Moving 3-D Sensing Into Smartphones and Vehicles

Chirp Microsystems, a new startup from Berkeley, California, has developed a new Time of Flight (ToF) ultrasonic sensing platform for use in wearables and Virtual and Augmented Reality (VR/AR) systems. They have selected some big customers to whom they have made available their development platform.

At present, the high-end VR/AR systems are typically confined to a prescribed space, or tethered to a base station. The limit comes from the requirements of additional equipment in the space for creating better tracking experience. Usually, the additional equipment is often a magnetic sensor or a camera-based system that can correct drifting by using the inertial measurement unit (IMU) within the head units of the VR/AR system.

Chirp has demonstrated they can embed their miniaturized MEMS ultrasound sensors within the AR/VR head unit. With the sensors in place, the user has a 360-degree immersive experience, as the tracking system moves along with the user. Supporting inside-out tracking, the ultrasound sensors from Chirp can have controllers or input devices working with six-degrees of freedom—offering 3-D sensing.

VR/AR systems already use the optical or camera-based system for tracking. However, the camera is only a 2-D device, incapable of providing any sort of depth information. Even to detect if objects have shifted from one frame to another, a camera needs to use the point cloud, while applying very complicated calculations.

On the other hand, ToF ultrasound sensors can easily detect 3-D movement. This is because the technology is adept at triangulating data easily, and simpler calculations demand much less power.

Although it is another option for 3-D sensing, infrared technology has limited use when the sensor is outdoors—the heat outdoors tends to wash out infrared sensing. However, ultrasound sensors are robust and consume low power, and able to perform well in VR/AR systems outdoors, even in the presence of a bright sun.

While using the ToF ultrasound sensors in VR/AR systems, Chirp hopes the low-end VR/AR systems will improve the interactive experience, and smartphones and vehicles can start using the untethered high-end VR/AR systems.

For instance, smartphones use infrared technology currently as a proximity sensor. This actually prevents the user’s cheek from dialing the phone by itself. However, this requires the smartphone to have a tiny hole for the infrared sensor embedded on the face of the smartphone.

According to Chirp, some smartphone vendors have shown interest in replacing infrared with ultrasound. This would improve the aesthetics of the smartphone by removing the tiny hole on the face of the phone. Additionally, the ultrasound sensors can also add features such as autofocus when taking selfies, and add simple gesture functions to the phone.

At present, vehicles use bulky ultrasound sensors, for say, backing up. Chirp hopes to replace them with its ToF ultrasound sensors. They can also use the sensors as a User Interface (UI) inside cars for infotainment systems. However, as automotive applications tend to use long design-in cycles, Chirp is keeping this in low-priority for the time being. Chirp is planning to ramp up production of its ultrasound MEMS sensors and accompanying ASICS later this year.