Agenda Meeting Purpose Detailed design review of P10543 Update of color measurement system. The objective of this technical review is to conduct an evaluation of the proposed design solution and to identify potential risks in the design and bill of materials. Meeting Date: February 12, 2010 Meeting Location: Building 78 Room 2130 Meeting time: 8:00 10:00 AM Timeline: Meeting Timeline Start time Topic of Review Required Attendees 8:00 Project Background Dr. Wyble, Mr. Hanzlik 8:10 System Architecture Dr. Wyble, Mr. Hanzlik 8:15 Overall System Design Dr. Wyble, Mr. Hanzlik 8:40 Mechanical Design Dr. Wyble, Mr. Hanzlik 9:05 Electrical Design Dr. Wyble, Mr. Hanzlik 9:15 Software Design Dr. Wyble, Mr. Hanzlik 9:35 Bill of Materials and Risks Dr. Wyble, Mr. Hanzlik 9:45 Wrap-Up Discussion Dr. Wyble, Mr. Hanzlik KGCOE MSD Page 1 of 32
Table of Contents Primary Documentation One Page Project Overview 4 Existing System 5 Customer Needs 7 Engineering Specifications 8 Overall Selected Design 9 Mechanical Design 13 Electrical Design 18 Software Design 28 Bill of Materials 30 Risks/Risk Mitigation 31 Action Items 32 KGCOE MSD Page 2 of 32
Upgrade of Color Measurement Device Detailed Design Review Dale Turley Jason Herrling Sam Seibert Dave Wagner Project Manager Lead Engineer Mechanical System Engineer Electrical System Engineer P10543 Page 3 of 32
Project # Project Name Project Track Project Family Upgrade of Color P10543 Controls & Automation Measurement System Start Term Team Guide Project Sponsor Doc. Revision Winter 10 Edward Hanzlik Dr. David Wyble A Project Description Project Background: The goal of the project is to update an existing color measurement system consisting of, a light source, color detector, and test platform. The existing system is capable of detecting color through different angles of incidence and detection. These angles are manually controlled though a user control panel. The main objectives of the project are to add a third degree of freedom which will allow the test sample to pitch up and down. It is also desired to automate the system by interfacing with a PC. Furthermore, the sample measurement needs to be measured against a reference sample. Problem Statement: The purpose of this project is to design and build a color measurement system to be used to describe the color of surfaces, particularly surfaces which change color with light and observed angles. The existing system does not provide enough functionality. It is desired to be able to describe the target with three degrees of observation and to be able to compare the measurement to that of a reference standard using the same angles of measurement. Objectives/Scope: 1. Design a new test sample stand 2. Design control system for equipment 3. Design computer interface for user Deliverables: Functional color measurement system New Design, Drawings, Sketches Required documentation Expected Project Benefits: Reinforcing the imaging science program at RIT. System will be a great teaching tool. Will allow for accurate color data. Basis for future senior design projects. Core Team Members: Dale Turley Project Manager Jason Herrling Technical Lead Sam Seibert Mechanical System Engineer Dave Wagner Electrical System Engineer Strategy & Approach Each subsystem of the complete system has been researched in order to decide upon materials and components. This includes comparison of motors, motor drivers, microcontrollers, software interfaces, and holder designs. Assumptions & Constraints: 1. The size of the system is constrained to fit within the dimensions of the current platform. 2. Budget to be about $2500. Issues & Risks: Project Issues/Risks/Constraints Project Understanding and Digesting By Team o New project o Lack of imaging science knowledge Available Resources o Obtaining resources o Order parts/hardware o Lead time Controls Issues o Understanding current system configuration o Getting up to speed with motors and encoders P10543 Page 4 of 32
Existing System Figure 1 Existing Partially Functioning System The College of Imaging Science at RIT purchased a partially functioning color measurement system, shown above in Figure 1, to be used to take color data of any sample inserted into the device. A beam of light is shined on the sample and the light reflected off of the sample is measured by a detector which then translated what it sees into a color. Normally the light measurement is compared against a measurement from some kind of reference (usually pure white) surface. The device in its current state easily allows the sample being measured to be oriented anywhere about a vertical axis, it also allows for the light detector to orient anywhere about the same axis but at a further radius away. This allows for the sample to be measured for color at different angular orientations and also at different angles of incident light. The customer would like to add an additional degree of motion for the sample, allowing it to be pitched up and down and different angles. P10543 Page 5 of 32
The significance of being able to measure a sample surface in three different degrees of freedom is that some materials change color depending on the orientation at which it is observed and the angle at which light contacts the surface. An example of such a surface would be a pearlescent paint job on a car. Figure 2 below shows the different axes of rotation for the system. As shown the light source is fixed in space and shines a beam of light (approximately 3mm in diameter) onto the surface of the sample. The axis labeled 1 is the sample yaw axis; it allows the sample to be rotated about the vertical axis thus changing the orientation of the sample. The second axis, Axis 2, is the sample pitch axis, it allows the sample to be rotated up or down about a horizontal axis further changing the sample s orientation. Axis 3 in the diagram represents how the holder will switch between testing the sample and testing the reference, it is intended to symbolize some sort of movement to change the samples but not necessarily about the axis shown. The fourth axis is the detector yaw, the detector rotates about the same vertical axis that the sample does but at a greater radial distance, this allows for different angles or incident light to be measured. Figure 2 Rotational Axes Drawn by Lawrence Taplin, MCSL/RIT P10543 Page 6 of 32
Customer Needs Figure 3 below depicts all of the needs of the project. The needs are categorized into areas of Function, Reliability, Physical Constraints, and Safety. All of the needs specified by the customer are currently met by the proposed solution. Customer Need # Customer Weight (out of 5) Description Figure 3 Table of Customer Needs Comments/Status 1 5 Function Device takes color measurement data Met 2 5 Has three degrees of freedom (sample yaw, detector yaw, pitch) Met 3 5 Switch between sample and reference with same angular and lateral positions Met 4 5 Ability to measure detection and incident angles Met 5 4 Ability to import input position data Met 6 4 Switch between sample and open (direct) measurement Met 7 3 Automated with minimal user setup Met 8 5 Reliability High repeatablilty of positions Met 9 5 High accuracy of angualar movements Met 10 5 Configurable and robust Met 11 4 Relatively inexpensive Met 12 3 Easy to use user interface Met Physical Constraints 14 5 Fits within the physical contraints of current system Met 13 3 Test sample and reference are close to same size Met Safety 15 5 Safe to leave unattended Met P10543 Page 7 of 32
Engineering Specifications The above customer needs are translated into quantifiable and measurable specifications which are used to fully describe the projected capabilities of the system. These capabilities are used to determine the design of the system. A marginal and target value are given for each, where the target is the goal set for the design and the marginal value will be used to determine if the design is successful once it is built and tested. Engr. Spec. # Relative Importance Source Metrics Unit of Measure Figure 4 Table of Engineering Specifications Marginal Value 1 11% CN8, CN10 Repeatability Percent error 5 3 2 9% CN9 Accuracy Steps/Rev 200 400 3 8% CN8, CN9, CN10 Offset of part surface from rotational axis Millimeter 1 0.5 Technical Target 4 8% CN11 Cost Dollars 3000 2000 5 7% CN5, CN7 Importable data Yes/No Yes Yes 6 7% CN3, CN6 Selectable measurement target Yes/No Yes Yes 7 7% CN13 Change in sample/reference surface area (assume square) Centimeter 10 ± 2 10 8 7% CN2 Change in sample pitch Degrees ±70 ±180 9 7% CN2, CN4 Change in sample yaw Degrees 270 360 10 7% CN13 Change in sample/reference thickness Centimeter 2.5 5 11 6% CN14 Radius of sample holder Centimeter 28 17 12 6% CN2, CN4 Detector visibility cone Degrees 140 180 13 6% CN12 Usability Rating 8 10 14 5% CN1 Digital output of measurements Yes/No Yes Yes P10543 Page 8 of 32
Overall Selected Design Figure 5 Assembly Integrated with Current System Figure 5 shows the new sample and reference holder design with motors and gears mounted to the detector arm table. Sample is in the test position and the reference is in the standby position. The surface being tested is shown in red through the view hole in the frame. The sample and reference leafs are moved by the flip motors through worm gears. The pitch angle is controlled by the tilt motor thought a worm gear. P10543 Page 9 of 32
Figure 6 Inserting Sample and Reference The sample tile and the reference tile are inserted into the holder fixture as shown above and clamped in place by four (4) corner screws. It is anticipated that the reference tile will be semipermanent where as the sample will be changed out with every use. The two smaller motors are 12V DC gear motors, they are both connect to 20:1 worm gears which are attached to shafts to control the positions of the sample and reference tile surfaces. When either surface is brought flush against the frame it is in the test position. Whichever surface is not in the test position is rotated away from the frame and clear of the other sample, this is referred to as the standby position. Figure 7 below shows the sample (red) in the test position and the reference (white) in the standby position. P10543 Page 10 of 32
Front View Back View Figure 7 Test and Standby Positions A third DC spur gear motor is used to control the pitch angle of the assembly. This motor is attached to the shaft through a 100:1 worm gear. Figure 8 shows how the sample rotates up and down to acquire different measurement angle. Figure 8 Pitch Angle P10543 Page 11 of 32
Overall System Architecture - PC LabVIEW Program Coordinate List Detector Microcontroller Output Data Sample flipup motor Position Feedback Reference flip-up motor Position Feedback Stepper Motor (Tilt) Position Feedback DC Motor (Holder Yaw) Position Feedback DC Motor (Detector Yaw) Position Feedback Figure 9 System Architecture P10543 Page 12 of 32
Mechanical Design Figure 10 Mechanical Flowchart P10543 Page 13 of 32
The selected test stand design allows for the testing surface to be rotated in two degrees of freedom, yaw and pitch. The two axis of rotation intersect at the point where the light beam from the stationary light source hits the sample. The entire holder rotates in a yawing motion about a rotating table. The table is connected though an 80:1 gear down worm gear to a brushless DC motor. The motor is controlled by a microcontroller. The test sample rotates with a pitching motion induced by a stepper motor mounted to the holder frame. The stepper motor is connected to a motor controller and driver which communicate with the microcontroller. The holder allows for the switching between test sample and reference sample through two stepper motors. Both steppers are run simultaneously allowing for the sample to move into the testing position and the reference to move into the standby position, and vice versa. Motor Torque Analysis The selected design requires the installation of three (3) new DC motors to control the pitch of the assembly and the location of the sample and reference surfaces. The pitch (or tilt) motor system is sized to handle the torque applied from the mass of the assembly and the torque required to move the assembly with a certain angular acceleration. Table 3 below shows the torque analysis for the tilt motor. The motor of inertia for this analysis is taken for the worst case scenario of sample and reference orientation, which is where each are oriented 90degrees from the measuring plane as shown. Tilt System Motor Analysis Dynamic Requirements Motor Specs Inertial Force of Tilt System 3.0459 in-oz-s^2 Motor Stall Torque 277 in-oz Worm Gear down ratio 100 (ratio) Motor Speed 17 rpm Max Static Torque of Tilt System 147.62 in-oz Angular acceleration of gear motor 1.78 rad/s^2 Motor Requirments Max static torque 1.48 in-oz Inertial contribution to torque 0.00 in-oz Total 1.48 in-oz Motor Torque Factor of Safety 187.58 Static Calculations Shaft Torque 147.62 in-oz Gear Radius 1.5625 in Axial Worm Thrust 94.474 oz P10543 Page 14 of 32
Table 4 below shows the torque analysis for one of the flip motors which is a similar analysis to the one above but takes into account a different moment of inertia and different motor characteristics. Sample Flip System Motor Analysis Dynamic Requirements Motor Specs Inertia of Flip System Shaft 0.4481 in-oz-s^2 Motor Stall Torque 110 in-oz Worm Gear down ratio 20 (ratio) Motor Speed 360 rpm Max Static Torque of Flip System Shaft 24.124 in-oz Angular acceleration of gear motor 37.70 rad/s^2 Motor Requirments Max static torque 1.21 in-oz Inertial contribution to torque 0.042 in-oz Total 1.25 in-oz Motor Torque Factor of Safety 88.11 Static Calculations Shaft Torque 24.124 in-oz Gear Radius 0.625 in Axial Worm Thrust 38.598 oz Motor Torque: Reflected Load Inertia T m = T l N J r = J l N 2 Where: N = Gear Ratio T m = Torque of Motor, oz-in T l = Torque of Load, oz-in J l = Load Inertia, oz-in.-sec 2 J m = Drive Motor Inertia, oz-in.-sec 2 J r = Reflected Load inertia, oz-in.-sec 2 P10543 Page 15 of 32
Stress Analysis - The vertical support is analyzed for stress failure given the locations of the point forces below in Figure 11. Based on the material shear stress and yield stress, the maximum values at which the point forces can be and not permanently deform the part are listed in the table below. Figure 11 Applied Moments Material Properties: 6061-T6 Aluminum Shear Strength: 30,000 psi Yield Strength: 40,000 psi Force Vector Maximum Allowable Force 1 78 lbs 2 39 lbs 3 312 lbs P10543 Page 16 of 32
Tolerance Analysis - We are concerned with the distance between the surface of the test sample and the point at which the pitch axis and yaw axis intersect. There are four (4) dimensions that can affect how far off those two points are. From the engineering specifications the largest distance these points can differ is 0.040 inches. In addition the distance is also affected by the pitch angle and the yaw angle, both as a function of 1/cosine. Assuming that the maximum pitch and yaw angles observed is ±70 the distance follows the function below. x = 0.0016cos 2 θcos 2 cos 2 θ+cos 2 Where and θ = pitch angle = yaw angle Apply the worst case scenario where both angles are 70 then, x = 0.009674 inch es Since there are four stacks for this dimension divide by four thus, each of the four critical dimensions should hold a tolerance of: ±0.0024 P10543 Page 17 of 32
Electrical Design Block Diagram: Flip-up motors subsystem Figure 12 Flip-up motors block diagram P10543 Page 18 of 32
Schematic: Flip-up motors subsystem - Arduino Board Brush DC driver Motor Sensor Figure 13 Flip-up subsystem schematic P10543 Page 19 of 32
Block Diagram: Tilt motor subsystem - Figure 14 Tilt motor subsystem P10543 Page 20 of 32
Schematic: Tilt motor subsystem - DAQ Board Brush DC Driver Motor Encoder Figure 15 Tilt motor subsystem schematic P10543 Page 21 of 32
Block Diagram: Yaw motors subsystem - Figure 16 Yaw motors subsystem P10543 Page 22 of 32
Control Pack Motor KGCOE MSD Schematic: Yaw Motor Subsystem - DAQ Board Encoder Figure 17 Yaw motors subsystem schematic P10543 Page 23 of 32
SPDT Relay DAQ Board Relay Driver Chip SPST-NC Relay KGCOE MSD Schematic: Relay Driving Circuit - Figure 18 Relay driving circuit schematic P10543 Page 24 of 32
Final Schematic Figure 19 Final schematic P10543 Page 25 of 32
Safety Circuit - When the cable is removed, the switch shown on the left actuates and disconnects the 12V power supply. The red lanyard will be replaced with a rigid cable shorter in length than the power and instrument wiring. This cable will run from the termination block on the back of the instrument to the sample holder. In the event that the sample holder rotates past its designated operating range the cable will trigger the switch and remove the 12V power supply from all systems. Figure 20 Switch and Lanyard When the 12 volt supply is removed the relays on the yaw motors will return to ground state and the motor will stop. In addition, power will no longer be available for the sample flip and tilt motors until the cable is reset. No further motion will occur until power is restored. All motors will be individually fused for further safety. Figure 21 Termination Block P10543 Page 26 of 32
Figure 22 Location of Termination Block P10543 Page 27 of 32
Software Design The software will be primarily developed in LabView and read input positions based on an Excel spreadsheet. Once the spreadsheet is read the program will then interface with the various controllers to obtain readings for each of the specified data points. When all of the data has been collected the information is compiled into an output spreadsheet for the users use. Software Flowchart - Figure 23 Software Flowchart P10543 Page 28 of 32
Microcontroller Software Flowchart - Figure 24 Microcontroller Software Flowchart P10543 Page 29 of 32
Bill of Materials Figure 24 Bill of Materials P10543 Page 30 of 32
Risks/Risk Mitigation Figure 25 Risk assessment P10543 Page 31 of 32
Action Items MSD II Project Schedule Test Plan Documentation Update documentation on EDGE site Management Level Review P10543 Page 32 of 32