Author: cbayley

This week I completed the assembly file of the gantry design and made several modifications to the originally designed parts. Some of these modifications included a complete redesign of the bearing holders, a redesign of the print head to hold a servo vertically, and modification of the frame to move beams to the top. The assembly file is shown in the gif below.

 

Additionally I began printing some of the parts and made some modifications based on the results. We have received the shafts which run along the perimeter of the design and have been able to fix the pulley to the shaft using a small screw. A good portion of my time this week was also spent working on the design report.

This week I remained mostly on schedule, but made an ordering mistake last week which resulted in us not receiving our raspberry pi which slowed us down a bit for this week. I am still mostly on schedule, and plan on completing all designing and 3D printing of the remaining parts.

This week, we finalized the design for our 2D gantry system, as well as the frame of the robot. We started ordering many parts, including the Raspberry Pi, the motors, a paint set, and shafts and bearings for the axis system. We worked on our design review presentation, and created several diagrams and schematics for it. In addition, our team met with Professor Aswin Sankaranarayanan to get input on the image processing aspect of our project and discuss our software algorithm.

The most significant risks of our project continue to include the success of our 2D gantry system, which was discussed in last week’s report. We will continue with the plan we have in place, with our backup plans still ready. Once the parts we’ve ordered have arrived, we can begin constructing the system, and adjust our approach and design based on any problems we may encounter during that process. Another risk was brought up once we discussed our project with Professor Sankaranarayanan, who discussed certain difficulties in creating a painting robot. Specifically, he mentioned the main three things to consider would be the clustering algorithm, the color intensity, and the brush width. He gave us some advice in dealing with each issue, and we discussed the potential approaches and solutions amongst our team. Due to the difficulty in some of the image processing considerations, there are risks in how successfully we can translate a digital image to painting. We decided to keep our initial approach, which is based around the mean shift segmentation algorithm. However, if this fails, we can use any of several other clustering algorithms, with k-means being a viable backup. Regarding color intensity and brush width, there are several alterations we could potentially make to our painting procedure if either of these are an issue. We could modify our approach to only deal with silhouettes, only use edge detection and paint the edges of the input image, or just reduce the detail we recreate in our painting. Our painting head is designed so that it can hold pencils, paintbrushes, etc.

No significant changes were made to the existing design of the system, although we did finalize decisions on the hardware component of our project as well as how to power the robot. No changes have occurred to our planned schedule, as we are all on track with our progress.

This week I focused on ordering parts, creating and finding CAD files for use in the frame, and finalizing the design for the frame. We were able to order a majority of the parts we need this week, and hopefully they will arrive soon so that we can begin shifting to the assembly and early programming. Many were ordered through Amazon so this should be the case with 2-day shipping. I also continued modifying some of the Ultimaker files and found more to use which are compatible with the ordered parts, including some to house the bearings externally on the support frame. The design of the support frame has also been finalized and the parts are ready to be ordered, although the order has not been placed yet. The frame will be constructed primarily out of T-slotted aluminum which allows for easy connections and adjustments should they be necessary down the line. After ordering the parts our power needs were also clear and I worked on resolving how the entire gantry and pi setup would be powered. Additionally I have begun working on putting all of the parts into an assembly for easy viewing and modifying.

Overall this week I was on schedule. In addition to what is listed above we all worked on creating the slides for the design review and met with Professor Sankaranarayanan. Next week I will complete the assembly of all the parts and begin basic assembly and 3d printing once the parts arrive.

The most significant risks that could jeopardize our project is the failure to successfully create the 2D axis gantry system. The three of us are confident in our ability to write a working software algorithm with our experience, but we all lack any significant experience in robotics or mechanical engineering. As a result, we are frontloading the work for the physical aspect of our project, which includes assembling the actual robot as well as getting the hardware component functioning properly.  Right now, we are considering several alternatives for procuring the parts necessary for the creation of our gantry system, which is inspired by the gantry system used in Ultimaker 3D printers. Our current plan is to use CAD files that we found online of the Ultimaker gantry parts, such as screws and pulleys, and then customize them to our project specifications and 3D print them. In this approach, we would purchase more generic parts, such as rods and belts, from any source we want that would fit with our modified parts. The risks with this approach are possible structural weaknesses from using the 3D printer filament, possible inaccuracies from 3D printing small parts, and also the danger of parts not fitting together after our customizations. To mitigate these risks, we will test 3D printed parts for their sturdiness and how accurately the smaller details of a part are printed. We will also limit the amount of modifications we make to the parts to reduce the risk of breaking the system. We have several backup plans for obtaining the parts in the situation that our primary plan fails. One alternative is ordering official Ultimaker replacement parts to assemble our gantry system with. However, this approach would limit the customization available to us. On the other hand, it is almost a guarantee that the parts would work and fit together, due to being official replacements. A third possibility is ordering the parts online, but not necessarily all from a single source. We are thinking of using some of the more detailed Ultimaker replacement parts, such as pulleys and sliding blocks, but purchasing more generic components such as belts and rods from other sources. This would allow us to find belts or rods of our desired length, while giving us some freedom to customize. A drawback of this is that it is somewhat difficult to find some parts with certain specifications – for example, finding rods of a 8mm diameter that would fit with the Ultimaker parts.

We did not previously lock down many specifics for our design, so nothing significant has changed from our vision for the project and the requirements we detailed in our proposal. However, we are beginning to finalize decisions for the parts we plan to use as well as the specifications for our system, and how all the parts will fit together.

Below is our updated schedule:

This week I was primarily working on finalizing our design for our 2d gantry system and beginning to look for parts to begin construction. To begin this process we looked towards existing 3d printer designs, and found a page that documented several of the most basic and popular designs in 3d printers. All of the products used belts rather than threaded rods, as they seemed to operate faster and be easier to use with a stepper motor. Based on this we’ve decided to utilize a design with belts, and more specifically to follow the design of the Ultimaker models, as shown in the image below.

A major benefit of this design is that Ultimaker is an open source company, and all of the CAD files for the requisite parts are available online. After deciding on this design and finding exact measures of all of the parts I spent some time looking at what parts are available online. There was some trouble here as many of the official Ultimaker parts are sold with a huge markup and are not sold in the US, meaning shipping times and costs would eat away at our project. To circumvent this we have decided to modify the CAD files available to work with more generic parts which would be easy to obtain, and also allow us to customize the design to the needs of our project. We tried printing one of the modified parts to test for strength and print quality, which is pictured below.

The pulley pictured above is meant to have a rod through the center and to have a belt around the teeth. Based on this initial print, it seems that the 3d printed parts are durable and accurate enough to work in the final project.

I also began trying to design the frame and support of the gantry system, but have not finalized any decisions regarding that. Overall this week I was on schedule, as I was able to finalize how our gantry would work, found retailors to purchase generic copies, and tested 3d printing and began modifications. Mostly what I will be focusing on this upcoming week is finalizing those plans and ordering the basic parts associated with the Ultimaker design. Additionally I will make the modifications needed to the CAD files we have found and 3d print a majority of the initial parts we will need.