UAVs

Pressure sensors serve two distinct functions in UAV systems. The first is altitude measurement: an absolute pressure sensor measures atmospheric pressure, and the flight controller converts it to altitude above sea level or above the takeoff point, providing the continuous altitude reference that autonomous flight, terrain following, obstacle avoidance, and return-to-home behavior depend on. Atmospheric pressure changes by about 12 pascals per meter near sea level, so one-meter altitude resolution requires pressure resolution at the pascal level or below. The second function is aerodynamic sensing: differential pressure measurements quantify dynamic pressure from airflow. On fixed-wing platforms, this translates directly to airspeed, and on multirotor platforms, it provides information on wind loads and flight-envelope conditions. Both functions require stable, accurate sensors capable of resolving small pressure changes in an environment that generates significant pressure noise.

UAVs impose demanding measurement conditions that distinguish them from other pressure-sensing applications. Brushless motors and propellers generate vibration across a broad frequency spectrum, and on small platforms, the sensor is often mounted close to the motors with limited vibration isolation. Wind, aerodynamic turbulence, and propwash create rapid pressure fluctuations superimposed on the steady-state readings the flight controller uses to compute altitude and airspeed. Multirotor UAVs continuously change orientation during normal flight: pitching nose-down to accelerate, banking to turn, and pitching nose-up to decelerate. Each attitude change shifts the sensor’s orientation relative to gravity, and sensors that are not position-insensitive shift their zero point with the attitude change, introducing altitude error that varies with the aircraft’s maneuver state. Unlike manned aircraft, UAVs have no pilot to detect drifting readings or intervene when sensor data produces unexpected flight behavior.

Superior Sensor’s ND Series covers the pressure measurement requirements across UAV platforms and applications with three variants. The Low Pressure sensor addresses differential pressure measurements for low-range airspeed and aerodynamic sensing. The Mid Pressure sensor handles higher-range gauge and differential measurements in propulsion and hydraulic systems on larger platforms. The Absolute Pressure sensor provides the barometric altitude reference that flight controllers use for altitude hold, terrain following, and autonomous navigation. The extended operating temperature range, position insensitivity rated to within 0.25 pascals, and advanced digital filtering address the specific conditions under which UAVs operate, conditions that eliminate generic industrial sensors from consideration.

Why Choose Superior Sensor for UAVs

UAV pressure sensors must resolve small altitude changes despite propulsion vibration, maintain accurate readings during aggressive attitude changes, and update quickly enough to support high-frequency flight control loops, all while adding minimal weight and complexity to the avionics stack. Superior Sensor’s ND Series meets each of these requirements across the full range of UAV pressure measurement applications.

Recommended Sensors

Common Device Features: 3.3V supply
Long-Term Stability is measured after first 12 months
Short-Term Error Band (STEB) is measured over 24 hours, after auto-zero

Common Specifications

UAV FAQ

How do UAVs use pressure sensors to measure altitude?

UAVs measure altitude by comparing atmospheric pressure at the aircraft’s current position to a reference pressure, typically the pressure recorded at takeoff. Atmospheric pressure decreases predictably with altitude: near sea level, it drops about 12 pascals per meter of altitude gain. An absolute pressure sensor measures the total atmospheric pressure at the UAV’s location, and the flight controller converts this to altitude using the barometric formula. This altitude reference drives altitude hold mode, terrain following, return-to-home behavior, and geofencing limits that prevent the UAV from exceeding its authorized operating altitude. The accuracy of altitude hold depends directly on the accuracy and stability of the pressure sensor. A sensor that drifts over time produces a drifting altitude reading, and the flight controller responds by commanding the aircraft to maintain the wrong altitude, since it has no independent altitude reference to compare against.

Why does position insensitivity matter specifically for multirotor UAVs?

Multirotor UAVs continuously adjust attitude during normal flight. Accelerating forward requires pitching the airframe nose-down, sometimes by 20 to 30 degrees. Banking for a turn rolls the aircraft. Stopping requires pitching nose-up. Each attitude change shifts the pressure sensor’s orientation relative to gravity. Pressure sensors that are not position-insensitive shift their zero point in proportion to the orientation change, producing a reading that includes both the actual pressure and an orientation-dependent error. Because altitude is computed from pressure, this error appears as a false altitude change: the flight controller sees the altitude shift as the UAV pitches forward to accelerate and may increase the throttle to correct what it interprets as an altitude loss. On an autonomous UAV with no pilot override, this feedback loop between attitude changes and altitude-control responses can degrade altitude-hold precision and produce oscillatory behavior. The ND Series position insensitivity, rated to within 0.25 pascals, prevents attitude changes from contaminating altitude readings.

What makes motor vibration a challenge for UAV pressure sensing?

Brushless DC motors and the propellers they drive generate vibration across a broad range of frequencies. Each propeller blade passing a fixed reference point creates a pressure pulse at a frequency equal to the motor RPM multiplied by the number of blades. On a multirotor with multiple motors running at different speeds, the vibration spectrum contains multiple fundamental frequencies and their harmonics, spanning a wide bandwidth. This vibration is transmitted through the airframe to every component, including the pressure sensor. The sensor’s measurement element responds to these mechanical vibrations as apparent pressure changes, introducing noise into altitude and airspeed readings at the frequencies where the flight control system is trying to resolve real pressure signals. On small UAVs, where the sensor is mounted close to the motors with limited vibration isolation, this noise can be large relative to the pressure differences the sensor is trying to resolve. Superior Sensor’s digital filter removes this vibration-induced content at the front end, before it reaches the flight controller.

How does pressure sensor response time affect UAV flight control performance?

Multirotor flight controllers run altitude control loops at high update rates because multirotor platforms are inherently unstable and require continuous correction to maintain attitude and altitude. The altitude control loop uses pressure sensor data to compute altitude error and generate throttle commands that keep the aircraft at its target altitude. If the pressure sensor updates more slowly than the control loop runs, the loop must act on stale data, reducing its effective bandwidth and degrading its ability to reject external disturbances such as wind gusts. At low update rates, the altitude controller effectively receives altitude information at a fraction of its intended update rate, with corresponding reductions in altitude-hold precision and disturbance-rejection performance. The ND Series 2-millisecond update rate meets the speed requirements of high-frequency flight control loops, ensuring altitude readings are current at each control-loop iteration rather than a step behind.

What pressure ranges are used across different UAV applications?

UAV pressure sensing spans several measurement types and magnitudes, depending on the platform and application. Barometric altitude measurement uses absolute pressure sensors covering the range from sea level (approximately 101 kPa) down to the UAV’s maximum operating altitude, which for specialized platforms may extend to several thousand meters, where pressure falls below 90 kPa. Differential airspeed measurement on fixed-wing UAVs and some multirotor platforms uses low-range differential pressure sensors from near zero to a few hundred pascals, depending on the platform’s airspeed range. Altitude resolution requirements push the low end: resolving one meter of altitude near sea level requires resolving approximately 12 pascals, which places demanding accuracy and stability requirements on the sensor. The ND Series Low Pressure, Mid Pressure, and Absolute Pressure variants cover the differential, gauge, and absolute measurement requirements across the range of UAV platforms and applications.