Automatic Weightlifting Spotter Mid Semester Presentation Senior Design I February 27, 2014

Team Members Chris Childers Electrical Engineering Nathan Carroll Electrical Engineering Garrett Doorenbos Electrical Engineering Team Leader Drew Bosarge Electrical 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 : o 1-4 deaths annually involved asphyxiation from neck compression o 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 Constraints NameDescription 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 TypeDescription Health and Safety Fail-safes must be implemented to prevent possible injuries to the user. UsabilityThe product should not be used by beginners and must come with an owner’s manual.

Approach

Motor ProsCons 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 pinsPrice Arduino Mega 54$58.95 dsPIC3321~$2

User Display ProsCons 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 ProsCons Tension sensorDirect measurement of weight Has to be inline with the tension cable, hard to find Pressure sensorCan 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 Encoders ProsCons LED encoderEasier to implement and debug Light can cause interference Hall-Effect encoderLight not an issueHarder to debug [10] [11]

Progress: Timeline JanuaryFebruaryMarchApril 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] pound-capacity-12v-utility-w. Feb. 26, [3] handheld-110v-ac-electric-portable-pulling-li-ing-tool [4] Feb. 26, [5] packages/. Feb. 26, [6] Feb [7] Feb. 26, [8] Feb. 26, [9] Feb. 26, [10] Feb. 27, [11] Feb. 27, 2014.

Automatic Weightlifting Spotter Mid Semester Presentation Senior Design I February 27, 2014