Energy and power budgets

Robot Talk
1

From a vehicular system perspective, at some point one has to think about how much power and daily energy will be generated, which will depend upon;

  • Solar array output rating
  • Location’s monthly average solar insolation (instead of simply latitude)
  • Cloud cover for the day

Then the power and energy budget can be roughly apportioned to individual subsystem components;

  • Electro-mechanical
    – Drive motors
    – Steering motors
    – Robotic arm(s) and tools
  • Electronic
    – Processing unit (including memory and storage)
    – Communications (GPS, and any of wifi, bt, etc)
    – Sensors (Camera)
  • Energy storage
    – Battery (if a small one is desired to smooth out frequent partly cloudy day dips, a medium size one to smooth out daily variation [start sooner, end later, etc])

The various use cases can have very different power budgets, such as weeding, planting, level ground vs. slope, etc, as well as different locations providing very different solar inputs (e.g., So. Cal vs. Vermont)

There is also the subject of modes, as it will invariably have at least two basic modes;

  • Operating: Able to move about, plant, cultivate, etc because sufficient power is being generated (or pulled from a battery, if so equipped). When sufficient power is no longer available (or when the battery reaches a predetermined discharge level), it transitions to Dormant.
  • Dormant: Awaiting the moment the morning’s sun will be sufficient to transition back to Operating mode (or when the pre-determined start time is reached, because a specific amount of charge was left in the battery to begin morning duties). In Dormant mode, it is either fully off, or in a very low power draw mode.
1 Like
2

I’m used to larger fields with multi-row implements and bigger tractors, where weight, traction, and power are optimized to pull a planter or mechanical cultivator through the soil for each row.
800W is about 1 hp. How much pull force can you get from Acorn?
For example have you tried putting a single cultivator blade in the ground to see if Acorn can pull it?

2 Likes
3

Thanks to the supercapacitors, Acorn can provide high peak power. I have a bunch of data in our database about it (every meter of travel acorn records a bunch of energy data). I think I’ve seen peak loads of 4kW when pulling a heavy roller.

Our goal with this machine is to avoid tillage as much as possible, so we are targeting a minimal tillage system. It may be helpful to be able to attach a gasoline power plant for certain high power operations, but we will be focused on trying to get farming done with low energy usage.

2 Likes
4

Maybe this project or some ideas from it could be used for Acorn; DIY 1kW Arduino MPPT Solar Charge Controller (WiFi ESP32) - YouTube

1 Like
5

Hi @taylor, @Twerpoid_M, @WillStewart,

Whilst I’m very strongly in favour of no tillage, it may be wrong to assume other critical natural organic, regenerative permaculture style farming functions don’t take large amounts of energy. ‘No-till’ alone, is not regenerative enough in most farm cases.

Especially if we want to feed a few families, have high nutrient surplus and provide valuable community engagement/employment, to the scale needed to replace industrial destructive farming. I’ve listed a few implements …see: Requirements Backlog.

Thanks @Twerpoid_M in rating 800W to 1HP, meaning a small compact 30 to 40HP tractor needed for most basic implements is: 24kW to 32kW.

Some v.light tillage is often necessary. Light ripping (not plouging), on contour for oxygenation, water spreading/soakage, drought proofing, fire resistance, decompaction, deeper root penetration, cover crop seeding…

Crucial Spraying of foliar and ground sprays. Neem, or other organic fertilisers/foods based on beneficial soil life profile. A weight of 530kg to 1100kg liquid tank payload plus 300kg sprayer implement is a 830kg to 1,400kg towing capacity and PTO energy and hydraulics power, required to run it.

Critical Mulching using a Flail Mower/mulcher, (or brush-hog/slasher), for sequential/rotational cropping, grazing and cover cropping. A weight of 300kg towing capacity and PTO energy and hydraulics power, required to run it.

Simple Spreader for seeds, soil ammendments, etc for compost, activated biochar, ag lime, muck, etc. A weight of approx 250kg+ tank hopper storage plus 200kg for the implement, so towing capacity of 450kg, and PTO energy and hydraulics power, required to run it.

If that helps give an idea of payload and towing capacity, we may need to yet do the calculations for PTO and hydraulics power requirements. But assume 24kW to 32kW. My 30HP struggles badly and I was thinking of getting a 40HP for smoother continuous and shorter runtimes without having to redo sections because it didn’t mulch properly.

Cheers,
Raj