David Young
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    • Computer Science >
      • Computer Vision >
        • 2016 - Homography w/ RANSAC
        • 2016 - Fundamental Matrix & Triangulation
        • 2016 - Laplacian Blob Detector
        • 2016 - Photometric Stereo: Shape From Shading
        • 2015 - Optical Character Recognition w/ OpenCV and Deep Learning
        • 2015 - Feature Detection
        • 2015 - Feature Description
        • 2015 - Feature Matching
        • 2015 - Panoramas (Alignment, Stitching, Blending)
        • 2015 - Facial Detection & Recognition
        • 2015 - Single View Modeling
      • Artificial Intelligence >
        • 2019 - Talk: How Neural Networks See the World
        • 2018 - Generating Text and Poetry
        • 2015 - Optical Character Recognition w/ OpenCV and Deep Learning
        • 2015 - Constraint Satisfaction Problems
        • 2015 - Adversarial Search
        • 2015 - Path Planning (Mazes + Pacman)
        • 2015 - Digit Classification (Bayes)
        • 2015 - Text Document Classification (Bayes)
        • 2015 - Multi-Class Perceptrons
        • 2015 - Markov Decision Processes & Reinforcement Q-Learning
        • 2015 - Simulating Neuronal Learning during Brain-Machine Interface
      • Machine Learning >
        • 2016 - Naive Bayes Classifiers in R
        • 2016 - Stochastic Gradient Descent (SVM in R)
        • 2016 - Comparing Classifiers in R
        • 2016 - Visualize High Dim Data: Blob Analysis + PCA
        • 2016 - Image Segmentation w/ EM
        • 2016 - Regression Kernel Smoothing
        • 2016 - Multinomial Regression on Wide Datasets
      • Robotics >
        • 2017 - 3dof Parallel Motion Simulator
        • 2015 - Designing a Hybrid Controller
        • 2015 - Controlling Pendubot with a Kinect
      • Computer Architecture >
        • 2016 - Architecture Support for Accelerator Rich CMPs
        • 2014 - Weighted Vector Addition with Cuda Framework
        • 2014 - Parallel Reduction with Cuda Framework
        • 2014 - Designing a Pipelined CPU
        • 2014 - Intel SSE Intrinsics Applications in Rudimetary Matrix Algorithms
        • 2014 - LIFC to MIPS Compiler and Assembler
      • Web Development >
        • 2014 - Javascript Calendar
        • 2014 - Multi-Room Chat Server
      • Graphics >
        • 2015 - Basic Animation w/ WebGL
        • 2015 - Diamond Square Terrain Generator
        • 2015 - Flight Simulator w/ WebGL
        • 2015 - Multi-Program Texture Mapping WebGL
      • Software >
        • 2015 - Consumer Grade Gaze Pattern Recognition Software
        • 2015 -Test History Jenkins Plugin
      • Other >
        • 2014 - Hashtable for Genomic DNA Sequences
        • 2014 - Closest Pair of Points
    • Virtual Reality, Game Design, & Animation >
      • 2019 - Interactive Music Visualization
      • 2016 - Visualizing Runtime Flowpath in VR
      • 2016 - Fiducial Marker Tracking for Augmented Reality
      • 2015 - Experimenting with PhysX & APEX Destruction
      • 2015 - Rigging Tank Treads using MEL in Maya
      • 2015 - Automated Simulation Teddy Bear Bin
      • 2014 - Networked Multiplayer Game of Set
      • 2014 - Asymmetrical Multiplayer Destruction
      • 2016 - Tracking & Depth Perception
      • 2014 - 8 Week Game Design (Cave Survival)
      • 2015 - Experimenting with Nvidia FLEX
    • Computers >
      • Custom and Watercooled PCs
      • Component Reviews
      • Installation Guides
    • Quantitative Physiology >
      • Computational >
        • 2015 - Modelling Neurons & Action Potentials
        • 2015 - Simulating Neuronal Learning during Brain-Machine Interface
        • 2014 - Imaging: Rabbit Optical Mapping
        • 2014 - Simulating Electrical Stimulation w/ Comsol
        • 2014 - Ion Channels
        • 2013 - Designing Filters to Simulate Olfactory Sensation
        • 2014 - CardioVascular Mechanics
        • 2014 - Renal
        • 2013 - Principal Component Analysis & Singlar Value Decomposition
        • 2013 - 3D Printed Frog Muscle Holder
      • Physical >
        • 2013 - Biomedical Signal Acquisition
        • 2013 - Electrooculogram
        • 2013 - Compound Action Potential in Frog Sciatic Nerve
        • 2013 - Contractile Properties of Frog Skeletal Muscle
        • 2013 - Locust Olfaction
        • 2014 - Voltage Clamp
        • 2013 - Dive Response
        • 2014 - Frog Heart Muscle
        • 2013 - Ultrasound
        • 2014 - Biological Signal Conditioning
        • 2014 - EKG, Vector Cardiograms & Pulse Wave Velocity
    • Electrical Projects >
      • Self Balancing Robot Pendulum
      • Custom Beer Pong Tables
      • 4-axis Robotic Arm
      • Modified Electric MiniBike
      • Secret Knock Detecting Automatic Door Opener
      • Car Audio
      • Tree-House Wiring
      • Laser Harp
    • Auto & Mechanical Projects >
      • Single Turbo Lexus SC300
      • Track Day Mx-5
      • Karting
      • Racing Simulator Rig
      • 50cc Barbie Jeep
    • Random Other Projects >
      • Talk: Embodied Cognition
      • Bathymetry Coffee Table
      • Not your average Tree House
      • Pneumatic Tennis Ball Cannon
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Automatic Secret Knock-Detecting Door Opener
(2014)


A few secret knock detecting Arduino projects exist around the web, meaning the basic micro-controller logic for the knock sensing function has been fleshed out. With confidence that the software end would work, I set out to build a secret knock detecting door opener that would open my door if provided a secret knock.

Idea

​My original plan was to interface with the electric deadbolt in my apartment door, but upon inspection the unit is upwards of $900... and I'd prefer not to take any chances messing with the internals. A bit less elegant is a mechanical system that would open the door by the door handle itself. Since the project requires no finesse or accuracy in motor control, I figured a cheap high torque servo motor flipped through a pulley would likely do the trick. An MG995 13Kg-cm high torque servo costs about $6-7 and can be modified for full rotation. I designed a custom winch system to pull the door knob open.

Basic Circuit

Picture
Because the Arduino handles all the analysis and control, the circuit is relatively simple. I've sketched it out on the right. A variable potentiometer allows the sensitivity to be adjusted and the LEDs indicate success or failure of the knock for debugging purposes.


Prototyping the Arduino Shield

Picture

Finalizing and Rebuilding a Reliable Shield

Picture

Designing a Winch System

Parts Used:
  • MG995 13kg-cm Servo Motor modified for full rotation
  • Servo Winch Drum Modified to fit the MG995
  • Picture Frame Hanging Wire
Picture
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