Motion, position, and environmental sensors

The Android platform supports mainly three broad categories of sensors: the motion, position, and environment-based sensors. This categorization is done based on the type of physical quantity detected and measured by the sensors.

Motion sensors

Motion sensors are responsible for measuring any kind of force that could potentially create motion in the x, y, and z axes of the phone. The motion could be either a linear or angular movement in any direction. This category includes accelerometers, gravity, gyroscope, and rotational vector sensors. Most of these sensors will have values in the x, y, and z axes, and the rotational vector will especially have extra value in the fourth axis, which is the scalar component of the rotation vector.

The following table summarizes the motion sensor usage, types, and power consumption:

Sensor	Type	Value	Underlying Sensors	Description	Common Usage	Power Consumption
Accelerometer	Physical	Raw	Accelerometer	This measures the acceleration force along the x, y, and z axes (including gravity). Unit: m/s2	It can be used to detect motion such as shakes, swings, tilt, and physical forces applied on the phone.	Low
Gravity	Synthetic	Fused	Accelerometer, Gyroscope	This measures the force of gravity along the x, y, and z axes. Unit: m/s2	It can be used to detect when the phone is in free fall.	Medium
Linear Acceleration	Synthetic	Fused	Accelerometer, Gyroscope	It measures the acceleration force along the x, y, and z axes (excluding gravity). Unit: m/s2	It can be used to detect motion such as shakes, swings, tilt, and physical forces applied on phone.	Medium
Gyroscope	Physical	Raw, Calibrated	Gyroscope	This measures the rate of rotation of the device along the x, y, and z axes. Unit: rad/s	It can be used to detect rotation motions such as spin, turn, and any angular movement of the phone.	Medium
Step Detector	Synthetic	Calibrated	Accelerometer	This detects walking steps.	It can be used to detect when a user starts walking.	Low
Step Counter	Synthetic	Calibrated	Accelerometer	It measures the number of steps taken by the user since the last reboot while the sensor was activated	It keeps track of the steps taken by the user per day.	Low
Significant Motion	Synthetic	Calibrated	Accelerometer	It detects when there is significant motion on the phone because of walking, running, or driving.	It detects a significant motion event.	Low
Rotation Vector	Synthetic	Fused	Accelerometer, Gyroscope, Magnetometer	This measures the rotation vector component along the x axis (x * sin(θ/2)), y axis (y * sin(θ/2)), and z axis (z * sin(θ/2)). Scalar component of the rotation vector ((cos(θ/2)). Unitless.	It can be used in 3D games based on phone direction.	High

Position sensors

Position sensors are used to measure the physical position of the phone in the world's frame of reference. For example, you can use the geomagnetic field sensor in combination with the accelerometer to determine a device's position relative to the magnetic North Pole. You can use the orientation sensor to determine the device's position in your application's frame of reference. Position sensors also support values in the x,y, and z axes.

The following table summarizes the position sensor's usage, types, and power consumption:

Sensor	Type	Value	Underlying Sensors	Description	Common Usage	Power Consumption
Magnetometer	Physical	Raw, Calibrated	Magnetometer	This measures the geomagnetic field strength along the x, y, and z axes. Unit: μT	It can be used to create a compass and calculate true north.	Medium
Orientation (Deprecated)	Synthetic	Fused	Accelerometer, Gyroscope, Magnetometer	This measures the Azimuth (the angle around the z axis), Pitch (the angle around the x axis), and Roll (the angle around the y axis). Unit: Degrees	It can be used to detect the device's position and orientation.	Medium
Proximity	Physical	Raw	Proximity	This measures the distance of an object relative to the view screen of a device. Unit: cm	It can be used to determine whether a handset is being held up to a person's ear.	Low
Game Rotation Vector	Synthetic	Fused	Accelerometer, Gyroscope	This measures the rotation vector component along the x axis (x * sin(θ/2)), y axis (y * sin(θ/2)), and z axis (z * sin(θ/2)). It is the scalar component of the rotation vector (cos(θ/2)). Unitless. It is based only on the Gyroscope and Accelerometer and does not use the Magnetometer.	It can be used in 3D games based on phone direction.	Medium
Geomagnetic Rotation Vector	Synthetic	Fused	Accelerometer, Magnetometer	This measures the rotation vector component along the x axis (x * sin(θ/2)), y axis (y * sin(θ/2)), and z axis (z * sin(θ/2)). It is the scalar component of the rotation vector (cos(θ/2)). Unit less. * It is based only on the Magnetometer and Accelerometer and does not use the Gyroscope.	It can be used in augmented reality apps, which are based on the phone and compass direction.	Medium

Environmental sensors

Environment sensors are responsible for measuring environmental properties, such as temperature, relative humidity, light, and air pressure near the phone. Unlike motion and position sensors, which give sensor values multi-dimensional arrays, the environment sensors report single sensor values.

The following table summarizes the environment sensor's usage, types, and power consumption:

Sensor	Type	Value	Underlying Sensors	Description	Common Usage	Power Consumption
Ambient Temperature	Physical	Raw	Thermometer	This measures the ambient air temperature. Unit: Degrees Celsius	It is used for monitoring temperatures.	Medium
Light	Physical	Raw	Photometer	This measures the ambient light level (illumination). Unit: lx	It can be used to dim the screen brightness of the phone.	Low
Barometer	Physical	Raw	Barometer	This measures the ambient air pressure. Unit: mPa or mbar	It can be used to measure height relative to sea level.	Medium
Relative Humidity	Physical	Raw	Relative Humidity	This measures the relative ambient humidity in percentage. Unit: %	It can be used for calculating the dew point, and absolute and relative humidity.	Medium