Unmanned Systems Technology 010 | nuTonomy driverless taxi | Embedded computing | HFE International marine powertrain | Space vehicles | Performance monitoring | Commercial UAV Show Asia report

72 Focus | Performance monitoring They traditionally come with three- wire voltage or two-wire current square wave output signal interfaces, and generally use adaptive threshold sensing schemes to improve sensor performance and reduce the sensitivity of the sensor mounting location relative to the target. Engine knock vibration can be monitored with a piezoelectric sensor that generates current from the movement of components in the engine. Commonly mounted on an engine block or cylinder head, it produces an output voltage in proportion to the engine vibrations caused by knock, which occurs in an engine when the air-fuel mixture is not ignited correctly. When knock is present on the sensor signal, the engine control module (ECM) controls it by retarding the spark timing in a petrol engine, or the injection timing in a diesel engine. When it comes to temperature, monitoring, both fluid and air are important. Fluid temperature sensors are continuous function devices that change resistance inversely with temperature. They measure the temperature of oil, fuel, water or engine coolant and provide a signal to the powertrain control module. Air temperature sensors work in the same way, and measure engine intake air temperature in the manifold, intake air duct and air cleaner. Conclusion Sensors are more essential to complex autonomous systems than ever. In critical environments, the safety and security of successful operations rely on vital inputs that are derived from highly accurate and reliable sensing technologies. Being able to monitor the performance of a system and predict problems before they occur is a key element of the use case of autonomous vehicles. It allows them to be operated with lower maintenance costs and higher availability, as replacements can be sent out automatically. All of this depends on sensors and performance monitoring. Acknowledgements The author would like to thank Neville Meech at Reventec, Ben Miller at Draganfly, Ladd Howell at Flow Technology, Paul Hock at Max Machinery and John Norris at Yuneec UK for their help with researching this article. October/November 2016 | Unmanned Systems Technology GERMANY Bosch Sensortec +49 7121 35 35900 www.bosch-sensortec.com Sensitec +49 6441 97880 www.sensitec.com JAPAN Renesas/Intersil - www.intersil.com THE NETHERLANDS NXP/Freescale - www.nxp.com Xsens +31 88 97367 00 www.xsens.com SWITZERLAND Colibrys +41 58 100 5000 www.colibrys.com STMicroelectronics +41 22 929 29 29 www.st.com UK Reventec +44 1725 510321 www.reventec.com Sentronics +44 1725 513703 www.sentronics.com USA Analog Devices +1 781 329 4700 www.analog.com Flow Technology +1 480 240 3400 www.ftimeters.com Maxim Integrated Products +1 408 601 1000 www.maximintegrated.com Max Machinery +1 707 433 2662 www.maxmachinery.com MEMSIC +1 978 738 0900 www.memsic.com Some examples of performance monitoring technology suppliers