Nidec Elesys developed new milliwave radar device installed inside vehicle

Tinuku - Nidec Elesys Corp, a manufacturer of in-vehicle electronic devices, developed a technology that enables to use a milliwave radar device in the interior of a vehicle for recognizing objects around the vehicle, planning to start volume production in or after the fall of 2019.

Milliwaves with a frequency of 76-77GHz are attenuated when they are passing through glass. A radar device is placed in the interior of a vehicle, its detection range is halved. Therefore, radar devices are usually placed in a front grille. As a result, they are sometimes tainted by dirt, affecting detection range and accuracy.

Tinuku Nidec Elesys developed new milliwave radar device installed inside vehicle

Nidec Elesys developed a technology to increase power output from an antenna by more than 100% without changing power input to the antenna, which is regulated by law. As a result, it became possible to use an in-vehicle radar device and detect objects about 200m away from the vehicle, which is the same detection range as a radar device installed outside the interior of a vehicle (e.g. in a front grille).

The company also developed a sensor system integrating a monocular camera. The integrated system can be installed on the rear side of a rear-view mirror as in the case of existing monocular cameras. Moreover, the system has a function to process signals for realizing an automatic brake, etc.

Nidec Elesys considers that the camera-integrated system can be produced at a lower cost than existing products having equivalent functions.

"We aim to have it employed not only for high-grade vehicles but also for a wide variety of vehicles including low-priced cars," said Toshiyuki Mieno, executive officer, manager of Advanced System Research & Development Center at Nidec Corp as parent company of Nidec Elesys.

It is possible to form an antenna mainly by using plastic to reduce its weight. Taking advantage of the low price and light weight, Nidec Elesys expects the system to be employed not only for vehicles but also for drones. Also, the company intends to sell it for agricultural machines that are expected to have autonomous driving function and AGVs (automatic guided vehicles). Nidec Elesys developed new milliwave radar device installed inside vehicle

Furthermore, with the newly-developed milliwave antenna, it becomes possible to generate milliwave beams by using phased array technology, enabling to realize a function equivalent to the function of LiDAR (light detection and ranging), which three-dimensionally recognizes space.

Loss at waveguide reduced by 90%

Nidec Elesys increased the output of the antenna by drastically reducing loss at the waveguide that guides milliwave signals to the antenna. The path of electric waves (ridge) is surrounded by many protrusions looking like an instrument for making waffles (confection) so that the waves do not leak to the outside.

Compared with the case in which a strip line-based planar antenna, which is normally used for milliwaves, is used, with the new method, there is almost no loss at the waveguide. Loss can be reduced by about 90%, according to Nidec Elesys.

The efficiency of the entire antenna is about 20% in the case of a planar antenna. This time, however, the efficiency is 70-80%. The antenna is a horn type. The antenna gain of a prototype is 25dBi. The detection angle is as wide as 90. Nidec Elesys developed new milliwave radar device installed inside vehicle

Nidec Elesys calls the waveguide "waffle iron ridge waveguide (WRG)." The WRG does not use a dielectric material as a supporting material for forming a waveguide and, therefore, does not cause dielectric loss. Also, it becomes easier to make an antenna in accordance with design specifications.

In the case of existing antennas using a dielectric material, it is difficult to accurately control the anisotropy of the dielectric constant of a dielectric material. As a result, antennas sometimes cannot be made in accordance with design specifications.

Moreover, it becomes easier to reduce size because a horn antenna can be formed like an array on the front side and a waveguide can be formed on the rear side. In the case of a planar antenna, a waveguide and antenna are formed on the same substrate. So, it is necessary to increase area in order to obtain a certain level of output.