Design in Progress
BenchBot V3 is a clean sheet design and will not specifically inherit any design aspects of previous versions.
Project Goals
Build a robust and capable robotic system for carrying the image acquisition payload in its execution of the image repository project.
Work well in all expected semi-field conditions.
Exceed the performance of previous versions of BenchBot.
Throughput
Reliability
Autonomy
Be capable of fully automatic operation without an operator on site.
Be robust enough to withstand direct exposure to the elements for multiple seasons with reasonable maintenance.
Be straightforward to assemble on site with available resources.
Field configurable to various site sizes.
Not require significant specialized trades on site.
Support future payloads in addition to the image acquisition system.
Working Assumptions
BenchBot and the Image acquisition system will be treated as separate but connected systems / projects. BenchBot Tool Interface - BenchBot - Confluence (atlassian.net)
They must work together through a defined electrical, mechanical, and control interface but will not have their designs intertwined unnecessarily.
V3 Image Acquisition System Requirements - BenchBot - Confluence (atlassian.net)
The system will be based on the Amiga robot from farm-ng.
This will save considerable development and manufacturing time by essentially providing a fully electrically / mechanically functional Y axis.
PSA (Mark Funderburk ) will design the gantry structure and X Z motion hardware partially using electronics hardware from farm-ng.
Farm-ng will develop an API to control the BenchBot through simple go-to X Y Z commands.
PSA will be developing any other custom hardware needed for BenchBot that farm-ng was not already developing for other applications.
PSA software development will be beyond the API level and contained withing the scope of the payload project.
Project Requirements
These requirements are derived from evaluating the performance needs of the Image Acquisition System (IAS) + other applications the BenchBot hardware may be utilized for in the future. However, the IAS is currently the primary payload of the BB and thus the requirements here will be designed to meet the minimum needs of the Image Repository project with additional applications considered where it will not interfere with IAS needs.
The value of many of these requirements is derived from existing semi-field scenarios to be sure we can make the most of the space and resources available.
Summary | Description | Allowable Limits | Status |
|---|---|---|---|
Axis of Movement | Shall provide 3 integrated axis of movement X, Y, Z. | True | Draft |
Tool Head | Shall provide standard electrical & mechanical interface for mounting a toolhead (such as a camera or actuator). | True | Draft |
Tool Head Positioning Range | Shall be capable of positioning the tool head anywhere in an operating envelope defined by X, Y, Z dimensions offset by minimum or maximum height from the operating surface. | True | Draft |
Tool Head Position Accuracy | Shall be capable of positioning the toolhead in the operating envelope to this degree of accuracy. | +/- 1cm > PA | Draft |
Wheel Track Position Accuracy | Shall be capable of positioning the wheel track in the operating envelope to this degree of accuracy. | +/- 10cm > PA | Draft |
Tool Head Mass Light | Shall be capable of supporting a tool head of at least this mass in all operating areas. | 10kg < M | Draft |
Tool Head Mass Heavy | Shall be capable of supporting a tool head of at least this mass in all operating areas. | 50kg < M | Draft |
Assembly | Shall not require significant specialized labor to assemble onsite. | True | Draft |
Gantry Width Configurability | Gantry width shall be field configurable to a specified range without major design changes. | True | Draft |
Min Configurable Gantry Width | Gantry shall be configurable and fully functional / structurally sound to at least this width. | W_max >=6m | Draft |
Max Configurable Gantry Width | Gantry shall be configurable and fully functional / structurally sound to as little as this width. | W_min <=2m | Draft |
Basic System Diagram
Detailed System Diagram
Key | Summary | Description | Allowable Limits | Status |
|---|---|---|---|---|
Axis of Movement | Shall provide 3 integrated axis of movement X, Y, Z. | True | Draft | |
Tool Head | Shall provide standard electrical & mechanical interface for mounting a toolhead (such as a camera or actuator). | Draft | ||
Tool Head Positioning Range | Shall be capable of positioning the tool head anywhere in an operating envelope defined by X, Y, Z dimensions offset by minimum or maximum height from the operating surface. | True | Draft | |
Tool Head Position Accuracy | Shall be capable of positioning the toolhead in the operating envelope to this degree of accuracy. | +/- 1cm > PA | Draft | |
Wheel Track Position Accuracy | Shall be capable of positioning the wheel track in the operating envelope to this degree of accuracy. | +/- 10cm > PA | Draft | |
Tool Head Mass Light | Shall be capable of supporting a tool head of at least this mass in all operating areas. | 10kg < M | Draft | |
Tool Head Mass Heavy | Shall be capable of supporting a tool head of at least this mass in all operating areas. | 50kg < M | Draft | |
Assembly | Shall not require significant specialized labor to assemble onsite. | True | Draft | |
Gantry Width Configurability | Gantry width shall be field configurable to a specified range without major design changes. | True | Draft | |
Min Configurable Gantry Width | Gantry shall be configurable and fully functional / structurally sound to at least this width. | W_max >=6m | Draft | |
Max Configurable Gantry Width | Gantry shall be configurable and fully functional / structurally sound to as little as this width. | W_min <=2m | Draft | |
The concept design is for a 30ft wide gantry, but it can be configured in many widths, definitely smaller and possibly larger with further engineering verification.
pot height: 25cm + 40 cm + sensor min distance
Ask Lirong about what size plants she needs to use.
Cost Estimation
Component | Cost estimate | Link / info | Notes |
|---|---|---|---|
Amiga Robot Base Unit | $13k | ||
F34 Square Truss 3m straight segment (9.8ft) | 2 x $ 506 = $1012 | Global Truss Straight Square Segment for F34 Square Truss (bhphotovideo.com) | Lots of other distributors for compatible truss (Keyword F34) |
F34 Truss 6-Way Junction Block | 2 x $392 = $784 | Global Truss Universal Junction Block (Silver) ST-UJB-12 B&H (bhphotovideo.com) | |
F34 Square Truss 2m straight segment (6.6ft) | 2 x $392 = $784 | Global Truss Straight Square Segment for F34 Square Truss (bhphotovideo.com) | (Configure this to alter gantry width) |
3M Horizontal linear rail guide | 2 x $852 = $1704 | IVTAAQ Bolt-On Integrated Linear Guide - Double Width (pbclinear.com) | (Configure this to alter gantry width) |
3M Horizontal linear rail carriage | $412 | IVTAAQ Bolt-On Integrated Linear Guide - Double Width (pbclinear.com) | |
2M Vertical linear rail guide and carriage | $760 | IVTAAG Integrated Linear Guides - Integrated Aluminum Extrusion (pbclinear.com) | (Configure this to alter gantry height) |
Horizontal Travel Servo Motor | $350 | TBD Exact Part | |
Vertical Travel Servo Motor | $550 | TBD Exact Part | |
Equipment Box | $200 | TBD Exact Part | |
Linear guide mounting bracket | 26 x $20 = $520 | Laser cut Aluminum/steel plate (send-cut-send) | Design Not Finalized |
Truss Base Mounting Plate | 4 x $117 = $468 | Laser cut Aluminum/steel plate (send-cut-send) | Design Not Finalized |
Horizontal Drag Chain | TBD | ||
Vertical Drag Chain | TBD | ||
Current Total Estimate (will go up): | $7,544 + $13k = $20,544 |
Motion Components
Horizontal linear motion will be done with timing belts. As this is the most cost-effective way to make a repeatable weather resistant setup.
Vertical Motion will be accomplished with a stainless-steel lead screw. These are surprisingly affordable and offer the corrosion resistance and load capability we need.
Component | Cost estimate | Link / info | Notes |
|---|---|---|---|
304 Stainless Steel Precision Acme Lead Screw | $154 | ||
Plastic Externally Threaded Precision Acme Nut | $42 | Plastic Externally Threaded Precision Acme Nut, Right Hand, 3/4"-6 Thread Size | McMaster-Carr | |
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