Alden’s Status report for 10/3

Accomplishments

Repeater node characterization — electromagnet and power

Worked to characterize the electromagnet.
Determined the boost converter that will be used: Pololu 5V Step-Up Voltage Regulator U1V11F5 (item #2562).
Established the minimal weight of the relay as a T-beam Supreme, 915 MHz antenna, Pi 0W, 18650 battery, and boost converter (battery voltage → 5V for the Pi 0W):
- T-beam Supreme: 100 g
- 915 MHz antenna: 30 g
- 18650 battery: 50 g
- Pi 0W: 10 g
- Boost converter: 1 g
- Total component weight: 191 g
Assume the final weight will be more like 2× that, so assumed 0.5 kg as the worst case for casing and wiring.
The electromagnet can hold that weight.
Maximum current draw of the electromagnet is 300 mA.
Still need to work out what current draw can hold what weight.

Roving bot control software

Planned the implementation.
Wrote code that will be used to test the motors we bought.
- Focused on things that are not reliant on the constants we do not know; the PPR of the encoder and the PWM → motor speed mapping are the two most urgent.
Wrote code to integrate with the SLAM software (still not back from Ben).

Have not yet determined the current draw required to hold a given weight — this is the core of the electromagnet characterization.
SLAM software is still not back from Ben, so control software integration with SLAM could not be done.

Find the current draw that can hold 0.5 kg. Should not need to draw 300 mA continuous.
Work with Ben on the solenoid-based actuation.
Hopefully have the SLAM software; work to integrate and test it. Hopefully will be able to integrate the control software into SLAM testing as well as SLAM software integration on the physical bot.
Characterize the motors and use that calibration data to expand on the code.

Worked on the deployment mechanism for the repeater node.
- Determined the best way to detach the repeater node from the rover.
- Considered several mechanical solutions.
- Along with Ben and Ethan, determined that the best option is an electromagnet to detach the node.
  - The electromagnet will be on the rover and attach to a ferromagnetic portion of the node hardware.
Worked on the physical construction of the electromagnet:
- Researched the design of electromagnets to maximize hold force for a given current draw.
- Identified a ferromagnetic core.
- Modeled and 3D printed a wire wrap guide prototype to hold a wire wrap to the core.
- Wrapped the prototype.
- Have yet to test the hold force of the electromagnet.

Meant to characterize the electromagnet but was unable to.
Meant to continue the work Ben started on the SLAM simulation, but he was still cleaning up some stuff, so I wasn’t able to work on it.

Social factors relate to extended social groups having distinctive cultural, social, political, and/or economic organizations.
They have importance to how people relate to each other and organize around social interests.
Social factors are a major concern:
- The autonomous nature of the project opens the possibility for the technology to be put to use in military use.
  - This is not an intended effect.
  - Mitigated by the mesh network not including any resistance to signal interference or blocking.
- The technology may not be available in places without the money to build or buy this technology.
  - Mitigated by the low cost and generic nature of the rover.
  - The base technology does not need a specific form factor or movement type, so the rover can be replaced with a different rover depending on use case and resources available.
  - The $600 budget is much more achievable than comparable industry solutions, which can cost thousands of dollars.

Researched the motors we ordered and worked on the control system.
Focused on the power and control electrical and logical protocol, working on the power system that will power the motors.
Worked with Ben on the compute power system:
- Determined how to power the Raspberry Pi from the LoRa power system via a boost converter.
- Planned the motor power system (battery → motor).
- Ultimately decided to run the motors directly off of the battery voltage.

Was unable to nail down the motor control mechanism due to missing information on the online listing.
- We have to wait until the motors arrive.

Used AI to crawl the internet and attempt to find the logical protocol for the motors after a manual search of the online listing failed.