complicated speed control.
[3]
[2]
Microcontroller
[4]
[5]
IO pins Price
Arduino Mega
54 $58.95
dsPIC33 21 ~$2
User Display
Pros Cons
Seven Segment Display ● Easy to use ● Not able to display much info
LCD Display ● A lot of info can be displayed
● Many IO pins are required
Laptop Interface ● Easiest to create● No extra hardware
required
● Not practical for weightlifting environments
Weight Sensor
Pros Cons
Tension sensor Direct measurement of weight
Has to be inline with the tension cable, hard to find
Pressure sensor Can lay in rack while the weight is stationary
Requires extra hardware and software calculations to work
Supporting Frame
[6]
Cost
Build frame from scratch using wood ~$8 for 4”x4”x8’ board
Build frame from scratch using Steel ~$120 for 4”x4”x8’ bar
Purchase Power Cage to act as frame ~$350
Barbell Attachment
• Hole in bar with cable hookup
to machine
• Tow straps attached to each end of bar
• Use eye clamps on each end of the bar
[9]
[8]
[7]
Wheel EncodersPros Cons
LED encoder Easier to implement and debug
Light can cause interference
Hall-Effect encoder Light not an issue Harder to debug
[10] [11]
Progress: TimelineJanuary February March April
Research, Documentation, and Analysis
Order parts
Build frame
Implement user display
Design Software
Implement Sensors
Testing
Finalize & Present Design
References[1] V. Patteson Lombardi, “Petition Requesting Labeling of Weightlifting Bench-Press Benches to Reduce or Prevent Deaths Due to Asphyxia/Anoxia,” unpublished.
[2] http://www.globalindustrial.com/p/material-handling/dock-truck/winches/warn-1700-dc-powered-
1700-pound-capacity-12v-utility-w. Feb. 26, 2014.
[3] http://www.globalindustrial.com/p/material-handling/dock-truck/winches/warn-works-pullzall-
handheld-110v-ac-electric-portable-pulling-li-ing-tool
[4]http://arduino.cc/en/uploads/Main/ArduinoMega.jpg. Feb. 26, 2014.
[5]http://www.electropages.com/2013/02/farnell-element14-ideal-prototyping-popular-16-bit-dsc-family-expanded-dip-packages/. Feb. 26, 2014.
[6]http://dldiscountfit.com/racks/power. Feb. 26 2014.
[7]http://totalgymcare.com.au/sales/images/uploads/Snap_Hook_Final.JPG. Feb. 26, 2014.
[8]http://simage1.sportsmansguide.com/adimgs/l/1/140756_ts.jpg. Feb. 26, 2014.
[9]http://www.bhphotovideo.com/bnh/controller/home?O=&sku=690061&Q=&is=REG&A=details. Feb. 26, 2014.
[10] https://www.sparkfun.com/products/241. Feb. 27, 2014.
[11] https://www.sparkfun.com/products/9312. Feb. 27, 2014.
Automatic Weightlifting Spotter
Mid Semester PresentationSenior Design I
February 27, 2014