Optical Tape Measure

1. Optical Tape Measure Abstract Technical Approach Inexpensive ultrasonic tape measures are available that can only measure perpendicular distances to fairly large, flat surfaces. Complex environments make it nearly impossible to determine which surface corresponds to the measured distance. Determining the distance between any two designated spots and producing a model of a measured object are impossible with current ultrasonic tape measures. The team is designing and implementing an optical replacement for the tape measure that will measure the distance to any visible spot within 100 feet of the device. • Operation Procedure • Step 1: User presses the button to initiate the sequence • Step 2: The counter and the transmitter are enabled simultaneously • Step 3: The transmitter sends out a very short laser pulse while the counter begins timing • Step 4: The receiver detects the reflected pulse and stops the counter • Step 5: The controller computes the distance from the data received from the counter • Step 6: The controller outputs the distance to a LCD • Other Technologies Considered • Calculate the distance using multiple point locations and trigonometric angles • Measuring the phase relationship between the transmitted and received signals • Measuring the laser intensity at the object point and calculate the distance Introduction Power supply Transmitter button • Problem Statement • Current ultrasonic tape measures are available that will measure perpendicular distances up to fifty feet from the device. Pointing these devices to particular objects can become impossible in complex environments. A tape measure is needed that will measure the distance to any visible spot within its range. • Operating Environment • Shall be used both inside and outside • Shall be exposed to rain, sleet, and snow • Shall be used in dusty locations • Intended Users • Traditional tape measure users • Construction workers • Surveyors • Intended Uses • General measurements • Recreational sports • Surveying • Assumptions • Object points to be measured are stationary • Users will have previous experience with traditional tape measures • Small batteries will provide enough power for device operations • Limitations • Device shall measure distances up to 100 feet in length • Accuracy shall be within ± 0.5% • Shall be smaller than 6”x 8” x 3” and weigh less than 1 lb Start LCD Controller Counter Stop Receiver Expected End-Product and Deliverables • A small, durable, lightweight optical tape measure • A user’s manual that will explain to the user how to operate the device • A maintenance manual that will explain to the user how to properly care for the device • The test results obtained during the testing of the prototype Testing Approach The prototype will be tested and debugged to make sure all parts of the system are being controlled properly. The laser device will initially be tested in low light environments. The device’s measurements will be recorded and checked for accuracy at multiple distances from a known object. Later tests will be done under abnormal environmental conditions. These tests will check the device’s accuracy under several different weather conditions. Accuracy will be recorded for each condition and checked against the accuracy of the ideal test. Design Requirements Resources • Design Objectives • Simple one button operation • Measures the distance from the back end of the device to an object point • Shall be easy to aim in order to determine what the object point is • Functional Requirements • Shall be able to measure distances up to 100 feet with ± 0.5% accuracy • Shall calculate the distance from the device to an object point • The calculated distance shall be displayed to a LCD for the user • Design Constraints • The tape measure shall be small enough to fit in the palm of a user’s hand • The completed project shall cost less than $215 • Shall be easier to use than a traditional tape measure • Milestones • Project Definition • Researching and designing an optical tape measure • Implementation of a prototype of the final design to be used in testing • Testing of the design prototype for accuracy and distance • Documentation of the project results Financial Resources Total Cost: $215 Personnel Effort Total Hours: 417 Closing Summary As the world advances and technologies become smaller and faster the old way of accomplishing simple tasks has become obsolete. Not that long ago everyone used the traditional tape measure to which we are all accustomed. Now, however, there are several more options available to someone wanting to make a measurement. Ultrasonic devices have been created that can capture distances at the push of a button, but these devices also have drawbacks. Ultrasonic devices are difficult to aim and are only accurate up to 50 feet. Thus, this project will use optical technologies to create a device that will both increase the measurement range and make aiming easier for the user. Schedule Project Team Information May 04-30 Team Members Nick Freese Jason Thompson Bruce Fu Eugene Zimmer Faculty Advisors Degang Chen Aleksandar Dogandzic Client Senior Design