Use flow

Use flow


The electri-critter is a small robot vehicle that follows the walls in a home and senses electric loads (the current flowing in the power cables). When it approaches a power cable, it clamps its sensor onto the cable and measures the load. Because the current transformer (CT) reports different signal levels depending on the relative orientation of the conductors within the cable, the CT must be rotated around the cable until the best orientation is found. The critter will then be able to sense when the appliance turns on and off, and ideally the size of the load. The critter will eventually traverse the entire house, cataloging as many loads as possible.


Alternate version: an augmented reality device which a person uses to move through their house and discover the energy consumption of various devices by turning them off and on. Unlike other similar solutions, it would not require the user to unplug the device or record any numbers, because it would sense induction fields around the device’s cord (or perhaps even further) and measure power consumption using a whole-house energy meter that the device communicates with.

Low-bar target: device can be handheld, manually attached to cord, communicates to central meter and receives accurate power consumption, which it then displays to user.

High-bar target: Device may not need to be attached to cable, but only in vicinity of appliance; device may help direct user (or self) to location of cord; feedback may include on-screen (of PC) time-based graph or representation of whole-house energy consumption with the target appliances portion highlighted; multiple devices all simultaneously communicating with central meter… ?


  • Signal processing / event detection – to identify relevant transitions from the mobile current sensor
  • Mechanical design and fabrication – to create an integrated hinge actuator and closure sensor 
  • Soldering and circuit testing – to assemble XPort ethernet board
  • LCD interface – to output Watts on mobile sensor


  • Central electricity metering system (I happen to have a couple installed already)
  • Current transducer (I also have some of these)
  • LCD numeric output (need to purchase multi-digit, or I think Hammerschlag has some one-digit models)  
  • wood/metal/plastic disks, gears, hinges, and such – to make cable-clamping and critter-rotating assembly
  • Network connector for Arduino (I have an Xport Ethernet board, but wireless would be better) – to communicate with central meter
  • Microphone for Arduino – to take user input and describe the appliance which is being used


  • Week 1: rough draft of mobile device event detector; serial communication to central meter; attempt to correlate events
  • Week 2: rough draft of current-clamp rotating apparatus; ethernet board for Arduino, and communication code for both ends (sensor andrew?) 
  • Week 3: user interaction on Arduino – indicate power consumption, events detected and displayed, accept user labels for events; attempt to calculate power without central meter, using rotation
  • Week 4: attempt wireless, add PC-based energy consumption display, make device more robust, add autonomous vehicle?

Sketches to come (after scanning)…