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Wireless TPS Sensors Chris Johnson Jesse Pentzer Brandy Holmes John Sochacki Lucus Wells Outline Background Needs/Specs Designs Design 1 Design 2 Design 3 Trade Study Sensors Budget Schedule Challenges Conclusion Acknowledgments Slide #2 Background Slide #3 The re-entry environment is extremely difficult to model. NASA Ames desires a wireless sensor system that can be integrated into the Thermal Protection System (TPS) of entry vehicles. Complications with adding extra wiring and the risk involved in adding sensors to the mission. A wireless sensor system would remove wiring complexities, reduce mass, and reduce risk associated with cable cutting. With a greater understanding of the environment encountered during atmospheric re-entry the TPS of future missions could be made safer and more efficient. Needs/Specifications Need Specification Slide #4 Target Value Unit Multi-Nodal Wireless Architecture 1) Number of Nodes Architecture can Support 10 Multiple Sensors per Node 2) Number of Sensors per Node 5 Multiple Sensor Types per Node 3) Minimum Number of Different Sensors Per Node >= 2 Integration with Rise Balloon 4) Maximum Size 4 x 5 x 0.5 inches 5) Maximum Weight 16 ounces 6) Sensor Pressure 0 to 14 psi 7) Minimum Sensor Temperature -60 °C 8) Maximum Sensor Temperature 1000 °C 9) Wireless Signal Range 10 meters 10) A to D Resolution 10 bits 11) Maximum Electronics Temperature 125 °C X-Jet Testing Design One Sensor Slide #5 Design #1 & #3 Wire Sensor Node Sensor Node 1 Sensor Wire Thermocouples Sensor Signal Flow RF Wireless Link Wire Sensor Node 2 Sensor Wire RTD Network Analog Analog Pressure Sensor Wire Cold Junction Correction Chip Amplification UART Receiver Analog PIC Micro- UART Buffer processor UART XBee Wireless I2C Sensor Receive Node RF Wireless Link Wire Wire Sensor Sensor Node 3 Sensor Wire Wire Sensor RF Wireless Link Power Flow Sensor Li Ion 7.4V Battery 7.4V Battery Protection Circuit 5V LDO Regulator 5V PIC Microprocessor 5V RTD Network 5V LDO Regulator 5V Buffer 5V Pressure Sensor 5V LDO Regulator 5V 3.3V LDO Regulator 3.3V 7.4V Cold Junction Correction Chip XBee 5V Amplification Design One Slide #6 Design #1, #2, & #3 Receiving Node Transmitter Power Flow Signal Flow XBee Pro Reciever Li Ion 7.4V Battery Battery Protection Circuitry Rabbit Microprocessor Data Acquisition 3.3V LDO Voltage Regulator XBee 3.3V LDO Voltage Regulator Rabbit Microprocessor Design Two Sensor Slide #7 Design #1, #2, & #3 Wire Receiving Node Sensor Node 1 Wire Sensor Wire Sensor Node 2 Sensor Wire Wire Wire Sensor Sensor Node 3 Sensor Wire Wire Sensor Rabbit Microprocessor Data Acquisition Transmit Node Wire Wire XBee Pro Reciever RF Wireless Link Sensor Sensor Transmitter Receive Node Signal Flow Wire Wire Power Flow Sensor Li Ion 7.4V Battery Battery Protection Circuitry 3.3V LDO Voltage Regulator XBee 3.3V LDO Voltage Regulator Rabbit Microprocessor Design Two Slide #8 Design #2 & #3 Design #2 & #3 Sensor Node Transmit Node Analog Power Flow Pressure Sensor Li Ion 7.4V Battery Cold Junction Correction Chip Amplification UART Sensor Node Transmit Node Analog PIC Microprocessor Signal Flow RTD Network Analog UART Receiver UART UART or I2C UART Rabbit Microcontroller UART I2C 7.4V Battery Protection Circuit 7.4V 5V LDO Regulator 5V PIC Microprocessor 5V RTD Network 5V LDO Regulator 5V Buffer 5V Pressure Sensor 5V LDO Regulator 5V Cold Junction Correction Chip 5V Amplification Power Flow Signal Flow Thermocouples Li Ion 7.4V Battery 7.4V Battery Protection Circuit 7.4V 5V LDO Regulator 5V 3.3V LDO Regulator 3.3V XBee 5V LDO Regulator 5V Rabbit Microcontroller UART of I2C XBee Wireless Design Three Sensor Slide #9 Design #1, #2, & #3 Wire Receiving Node Sensor Node 1 Sensor Wire Wire Receive Node Wire Sensor Node 2 Sensor Wire Wire Data Acquisition RF Wireless Link Transmit Node Wire Wire Wire Sensor Sensor Power Flow Sensor Node 3 Sensor Rabbit Microprocessor RF Wireless Link Sensor Sensor XBee Pro Reciever Signal Flow Sensor Transmitter Wire Wire Sensor Node Wire Sensor Sensor Sensor Li Ion 7.4V Battery Battery Protection Circuitry 3.3V LDO Voltage Regulator XBee 3.3V LDO Voltage Regulator Rabbit Microprocessor Design Three Slide #10 Design #1 & #3 Design #2 & #3 Sensor Node Analog Power Flow Pressure Sensor Li Ion 7.4V Battery Cold Junction Correction Chip Amplification Thermocouples UART Analog PIC Micro- UART processor Buffer UART XBee Wireless 7.4V RTD Network Analog Pressure Sensor I2C Battery Protection Circuit Analog Cold Junction Correction Chip UART Amplification Analog Transmit Node Receiver Signal Flow RTD Network Analog 5V LDO Regulator 5V PIC Microprocessor 5V RTD Network 5V LDO Regulator 5V Buffer 5V Pressure Sensor 7.4V 5V LDO Regulator 5V 3.3V LDO Regulator 3.3V Cold Junction Correction Chip XBee 5V Amplification Power Flow Signal Flow Thermocouples Sensor Node Li Ion 7.4V Battery PIC Microprocessor UART I2C 7.4V Battery Protection Circuit 7.4V 5V LDO Regulator 5V PIC Microprocessor 5V RTD Network 5V LDO Regulator 5V Buffer 5V Pressure Sensor 5V LDO Regulator 5V Cold Junction Correction Chip 5V Amplification Design Three Slide #11 Design #2 & #3 Transmit Node Power Flow Signal Flow Sensor Node Receiver UART Li Ion 7.4V Battery 7.4V Battery Protection Circuit UART or I2C 7.4V UART Rabbit Microcontroller 5V LDO Regulator 5V 3.3V LDO Regulator 3.3V 5V LDO Regulator 5V UART UART of I2C XBee Rabbit Microcontroller XBee Wireless Trade Study Slide #12 Value of Designs (1-3) Item Design 1 Design 2 Design 3 Comments Low Cost 1 3 2 all will meet budget Small Size 3 1 2 node size minimized Low Weight 3 1 2 low impact on VAST balloon Low Software Complexity 2 3 1 Low Hardware Complexity 3 1 2 Low Power Consumption 1 3 2 Meets additional Priorities 2 3 1 priorities besides #1's Low Packaging Complexity 3 2 1 protective packaging only High Usability 2 1 3 includes versatility Feasibility 3 2 1 Summation 23 20 17 This total would suggest that the completely wireless option has the most benefits Sensors Omega Type K Thermocouples with Glass Braid Insulation Range: -270 to 1372 °C Uncertainty: Greater of 2.2 °C or 0.75% Cost: $33 for five thermocouples with one meter leads Honeywell ASDX-DO Series Pressure Sensors Range: 0 to 30 psi absolute Uncertainty: 2.0% Full Scale Temperature Range: -20 to 105 °C Cost: $33.27 Each Omega Thin Film Resistance Thermal Detectors Range: -70 to 500 °C Uncertainty: Dependent on Calibration Equation Cost: $47.50 for pack of five Slide #13 Budget • • Common Cost to all designs: $679.16 Design One • • • 9 PCB’s 9 Batteries 9 X-Bee chips • • Design Two • • • 11 PCB’s 3 Batteries 3 X-Bee’s • • Total Cost: $1137.41 Design Three • • • 11 PCB’s 5 Batteries 5 X-Bee’s • • Total Cost: $1333.91 Total Cost: $1222.91 Thermal Exposure’s Budget: $2240 Slide #14 Schedule Slide #15 Challenges Slide #16 Code Complexity RF Opaque Materials Design Packaging for Harsh Landing Conditions Thermal Protection of Circuit Conclusions Thermal Exposure’s Favorite? Design One!!! Why? Versatility Simplicity of Code Simplicity of Design Small Size and Weight Slide #17 Acknowledgments Faculty Advisors David Atkinson Steve Beyerlein Mentors Greg Swanson Tye Reid Justin Schlee NASA Ames David Hash Johnny Fu Ed Martinez Slide #18 Slide #19 Questions?