Semiconductor Robot
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Trinity University Digital Commons @ Trinity Engineering Senior Design Reports Engineering Science Department 4-17-2008 Semiconductor Robot Jude Ankrah Trinity University Marton Gergley Trinity University Mike Gonzalez Trinity University Charles Jarvis Trinity University Sean C. Kienle Trinity University Follow this and additional works at: https://digitalcommons.trinity.edu/engine_designreports Repository Citation Ankrah, Jude; Gergley, Marton; Gonzalez, Mike; Jarvis, Charles; and Kienle, Sean C., "Semiconductor Robot" (2008). Engineering Senior Design Reports. 13. https://digitalcommons.trinity.edu/engine_designreports/13 This Restricted Campus Only is brought to you for free and open access by the Engineering Science Department at Digital Commons @ Trinity. It has been accepted for inclusion in Engineering Senior Design Reports by an authorized administrator of Digital Commons @ Trinity. For more information, please contact [email protected]. TRINITY UNIVERSITY Final Design Report Semiconductor Robot Jude Ankrah Marton Gergley Mike Gonzalez Charles Jarvis Sean Kienle Advisor: Michael Yockey 4/17/2008 A large line-following robot was built to transport semiconductor wafers in semiconductor factories. The criteria for a successful robot were decided upon prior to designing. The robot was designed using both mechanical and electrical engineering techniques to ensure that the final design met the outlined criteria. Each electrical subsystem was tested successfully prior to being installed on the robot. However once all the components were installed the robot was not able to move autonomously because the DC motors selected could not provide adequate torque. For future robot designs it is imperative that the motors be tested thoroughly because there is a substantial difference between specifications and actual performance. 1 Executive Summary The task was to design and construct a robot to work in a semiconductor fabrication plant that could transport semiconductor wafer cassettes between stages in the fabrication process. The motivation was to provide a way for older fabrication plants to be competitive with new fabrication plants that feature overhead systems for transporting wafer cassettes. In order for the robot to improve efficiency it needed to perform better than the current system in which the plant operators carry the cassettes to the next stage in the process. This meant that the robot had to move and navigate faster than an average person walking. The robot must not emit particles since it would be operating in a clean-room environment and it must be tall enough that the average worker could unload and load the cassette with minimal bending. The robot must also be able to protect the semiconductor wafers both during transport and in the event of a collision and it must be able to operate within the factory without hindering the flow of traffic in the factory which means it should not take up more room than is necessary. A large line-following robot was designed to meet these constraints. A line following robot was selected because it is simple and nondestructive to install paths within the factory. The robot uses omni-directional wheels to allow the robot to translate instead of turning and an array of infrared sensors mounted on the bottom ensure that the robot stays on the line. The robot can operate autonomously by using an onboard computer that tells it to follow preprogrammed paths and only requires the operator to load or unload the cassette and then enter the next destination. The mechanical components of the design (the frame, cassette holder, electronic housing, and wheel assemblies) were constructed without testing. All of the electrical components were tested prior to installation to ensure that they would work once installed and to attempt to decrease the amount of time spent debugging. Once the electronics were working properly, they were mounted onto the frame along with the battery. The test of the robot as a whole was not successful since the motors that were purchased were not capable of providing enough torques to move the robot. This problem arose because the torque specifications listed on the website were nearly double the measured torque. Given this knowledge regarding the difference between motor specifications and their actual performance, it is recommended that a replacement motor is used that can provide adequate torque by means of either a higher gear ratio or a more powerful motor. The robot successfully met the height requirement, the clean-room compatibility requirement, the size requirement and the wafer protection requirement. It did not meet the requirements that governed the robot in motion. ~ 1 ~ 2 Table of Contents 1 Executive Summary -------------------------------------------------------------------------------------------------------- 1 2 Table of Contents -------------------------------------------------------------------------------------------------------- 2 3 Table of Figures -------------------------------------------------------------------------------------------------------- 4 4 Table of Tables -------------------------------------------------------------------------------------------------------- 4 5 Problem Statement -------------------------------------------------------------------------------------------------------- 5 5.1 Constraints -------------------------------------------------------------------------------------------------------- 5 5.2 Working Criteria -------------------------------------------------------------------------------------------------------- 8 6 Final Design -------------------------------------------------------------------------------------------------------------------- 11 6.1 Social Design Constraints -------------------------------------------------------------------------------------------- 11 6.2 Mechanical Design -------------------------------------------------------------------------------------------- 12 6.2.1 Materials Used -------------------------------------------------------------------------------------------- 13 6.2.2 Motors -------------------------------------------------------------------------------------------------------- 15 6.2.3 Wheels -------------------------------------------------------------------------------------------------------- 16 6.2.4 Holder -------------------------------------------------------------------------------------------------------- 17 6.3 Electrical Design -------------------------------------------------------------------------------------------------------- 18 6.3.1 Input -------------------------------------------------------------------------------------------------------- 18 6.3.1.1 Infrared Pairs -------------------------------------------------------------------------------- 18 6.3.1.2 Sonar Rangefinders -------------------------------------------------------------------- 19 6.3.1.3 Key Pad -------------------------------------------------------------------------------------------- 20 6.3.2 Controller -------------------------------------------------------------------------------------------- 20 6.3.2.1 Peripheral Interface -------------------------------------------------------------------- 21 6.3.2.2 Logic -------------------------------------------------------------------------------------------- 22 6.3.3 Output -------------------------------------------------------------------------------------------------------- 23 6.3.4 Power Source -------------------------------------------------------------------------------------------- 24 6.3.5 Warning System -------------------------------------------------------------------------------------------- 24 ~ 2 ~ 7 Testing -------------------------------------------------------------------------------------------------------------------- 25 7.1 Battery -------------------------------------------------------------------------------------------------------------------- 25 7.2 Input/Output -------------------------------------------------------------------------------------------------------- 26 7.2.1 GPIO -------------------------------------------------------------------------------------------------------- 26 7.2.1.1 Speed and Functionality -------------------------------------------------------------------- 27 7.2.1.2 Infrared Sensors -------------------------------------------------------------------------------- 28 7.2.2 I2C -------------------------------------------------------------------------------------------------------- 29 7.2.2.1 Sonar Sensors -------------------------------------------------------------------------------- 29 7.2.2.2 Motor Drivers -------------------------------------------------------------------------------- 31 7.3 Full Scale Testing -------------------------------------------------------------------------------------------------------- 31 8 Conclusions -------------------------------------------------------------------------------------------------------------------- 32 9 Recommendations -------------------------------------------------------------------------------------------------------- 38 10 Bibliography -------------------------------------------------------------------------------------------------------------------- 40 A Mechanical Drawings -------------------------------------------------------------------------------------------------------- A-1 B Circuits Diagrams and Code -------------------------------------------------------------------------------------------- B-1 C Bill of Materials 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