8 TDK Tronics has developed a singleaxis accelerometer with an industrial temperature range for uncrewed systems, writes Nick Flaherty. The AXO314 builds on the previous 315 for avionics, but with a range of -40 C to 85 C, rather than -55 C to 105 C, opening up more applications, said Pierre Gazull, product marketing manager at TDK. “This is aimed at new kinds of applications for us, such as the surveying and mapping equipment market, as that can be done in the air, under the sea or on the ground with more relaxed requirements compared to pure avionics. The more accurate the positioning is on the vehicle, the more accurate you will get on the final survey data,” he explained. The accelerometer uses an interdigitated capacitive structure to measure up to +/- 14 g with a composite bias repeatability of 1 mg. It features a 24-bit SPI digital output enabled by a high-precision, sigma-delta, low noise, analogue-to-digital converter (ADC). It is hermetically sealed in a 28-pin ceramic, surface-mount, J-lead package. “Our sensors are shipped factorycalibrated individually. The end-customers can overwrite this and apply their own calibration profiles using free memory slots. For example, to be very precise on a smaller temperature range of -10 C to 20 C for subsea designs and get the full performance,” Gazull said. “Typically, our customers have 3D integration with a combination of six sensors, three accelerometers and three gyros. As we provide tactical-grade devices for autonomous vehicles, they take special care on the way the sensors are mounted to guarantee maximum performance at system level after assembly. They put different sensors on the PCBs and calibrate the system. “You use one gyro to measure the rotation around the axis and one accelerator to sense movement, so you need three gyros and three accelerometers to get the 3D motion sensing of the full system. For some applications there may be a hybrid where people need one very precise axis with the others more relaxed, such as land vehicles where heading accuracy is critical.” The AXO314 has the same SPI serial interface as the other devices in the family to make integration quicker and easier. “If engineers are using accelerometers and gyros from Tronics, and they know how to communicate with the accelerometer, they know how to communicate with the gyros. The common interface is more efficient than having heterogeneous sensors with hybrid communication interfaces, which will increase the cost and complexity of the electronics,” Gazull added. Accelerometers Platform one xx October/November 2024 | Uncrewed Systems Technology Bringing the temperature down A single-axis accelerometer (Image courtesy of TDK Tronics) Researchers in Switzerland have developed a combined AI and radar technology for UAVs monitoring invasive plants, writes Nick Flaherty. The system monitors invasive alien plants (invasive neophytes) that are difficult to detect and tackle. Invasive species like Japanese knotweed, which can replace native plants, or narrowleaved ragwort, which is poisonous, are becoming increasingly common. They can damage agriculture, and infrastructure such as train tracks and signals. The AI is trained to read high-resolution images taken by a UAV, identify which fields are covered in invasive alien species and mark them in blue. Sensors A consortium of research lab CSEM, the University of Zurich and the Zurich University of Applied Sciences ZHAW, as well as Swiss Federal Railways (SBB) and ExoLabs, is taking a new approach to monitoring these species from the air. AI is already capable of detecting certain plants or animals in highresolution images, but these are aerial photos taken from great height, where small neophytes are just a few pixels in size, making it difficult to tell them apart from native plants. Vegetation ecologists, and data and sensor specialists are working together on the neophyte radar. AI/radar combo checks plants Detecting invasive plant species via UAV (Image courtesy of CSEM)
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