The WeedRake By Nick Bigelow, Matt Merrit, Tyrel Ellis and Jason Pemberton

Background Weed removal is a labor intensive, time consuming part of owning a garden Some gardeners use herbicides to shorten and simplify the process Herbicides are harmful to the environment The stalks are 12” apart with a roughly 4” diameter of roots that can not be damaged Corn stalks are at least 5” tall

Problem Statement We need to find a way to use MARV to remove weeds automatically without the help of human hands

Solution We are going to use a rake assembly to remove the weeds We are using ultrasonic sensors for plant detection and navigation of the WeedRake

System Overview Diagram

Flow Chart

PING))) Sensor Specs Range: 2cm to 3 m Supply Voltage: 5V Supply Current: 30mA Input Trigger: 5us typ. Echo pulse: 115us min to 18.5ms max

Sensor Diagram HC12

Rake Mechanism

Lifting Mechanism

State Diagram

Torque Calculations It will take about 30 inch pounds to push the rake assembly out

Motor Specifications We are using the DENSO DC gear motors for moving the rake mechanism These motors operate at 12 volts and have a no load current of 1.5A The motors turn at 162 RPMs

Motor Controller

Calculating Motor Travel 13 threads per in 6 inches horizontal travel 162 RPM 1 rev = 1 thread 13 TPI x 6 Inches = 78 threads 78 threads / 162RPM =.48 minutes.48 minutes = 28 seconds

MARV Speed Max Speed is 3.9 mph Uses 2 DENSO DC gear motors (12V,1.5 A, 162 RPM) 8 inch Diameter wheels We will limit MARV to a speed of 6 inches per second 6 inches per second is 8.7% of MARV’s top speed

Personal Assignments Nick and Jason on the extension mechanism Tyrel and Matt on the lift mechanism Jason and Nick on programming MARV and the motor controller board Tyrel and Matt built the rake mechanism

Budget CostCost to Us Two Motors$40.00Borrowed 3 ft threaded rod$5.00 Relays$6.86Borrowed Rake$8.00Donated 1" square stock$5.86Donated 1.5" square stock$9.60Donated Total$75.32$5.00

Schedule