“ICU-10201 offers the sensitivity required for obstacle avoidance or proximity sensing, which is used frequently in robotics, drones and robot vacuum cleaners,” according to the company. “The sensor provides millimeter-accurate range measurements to targets at distances up to 1.7m, in any lighting condition including full sunlight, independently of the target’s color and optical transparency, like glass or mirrors.”
1.7m is to a wall, reducing to 1.1m for a 58mm diameter post. Accuracy is affected by the speed of sound’s 0.2%/°C drift. Minimum range is 100mm, although objects can be detected, and sometimes ranged, down to 30mm.
The chip is 1.26 mm tall and its top has a central sound port whose field-of-view is approximately hemispherical, but can be reduced using an external horn where increasing diameter results in narrow beams – the company offers design data for several horns. Sonically operation is nominally 175kHz – resonance varies across 173 to 181kHz through manufacturing tolerance.
The internal 40MHz microcontroller can process the raw sensor readings into range (simultaneously to several objects), or events such as presence. This is communicated to a host over SPI operating at 13MHz and 1.8 or 3.3V.
“Several available algorithms can further process the echo information for a variety of usage cases in a range of applications including range-finding, human presence and wake-on approach,” said TDK.
SonicLib is asoicated driver software for the host microcontroller, written in C and intended to be compiler and microcontroller- independent.
It controls one or more ICU-10201s attached to one or more host SPI ports on the host processor, and allows programming, configuration, triggering and read-out data from the sensors. “The driver only requires the customer to implement an I/O layer which communicates with the host processor’s SPI hardware and GPIO hardware,” said TDK.
Techniques are available to allow several of the devices to operate in the same location – no precautions are needed beyond 4m separation.
A special version – ICU-10201-PC (‘pitch-catch’) is available for situations where one device needs to act as the transmitter for another or several other devices nearby. This has a narrower (176 to 178kHz) part-to-part resonant frequency variation.
Three power rails are needed: analogue (1.71 to 1.89V), digital (same) and IO (1.71 to 3.63V).
Consumption (analogue+digital, not IO) for a single CU-10201 depends on range and update rate. Examples are: 14µA (0.5m max 1sample/s), 17µA (1m max 1sample/s, 212µA (0.5m max, 50sample/s) or 320µA (1m max, 50sample/s).
Operation is across -40 to 85°C.
Potential applications are: Obstacle avoidance for robots and drones, cliff drtection for vacuum cleaners, soft surface identification and liquid level measurement – the latter in coffee machines, for example.
