Ag Robot

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A sponsor is facing a situation in which it would be useful to have a remotely-controlled robot to drive up and down rows in a greenhouse and make cuts into a plastic tarp covering the soil. I expect that this would be a fairly simple robot with tank drive, pneumatic wheels (8" probably okay), a rotating knife assembly to do the cutting and a camera to facilitate driving. I don't guess pneumatics are needed. The sponsor would subsidize the cost of the robot, which I expect would not exceed $5,000 (x-shipping).

I've discussed this with the sponsor, and they are enthusiastic about the project.

I think that this is a good summer project for us as well (although I wish we didn't have so much on our plate already). I think it's also a really good E.I. story line.

As a not-FIRST robot project, we have some additional flexibility with components.

I've put together some assumptions and questions for this project (attached) to help in setting clear objectives and specifications. Any editions or additions to this list would be welcome.

Starting Assumptions

  • Robot will be remote-controlled (not autonomous), wheeled vehicle
  • Driver will have video stream to guide driving
  • 12 VDC battery power supply – no voltage >24 VDC
  • Wireless communications - No tether
  • Not XP
  • A switched Main Circuit Breaker will turn robot on and off. The switch will be easily accessed, but protected to avoid accidental tripping.
  • An easily-observed light will indicate that the robot is powered
  • The Main Breaker will supply a Power Distribution Breakout which will power all power users on the robot via individually fused (circuit breaker) terminals
  • All wires will be copper
    • 6 AWG for 120 A protected circuit
    • 12 AWG for 31-40 A protected circuit
    • 14 AWG for 21-30 A protected circuit
    • 18 AWG for 6-20 A protected circuit
    • 22 AWG for ≤ 5A protected circuit
    • 28 AWG for Signal Level Circuits ≤ 1A
  • Constant polarity non-signal wires will be typically color coded red for positive, black for negative or common
  • Electronics will be shielded from dripping water; not against immersion
  • Battery removable/replaceable for recharging
  • Battery to remain in overturned robot
  • Battery indicator on control panel

Initial Questions

  1. What’s the maximum area that would need to be cut in a single mission?
  2. Maximum distance between controller and robot?
  3. Desired cutting pattern?
  4. Is Lead-Acid Battery okay? VRLA (Valve-Regulated Lead-Acid) okay?
  5. What is maximum weight?
  6. How will this be carried? Transported?
  7. Are there size limitations?
  8. Cleaning between missions?
  9. Is collision avoidance necessary?
  10. Metric or SAE bolts?
  11. Can Arkema Inc. ship?
  12. Necessary completion date?
  13. Control preferences
  14. Visuals? Labeling?

Mazarrón, Murcia, Spain

The Mazarrón application is a little weird for a couple of reasons. First, the tarp and driplines are sometimes perpendicular to each other. Parallel is normal. Second, the joining of adjacent tarp sections is raised and stapled. Normal is glued and/or buried.


More typical applications.

Spec Meeting - 8-June-2018

Attendees: Thierry Fouillet, Nathalie Julien, Gael DuFretay, Andrew Horvath, Clem McKown

From the Objectives list, all “Starting Assumptions” were verified.

1. Maximum Area or time for cutting mission?

One hour operating life with battery desired. Field sizes can be 0.5 Ha to 10 Ha.
Robot velocity 1 – 2 m/s considered acceptable.

2. Maximum distance between controller and robot

Not addressed.

3. Desired cutting pattern

Cuts to be between drip lines. Drip lines are 1.0 – 1.5 m apart.
Broadcast tarps are not stretched. A tensioning roller may be needed.
Thierry will send a 2 x 2m sample of tarp by air now. (1) roll of tarp approx. 2 m x 800 m for July delivery.
Need to understand that there may be rocks and other objects in soil.
Knives should easily cut tarp, not cut drip lines.

4. Is Lead-Acid Battery okay? VRLA battery okay?

To be verified.

5. What is maximum weight?

40 kg. Actual need : liftable by two persons.

6. How will this be carried? Transported?

Back of pick-up truck.

7. Are there size limitations?
8. Cleaning between missions?

Knives will need to be cleaned. Maybe wheels? Both should be easily cleanable with hose. If razor blades used for cutting, need to be easily changed.

9. Is collision avoidance necessary?

No, but bumpers are desired.

10. Metric or SAE bolts?

Must be metric.

11. Can Arkema Inc. ship?

We’ll work with that assumption.

12. Necessary completion date?

August is the peak season. Also impractical. October for Trial suggested.

13. Control preferences?

DAR to propose.

14. Visuals? Labeling?

Yes. Accolade theme.

Other points: Reliability, durability and low maintenance are essential. This is a working robot.

We’ll meet every 2 weeks for progress review. Friday 10:00 am Philadelphia (16:00 CET).