156B Week 2

Progress Since Week 1

Hardware Assembly

• Hardware Meeting 1 & Hardware Meeting 2

• Purchased more materials including bucket, soil, pulleys, and swivel hooks

• Built a pulley attachment system using FarmBot Components like the Cable Carry Support

• Mounted the motor to an extrusion using the Gantry Corner Bracket

Design Updates

• Brainstormed a way to utilize the Z-axis Cross Slide Plate as a mounting mechanism for cables and UTM

  • Cross Slide Plate is made of stainless steel - which poses issue to modification with hand tools

UTM & Cable Adapted to Cross Gantry Plate

Software Updates

• Current code rewritten to control 3 stepper motors from single Arduino

• No movement logic can be implemented within FarmBot code by rewriting G-code handlers and passing new parameters to movement functions

Materials to Buy

• Spools (wooden or plastic?)

• Aluminum extrusions

• Larger swivel hooks

• Braided Polyester

Current Concerns (decreasing priority)

1. Where can we quickly obtain aluminum extrusions needed to stabilize our system? FarmBot sometimes takes an upward of two weeks to deliver components. If we can’t order from FarmBot in a timely manner, is there any way we can order the components from McMaster Carr through UCSD?

2. In the Cross Slide Plate to UTM/cables mounting design, we need to modify the Cross Slide Plate to cut holes or widen holes to fit components the way we have created our design. However, the Cross Slide Plate is made of stainless steel. If we were to use aluminum plates so that the component is more easily modifiable with common hand tools, it may be susceptible to corrosion and oxidation due to weather exposure. What material should we select for the plates if we would like the plates to be (1) soft metal that is easily modifiable with hand tools and (2) robust to weathering?

3. When modifying and assembling components, we often use hand tools. How can we incorporate safety measures and advisories for non-engineering users when they assemble our system?

4. There has been a heavy focus on soil penetration and reaction force for this project, prompting a deeper look into soil penetrometers and force measurement tools. However, after review of the FarmBot end effectors for seeding and weeding, which use needles to penetrate and implant the seeds, it has been determined that reaction force will not be a major area of concern considering the geometry of the needle and the loose soil type typically used in gardening plots.

Feedback from Meeting with Instructor

• Upload media directly to Website from computer instead of from Google Drive to bypass privacy issues - COMPLETE

• Be sure to order items well in advance

• Determine most optimal and efficient method of reimbursement - COMPLETE

• Look into soil penetrometer suggested by Tom - COMPLETE

• Be more specific with our current concerns - develop any questions we may have for the instructional team during the weekly meeting - COMPLETE

Feedback from Meeting with Sponsor

• Reimbursement process - get reimbursed directly from Nick by filling out and sending him the reimbursement form

• Primary focus: positioning

• Secondary focus: functionality of end effectors

• FarmBot delivery: one component is faulty - waiting on a replacement component

Upcoming Goals

Weeks 3-5

• Fix swivel hook to pulley attachment

• Stabilize the system using horizontal extrusions as reinforcement

• Finish construct system, mounting all motors, spools and pulleys

• Test positioning accuracy with only 3 stepper motors and current code

  • Use tape to create a grid that helps to visually assess positioning accuracy

• Work to convert FarmBot code from interpreting Cartesian coordinates to barycentric coordinates

Weeks 6-8

• Motorize the fourth motor/cable and adapt code to incorporate all four motors in positioning

• Assemble UTM and cables to plate

• Motorize end effectors for functionality

• Electronic Cable management

Budget Remaining: $2325.31