How do MEMS ultrasonic sensors promote the development of AR/VR technology?
Today, augmented reality/virtual reality (AR/VR) systems are increasingly being used in various fields, such as entertainment, education, healthcare and other industrial applications. With these technologies, users can simulate complex tasks, such as surgery, in a virtual space. Whether in AR or VR systems, sensing technology has become one of the key technologies.
Sensing technology helps users get a sense of reality in the virtual space through advanced and precise positioning/motion detection. TDK's latest AR/VR system uses time of flight (ToF) technology to measure the distance to an object, and ultrasonic sensors have attracted great attention.
●The challenge of making AR/VR more realistic: reducing the size of ultrasonic sensors
●ToF solution using MEMS-based ultra-small sensors
Challenge to make AR/VR more real: reducing the size of ultrasonic sensors
Since 2016, the price of various head-mounted display (HMD) AR/VR headsets has fallen, and the global AR/VR market has grown substantially. By 2025, the market is likely to exceed 11 billion US dollars (Source: "2017AR/VR Future prospects of relevant markets", Fuji Camry General Research Institute). In the past, AR/VR systems were mainly used in entertainment applications such as games, but their use in other fields is expected to increase, such as in assembly, manufacturing, transportation, retail, education, and healthcare.
In the latest AR/VR system, users can simulate complex surgical operations in a virtual space. The head-mounted display and hand controller with six degrees of freedom 6-DoF1* make this application possible. It can realize seamless synthesis between human movement in virtual space and human movement in real space. Its realization is based on a sensor technology called position tracking 2* and the function of measuring the distance to the object using the ToF method.
ToF technology measures the distance to the object based on the time difference between the light, infrared or ultrasonic wave from emission to the reflection of the object and back to the sensor. Whether it is optical or infrared ToF technology, although they are very accurate, they cannot be used for measurement in the presence of obstacles, nor are they suitable for measuring the distance to glass or other transparent objects. Ultrasonic ToF technology can accurately measure the distance to objects, even if these objects are highly reflective, and this technology will not be affected by the lighting conditions, size and color of the objects. Traditional ultrasonic ToF sensors require complex signal processing and are too large to be embedded in household appliances.
ToF solution using ultra-small MEMS-based sensors
TDK's solution to this challenge is CH-101, which is a new ultra-small ultrasonic ToF sensor whose volume is only one thousandth of the traditional ultrasonic ToF sensor. As the world’s first MEMS-based ultrasonic sensor, CH-101 is sold under the Chirp brand. It is a truly breakthrough product that combines piezoelectric micromachined ultrasonic transducers (PMUT3*), high-efficiency DSP (digital signal Processor 4*) and low-power CMOSASIC5* are combined together in a small package with a size of only 3.5x3.5x1.25mm.
Ultra-small sensor whose volume is only one thousandth of a traditional sensor
CH-101 combines PMUT, high-efficiency DSP (digital signal processor), and low-power CMOSASIC. It uses a small package with a size of only 3.5x3.5x1.25mm, and its volume is only one thousandth of a traditional ultrasonic ToF sensor One.
Bats can fly freely in the dark without hitting objects because they detect the position and relative speed of objects by emitting pulsed ultrasonic waves and receiving echoes from objects. This method is called echolocation, and the position tracking of ultrasonic sensors applies the same principle.
CH-101 has an embedded PMUT, which can emit ultrasonic pulses and receive echoes from objects within the sensor's field of view. Combining a variety of different signal processing technologies, the product can be used in a variety of applications, including detecting the distance and location of objects, sensing the presence of objects and avoiding collisions. In addition, it requires very low power consumption, one hundred times lower than the power consumption of traditional ultrasonic sensors, and has excellent environmental performance.
CH-101 ultrasonic sensor supports "Various VR"
The existing optical sensor-based VR system combines an external sensor with a wired headset and a controller. The former emits infrared rays and the latter can respond to infrared rays to locate the user's location. The VR system using CH-101 allows users to experience VR only by using headsets and controllers. The CH-101 ultrasonic sensor can be used in the independent headset ViveFocusPlus integrated machine developed by HTC.
The CH-101 ultrasonic sensor supports a maximum sensing range of 100cm, while the new product CH-201, which will be mass-produced at the end of 2019, supports a maximum sensing range of 500cm. Due to the use of MEMS technology, the size of sensors has become unprecedentedly compact. We expect them to achieve a range of applications, including AR/VR headsets, smart homes, drones, robots, smart phones, and wearable devices.
CH-101: Ultrasonic ToF sensor
CH-101 is a MEMS-based ultrasonic ToF sensor. Unlike an optical ToF sensor, it can accurately measure the distance to an object, regardless of the size, color, and transparency of the object. In addition, it will not be affected by environmental noise, such as noise and noise in the surrounding environment. For more information, please visit the Chirp website. Chirp (CH-101)
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