Paint Flow Control Project, Chapter 3.17

With Paintings by Heide in the Background.

A little hitch in our Paint Flow Control Project: contrary to my suppositions, I don't yet have the go ahead. Vivid Inc. in Santa Clara and Universal Electronics Inc (UEI) in Santa Ana have to figure out how to split the cost of the development project, if they will fund it. I think they'll go ahead but I was remiss in not sending a proposal to Vivid and UEI. Now I have sent two proposals! My first proposal assumed that they would be building only two systems to start but John wanted to expand it to either seven or eleven systems. UEI has a facility in northern China for doing fabrication of their remote controls and UEI is planning on installing six or seven painting systems, each presumably with our paint flow controller. Also, John at Vivid needs one system for their work in Santa Clara. Anyhow, I revised my first proposal for one, seven and eleven systems. They will have to chew on it for a bit but I am fully expecting approval soon.

My last post way back on September 13 described the final tweaking of my Fuzzy Logic algorithm for controlling the paint flow. I think the simulations show an excellent response and accurate settling to the set-point and I expect the results in the real system will be equally good. So this post is finally not about Fuzzy Logic.

This post is describing a revision of the system design to a simpler and better system, I believe. It's the result of a lunch meeting that Thomas Nguyen and I had at an In-N-Out Burger cafe across from the San Jose Airport in Santa Jose. It's our favorite place to meet and discuss the project and also solve world problems. Anyhow, Thomas said we should replace the PC with a touch-screen LCD for Monitoring and Supervising of the paint flow control process. I had previously used a PC for that purpose and had figured on doing it again. However, it requires the operator to be computer savvy and seems unnecessarily complex, plus it takes up space and requires some maintenance. For that previous system I had used my old Dell Inspiron notebook PC and of course the users left it plugged in to power continuously, resulting in a dead battery.

Thomas' suggestion of using a touch-screen LCD for this incarnation of the paint flow control system switched on the proverbial light-bulb over my head. I immediately realized that Thomas had a great idea and agreed on the spot. When I got home I started researching to find touch-screen LCD's that I might be able to use. First I thought of WinSystems whose products I had used in the Smart Sampler project at LLNL that I described back in October 2014. I used the WinSystems LX800 and other boards including their PPC3 6.5" LCD panel, programming the LX800 in National Instruments LabWindows/CVI to make a GUI for the control and the graphical display of data. However, a paint flow control system built with WinSystems boards would be overly complex with several boards, more complex and more expensive than I wanted for the paint flow controller.

So I began looking for alternatives and found a Wikipedia listing of Single-Board-Computers (SBC Comparisons). However, I wanted to quickly find a suitable SBC and didn't want to spend days checking out each and every product listed in the Wikpedia article. Furthermore I was surprised that WinSystems wasn't even listed. So that would mean that besides checking out the multitude of companies and products in the Wikipedia article, I would have to search for additional products that Wikipedia didn't include. However, a few names stood out, notably Arduino, Raspberry Pi and Beaglebone, products normally thought of for education uses. However, I learned that the Beaglebone is often used in industrial control applications. Then searching some more for LCD's, I found 4DSystems (4dsystems), a manufacturer of touch-screen LCD's and at first concentrated on their LCD's for which they have design software, but I was leery of those proprietary products since I wasn't sure that I would be able to make a suitable GUI on their systems and using their software. Also I wanted an LCD that was at least 7" diagonally.

At this time I was still expecting to connect the LCD screen to the Digi International BL2600, the BL2600 to directly control the paint flow using my Fuzzy Logic algorithm. Perusing the 4DSystems products, I noticed that they have touchscreens that interface to Arduino, Raspberry Pi and Beaglebone Black micro boards. I was aware that a Linux operating system is available for the Raspberry Pi and the Beaglebone Black, so started researching those possibilities. Initially I was thinking of connecting one of the 4DSystems LCD touch-screens to the BL2600 but then it occurred to me that I might be able to eliminate the BL2600 and do all of the control and GUI on a single 4DSystems LCD widget. So I started thinking of which of the three micro board based 4DSystems I might be able to use. I figured that the Arduino wouldn't be fast enough for the job and studying the Raspberry Pi and the Beaglebone Black (BBB), I soon discovered the weakness of the Raspberry Pi for my application: it doesn't have an Analog-To-Digital Converter (ADC) for measuring the current from the paint flow-meter. However the BBB has an ADC for measuring the current from the flow-meter. For the output signals to drive the paint pump, I could use the Pulse-Width-Modulation (PWM) feature on the BBB to produce an analog voltage and/or current as I had done on my Microchip controller board that I described in a post on December 16, 2014. I would have to design and build a simple interface board or Cape as it is called for the Beaglebone. Piece of cake. And using Linux on the Beaglebone Black, I could make a GUI for Monitoring and Supervising the control system such as I had for the Fuzzy Logic simulations.

So now my plan is to use a Beaglebone Black as the paint flow controller and a 4DSystems 4DCAPE-70T for the GUI for Monitoring and Supervising the paint flow control process. I particularly like this idea since it is a simpler system, no PC is needed and no Ethernet communication is required. So the operator will not have to be computer savvy, assuming that I can make a GUI that is intuitive to operate. All the software is included in one system, making my software development simpler. I wrote up a short explanatory note for Vivid and UEI and also a new proposal for one system, seven systems or eleven systems. Thomas Nguyen likes the idea and hopefully John and UEI will also like it and will approve me to go ahead and develop the system.

Here are photos of the Beaglebone Black and the 4DSystems 4DCAPE-70T:

The Beaglebone Black

The 4DSystems 4DCAPE-70T.