Paint Flow Control Project #5, Chapter 2

A review: UEI (UEI) and Vivid Inc (VividInc) are collaborating on a project to develop paint flow control systems for UEI to sell to clients in Asia and also to provide a painting system for Vivid for industrial painting of remote control units and panels for various customers at Vivid's Santa Clara facility. Thomas Nguyen of Vivid and I are working on a plan to design/develop the control system. I had designed and developed a controller board using a Microchip Inc, microcomputer chip (dsPIC33F) and reported about it in a previous post. However, UEI prefers to use a commercially available microcomputer module that I had used on our Silk Screen Project, the Digi International BL2600 (the BL2600). I like the BL2600 since it is plenty fast enough for many control applications and has plenty of Digital and Analog I/O, plus Digi's Dynamic C compiler is an easy to use real-time development system.

The Digi International BL2600

The Digi International BL2600 SBC.

I will use the BL2600 to measure the paint flow value from a flowmeter and to output analog current signals to an electric motor driving the paint pump. The BL2600 also includes an Ethernet port (seen on the top of the board facing the rear) which I will use to communicate with a PC. The PC will be programmed in National Instrument's LabWindow/CVI (LW/CVI) which I used on the Silk Screen Project and had used at LLNL for  the Smart Sampler Project, both of which I reported on in previous posts. My LW/CVI code will act as a setup and monitoring program to allow the operator to set the operating mode, set the paint flow set-point and to record and graph the commands from the BL2600 Fuzzy Logic code and the values of the resulting paint flow. And as with my other projects, I will program the BL2600 with my incarnation of a Fuzzy Logic algorithm. However, I will need to revisit the algorithm, tweaking the Fuzzy Logic rules to attempt to optimize the Look-Up-Table. I expect to use Octave and the Fuzzy Logic Toolkit as I did for the Silk Screen Project. And the software will be a considerable update from the previous Paint Flow Control Projects since we are switching from my controller board design to the Digi BL2600. Also, on the Silk Screen Project where I used the BL2600, my Fuzzy Logic code resided in the PC since the Silk Screen system was so terribly slow, requiring an hour for the ink to dry. In the Paint Flow Control Projects, the dynamics are considerably faster as we measure the paint flow immediately with the flow meter and consequently the system response must be in tenths of a second.

Below is a simple block diagram for the system showing that the BL2600 controls the pump motor thru the Motor Controller and the Flowmeter provides a feedback signal of the paint flow.

New Paint Flow Control System Block Diagram.

GanttProject
Before we can go ahead with the project, UEI and VividInc must approve my plan for the system development. Accordingly, I am working on a plan. First I wrote a very rough Requirements Doc, then made a rougher schedule using the free GanttProject program from SourceForge (GanttProject). GanttProject does everything I need and will produce Pert Charts if desired. I came up with only eleven tasks, guessing at the time and resources (me) that would be required, set the starting date at July 1 and GanttProject produced a Gantt Chart, the Resources Chart and also the Pert Chart. You can export the charts to a PDF file which I find very useful for showing the client the tasks and schedule. So I definitely recommend GanttProject. I just now noticed that I goofed in my project chart and have updated it. Below is the Gantt chart, hopefully all corrected now.

Updated Gantt Chart for our new Paint Flow Control Project from GanttProject.

My GanttProject file shows my overall estimated time and costs for the development. Also I put together a list of the system components on an OpenOffice (Open Office) spreadsheet. I am currently using either OpenOffice or LibreOffice (LibreOffice) for my text and spreadsheet files.

Enclosure
For most of the components, I selected parts from Mouser (Mouser). However, I need an enclosure for the BL2600 and not finding the exact size box I need, I checked with Bud Enclosures (Bud). They suggested a couple of boxes that might be appropriate but they weren't a perfect fit and besides that, I would need many cutouts on the sides of the boxes for cable entries. So I did a search and found Protocase (Protocase), a Canadian company that will make an enclosure to your design along with cutouts that you can design and special cutouts such as AC receptacle and DB9 and others. They will make small quantities. Before I designed the enclosure using Protocase's free software, I made a floor plan of the parts layout using DoubleCad (DoubleCad), another freebie design software package. See the layout below.

Enclosure Floor Designed with DoubleCad.

To accommodate the BL2600, a power supply, a Bodine 3984 Isolation Module, some barrier strips, the DB9 connector and a Shaffner AC receptacle, the floor plan turned out to be 13.5" x 10" and I figured that the box should be 2" tall. So I could go ahead with the Protocase design using the Protocase software and got an immediate quote of $270 for two boxes. That would save me a lot of work and I expect would produce a much higher quality result than I could do with my simple tools. Below is my box design. I chose an aluminum L-shaped enclosure and included cutouts for the DB9 and AC receptacles plus cutouts for cable access to the Ethernet connector and other I/O.

Enclosure Design Using Protocase Design Software.

After getting the quote from Protocase, I assembled the list of components into a spreadsheet along with my estimate from the GanttProject schedule.

Bodine Motor and Controller
The Component list includes a Bodine motor, the model 1087 parallel shaft gearmotor, a model 3912 control module plus a model 3984 Isolation module to allow 4-20 mA current from the BL2600 to set the Bodine motor speed. The Bodine 1087 Gearmotor worked well in the Silk Screen Project, so we chose it to drive the paint pump in this project. It's a 1/5 hp motor with torque of 185 lb-in and speed of 46, but of course the motor speed is variable using the model 3912 controller driven by the BL2600 SBC.

The Bodine Model 1087 GearMotor.

Flowmeter
Also I included a MacNaught MX06P-2TE positive displacement oval gear flow meter, suggested by Colin Willard of Instrumart (Instrumart). The MacNaught flow meter is a bit questionable since the paint may include some abrasive material. We will have to try it out and learn how well it will stand up to the paint's abrasiveness. Previously, Coriolis type flow meters have been used for the abrasive paint but they are several times as expensive as the gear-type flow meter. However, we wanted to try the gear-type flow meter since the paint is not expected to be highly abrasive. The MX06P-2TE includes an LCD screen showing the flow readout and is quite compact as shown below.

The MacNaught MX06P-2TE Positive Displacement Oval Gear Flow Meter.

The component estimate came to $11,000. I passed this estimate along to Thomas for his evaluation. Hopefully they will agree with my estimate and we can get a contract to proceed with the project. That will be the next Chapter.