Pololu Distance Sensor with Pulse Width Output, 130cm Max
This small lidar-based distance sensor reports the distance of objects up to about 130 cm (50″) away with a pulsed signal similar to a hobby servo control signal. A digital microcontroller pin can be used to time the length of each high pulse, which encodes the measured distance. The sensor works over an input voltage range of 3.0 V to 5.5 V, and the 0.1″ pin spacing makes it easy to use with standard solderless breadboards and 0.1″ perfboards.
Note: The maximum range of 130 cm is only achievable for high-reflectance objects in good ambient conditions. Lower-reflectivity targets or poor ambient conditions will reduce the maximum range.
This compact sensor makes it possible to measure the distance of objects up to about 130 cm (50″) away using a simple digital pulse width interface (similar to a hobby servo control signal). It uses a short-range lidar module to precisely measure how long it takes for emitted pulses of infrared, eye-safe laser light to reach the nearest object and be reflected back, allowing for 1 mm resolution. As long as the sensor is enabled, it takes continuous distance measurements and encodes the ranges as the widths of high pulses, which can then be timed by a microcontroller using a single digital input.
A camera with no IR filter shows the infrared light emitted by a Pololu Digital Distance Sensor.
The relationship between measured distance d (in mm) and pulse width t (in µs) is as follows:
The timing uncertainty is approximately ±5%. As objects approach the sensor, the output pulse width will approach 1.0 ms, while an object detected at 130 cm will produce a 1.65 ms pulse width. The sensor uses a pulse width of 2.0 ms to indicate no detection. The pulse period T ranges from around 9 ms to 10 ms, depending on the proximity of the detected object.
The maximum detection range depends on object reflectivity and ambient lighting conditions. In our tests, the sensor was able to reliably detect a white sheet of paper out to its maximum range of 130 cm, and it could reliably detect a hand out to around 80 cm away. The following graph shows the measured distances of three units versus their actual distances from a variety of targets at several different ranges:
Please note that while this sensor can detect objects to within about 1 mm of the sensor face, the effective minimum distance it can measure is around 4 cm, so objects closer than 4 cm might result in an inaccurate measurement.
- Operating voltage: 3.0 V to 5.5 V
- Current consumption: 30 mA (typical) when enabled, 0.4 mA when disabled
- Maximum range: approximately 130 cm (50″) (for high-reflectivity targets in good ambient conditions; lower-reflectivity targets or poor ambient conditions will reduce the maximum detection range)
- Minimum range: 4 cm (for accurate measurement); < 1 mm (for detection)
- Update rate: 100 Hz to 110 Hz (10 ms to 9 ms period)
- Field of view (FOV): 15° typical; can vary with object reflectance and ambient conditions
- Output type: digital pulse width
- Dimensions: 0.85″ × 0.35″ × 0.136″ (21.6 × 8.9 × 3.5 mm)
- Weight: 0.014 oz (0.4 g)