Overall Project Plan

Requirements (not specifications)

  • To Be Written

Approximate Project Phases

Not all of these phases may be taken to completion, but they represent the approximate trajectory for the project and serve to help organize outstanding questions such that they can be tackled in a reasonable order.

Phase 0 – Pretotype

  • Is this something rowers are interested in?

    • Is there interest from the market in people buying this?
    • Is there interest from people to help develop this?
    • Could this be marketed to gyms as an add-on to ergs? A la thegreenecogym?

Phase 1 – Collect Baseline Measurements

  • Flywheel

    • How much energy does the flywheel have?

      • How fast does an erg flywheel spin?

        • From the WPI paper: peaks at like 800 RPM (not clear if this is absolute max though). RPM ranged from 395 to 780 and angular velocity ranged from 41.36 to 81.68 radians per second

        • Use an Optical tachometer and arduino to datalog it (maybe there’s a better way and the data can be crowdsourced)

      • How heavy is the flywheel?

      • How much is air resistance affecting the flywheel

      • How much torque?

        • From WPI paper torque peaked at about 15 NM

      • How does the flywheel connect to the axle that drives it?

        • Is it a standard connection?
  • Rower

    • How much total energy is being put into the erg from the rower/handle? (this is useful for calculating the efficiency of thewhole system)

      • How much is going into the elastic versus the flywheel?

    • What speed is the handle moving at?

  • How can we collect this data while the flywheel cover is closed while allowing the side dial for drag to be changed?

    • Possibly drill a small hole in the mesh for passing cables? - a single twisted pair of ethernet cable or similar should be able to fit through the holes in the flywheel, if not just one cable. should be enough to get the relevant data out

  • How much power/information does the built-in cable/motor thing provide?

    • Not much power at all, and it probably cant be used as the existing monitor needs it
    • informatin wise it may be better to use the Concept2 SDK as the monitor does a lot of the processing of that signal for us
  • come up with a set testing workout (step workout?) to test how it works at various rates and powers
  • may also be nice to have a way to consistently pull the handle at certain speeds/powers to test the resistance consistently
    • this might be able to be accomplished by droping a wight that’s tied around a pulley and using gravity to pull the handle sideways in a repeatable manner
  • is there an effective way to crowdsource data from people who are interested in this and have the tools to do so (so I dont have to spend tons of money on all the tools)

Phase 1.5 – Research

  • What are concept2’s units of Drag Factor? Is it based on the air resistance?

    • Constant force or no?
  • what rpm/torque value is best for power generation?

  • How does the concept2 “watts” measurement compare to actual power generation? Is it heat watts vs energy watts?

  • What type of motor is likely to be best for converting the flywheel motion to electricity?

    • BLDC

  • Do we need a gear system to get more motion, less force, or more force, less motion?

    • I think this depends on the motor as we’d need to match it’s RPM/torque for optimal output

  • Is it possible/are there devices that exist to control the power draw on a motor digitally? (i.e. with an arduino?)

  • Is there a version of Concept2’s SDK that suports linux?
    • how about third party implementations
    • can it really be anything platform specific that cant be recompiled or something? like as far as i can tell it should just be interfacing with the monitors via bluetooth/serial
  • What has Concept2 changed year to year hardware wise on the ergs? (specifically Re: flywheel) anyhing major that affects this project?
    • i suspect that the device that measures the flywheel’s speed/sips power for the monitor changed from the PM2 to the PM3 ergs as i believe thats where they introduced the idea of the flywheel powering the erg while its in use.
      • This seems to be supported by higher numbers in/between experiments 1 and 2 but not 100% sure as those experiments were poorly conducted and not super on-topic
    • would be nice to get datasheets for these parts
  • What are the units on the force curve?

Phase 2 – Basic Experiments

  • How does the data from phase 1 vary when the flywheel cover is on vs off?

  • How does the data from phase 1 vary when the flywheel cover is covered/sealed as best as possible versus sitting there regularly?

  • How does the data from phase 1 vary when the drag factor dial is changed?

    • This will help calibrate the system to match Concept2’s drag Factor later

Phase 3 – Prototyping/more experiments

  • How efficient can we expect the conversion from motion to electricity to be?

  • Can this generated power be used for simple stuff (powered speakers, charge phone, charge battery, fan???)? (is there a usable amount of power generated?)

  • What affect does taking more power from the flywheel have on the drag factor. How about the erg’s ability to power itself?

  • Do we need to make the flywheel heavier?
    • How do you make the flywheel heavier (safely/in a balanced way)?
      • Put a chain around the edge?
  • How to prevent the existing fins from slowing the flywheel down via air resistance?
    • Create a new flywheel that can be swapped out?
    • Cover the fins?
  • How best to connect the motor to the flywheel?
    • put gear-like teeth or some other grippy surface (like a rubber-wheeled LEGO wheel for testing purposes) around the circumference of the flywheel (either facing outwards like a regular/bike gear, or to with the teeth facing the face of the flywheel) so that there is a gear-like relationship between the flywheel and the motor shaft
    • put a belt around the edge of the flywheel and use that to drive a motor located elsewhere
  • Can we use the concept2 SDK for logging data? (watts, s/m, drag factor, flywheel RPM, etc?)

Phase 4 – Refine

  • Can we collect power while keeping the resistance somewhat the same (minimal modifications to the flywheel cover?)?
  • How much energy can be taken out from the flywheel and used while still having the erg be not significantly harder to use?
  • How to calibrate the resistance provided by the new system so that it matches the air-based/Drag Factor based system

  • Can this generated power be (safely) fed back into the house’s power grid?

  • Can the resistance be customized either with a dial or through software by drawing more current/power from the flywheel?
    • Could we just seal the flywheel cover to remove as much air resistance as possible and just control drag factor with power draw?

Phase 5 – (Possibly) Commercial Development

  • Can we collect power in a way that can be easily added/removed from ergs? (i.e. as a replacement flywleel/replacement flywheel casing that the user can swap out)
  • How cheaply can this all be done?
  • What regulations will we need to comply with in order to sell this?
    • possibly EM Interference, UL Listing, others?

Phase 5.5 – Operations and Support

  • What will be neded to support this product?
    • manual? install guide?
  • What would operations look like?

Phase 6 – Future Complimentary Products

  • Can other sources of power (gutter/rainwater generators, etc) be used to augment the power from the erg to add more ways to power a house? (this is kinda the ultimate vision)
    • Convert a real bike? (greenmicrogym already did this)

Research, Ideas and Brainstorming

Parts and Sourcing

Monitoring Devices

  • https://www.thegreenmicrogym.com/2013/09/05/ensupra/
  • Kill-A-Watt or similar watt meter for the wall once we get to the stace of putting power into a house

Energy storage

  • ultracapacitors?
  • https://www.thegreenmicrogym.com/2013/07/08/diy-off-the-grid-with-the-upcycle-eco-charger/
  • https://www.thegreenmicrogym.com/2015/07/13/the-history-of-the-upcycle-ecocharger-how-it-came-to-be/
  • Batteries
  • 18650’s?
  • battery charge controller/s
  • safety shutoffs/containment for anything that can explode

Energy Conversion

Inverter

  • Power conditioning system (probably built into the inverter???)

Rectifiers

Motors:

Option 1: homemade (WPI did this)

  • magnets x lots
  • copper wire x lots
  • some disks to mount to the flywheel axle
  • oh dear oh god how to keep it balanced
    • measuring. lots of measuring
  • nope

    Option 2: Purchace new/used

  • BLDC
  • treadmill motors (would 90v work? seen that number somewhere)
  • ebike motors

Option 2.5: use something that exists

  • Tacx bikes (https://www.ebay.com/itm/Tacx-Cycleforce-T1670-Bike-Trainer/324395584540?hash=item4b877bcc1c:g:vv8AAOSwPktfws-D)

Physics

Planning

Ideas for Ways to connect motor and flywheel

  • belt
  • chain
  • gears
  • fabricate a new flywheel that mounts the same way as the stock one?

Misc

World records for erg power generaton

  • https://phys.org/news/2012-07-world-rowers-electricity-power-house.html