What A Sensor Sees
A drone carrying takeout takes off from a suburban restaurant to a downtown office building ten miles away moving at a speed of 40 MPH. As other drones cross the busy city airways, our delivery drone elevates smoothly to avoid oncoming air traffic. Within ten minutes, the office worker who placed the order is enjoying a hot, fresh lunch.
Sound like a fantasy? The reality is approaching sooner than you think. Drone technology is becoming more and more intelligent, enabling drones to achieve accurate hovering and maneuvering around air and land obstacles. With the advancement of drone technology, TE Connectivity (TE) plays a critical role in the drone application solution.
TE’s digital barometric pressure sensor (MS5607/MS5611) measures air pressure then converts it into altitude. The sensor identifies air pressure of 0.012mbar (1.2pa and is approximately equal to lifting height of 10cm) at a low altitude, near sea level. Drones utilize air pressure sensors to stabilize altitude, allowing hover capabilities needed for videography or photography. Combined with the accelerometer and gyroscope, barometric pressure sensors enable drones to fly with precision.
Equipped with SPI and I2C bus interface, the barometric pressure sensor is optimized for altimeters and barometers with an altitude resolution of 10cm/20cm. The sensor module includes a high linearity pressure sensor and an ultra-low power 24 bit ΔΣADC with internal factory calibrated coefficients. It provides a precise digital 24 Bit pressure and temperature value with different operation modes that allow the user to optimize for conversion speed and current consumption. A high resolution temperature output allows the implementation of an altimeter/thermometer function without any additional sensor.
The MS5611-01BA/MS5607-02BA can interface with virtually any microcontroller. The communication protocol is simple, without the need to program internal registers in a device. Small dimensions allow for integration in mobile devices. This new sensor module generation is based on leading MEMS technology. The sensing principle allows for very low hysteresis and high stability of both the pressure and temperature signal.
TE’s new digital humidity sensor with temperature output (HTU21D(F) accurately measures temperature and humidity (measurement scope is 0~100%RH with 2%~3% accuracy). The temperature measurement scope is -40~120C, the accuracy is +/-0.3C between 0~60C. Setting new standards in terms of size and intelligence, HTU21D(F) is embedded in a reflow solderable Dual Flat No leads (DFN) package with a small 3 x 3 x 0.9 mm footprint. This sensor provides calibrated, linearized signals in digital, I²C format.
Agricultural spraying application requires even distribution across the entire field to eliminate the targeted insects while avoiding over-spraying crops. Atmospheric data is critical for maintaining the consistent speed required by most drone users, with airspeed being a key factor. When the airspeed of the drone changes, lift force and drag force will also change; changing airspeed can right control a drone. Most aircraft use differential pressure style airspeed meters composed of an airspeed tube and pressure sensor. By measuring the dynamic pressure and static pressure of the drone, users can make the necessary adjustments to ensure stable, consistent speeds.
TE's MEAS MS4515DO is a digital differential pressure sensor. It is a small, ceramic-based, PCB mounted pressure transducer from TE. The transducer is built using the latest CMOS sensor conditioning circuitry to create a low-cost, high-performance digital output pressure (14bit) and temperature (11bit) transducer designed to meet the strictest requirements from OEMs. The MS4515DO is fully calibrated and temperature compensated with a total error band (TEB) of less than 1.0% over the compensated range. The sensor operates from single supply of either 3.3 or 5.0Vdc and requires a single external component for proper operation. The rugged ceramic transducer is available in side port, top port, and manifold mount and can measure absolute or differential pressure from 2 to 30 inches H2O. The 1/8 barbed pressure ports mate securely with 3/32”ID tubing.