77Ghz single-chip millimeter wave sensor enables automatic parking

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77Ghz single-chip millimeter wave sensor enables automatic parking [Copy link]

By Kishore Ramaiah, Texas Instruments

Have you ever spent time looking for a parking spot at a shopping mall or grocery store, wishing you could just drop off at the entrance and park yourself, especially if it’s raining or the weather is extremely hot? How much time would you save if you didn’t have to look around for a parking spot? (Or how much money would you save if you didn’t have to pay for valet parking?). Self-parking is quickly becoming a reality, and automakers are using millimeter-wave (mmWave) radar sensors to make it possible.

You might be wondering: Are surround cameras and ultrasonic sensors already capable of parking? Today’s sensors provide parking assistance, in other words, the driver still has to make a judgement call based on the feedback given by the sensors. So the car is still not fully autonomous.

Autonomous parking requires first identifying an empty parking space or “free space” at a distance of about 40 meters. This is its “search mode”. Once an open space has been identified, the car needs to maneuver into it and park itself, which is called “parking mode”.

To enable automated parking, sensors should be able to detect objects such as other vehicles, curbs, and pedestrians from 3 cm to over 40 m across a wide field of view in all environmental conditions. mmWave sensors help enable this by accurately detecting smaller objects at distances less than 25 cm, such as metal bars protruding from the ground, which may not be effectively sensed by other sensing modalities. mmWave sensors also continue to operate in a variety of weather and lighting conditions.

Sensor Mounting

Installing sensors in cars is a major challenge today. Since mmWave sensors can be easily mounted behind the bumper, car owners do not need to drill holes in the body or chassis. The ability of mmWave to pass through solid materials such as plastic and bumpers allows for standardized installation regardless of car manufacturer or car model. The number of sensors required to achieve 360-degree sensing around the car is also much smaller than other sensing modalities. Only eight sensors are required around the car to achieve 360-degree sensing, as shown in Figure 1.

Figure1: Millimeter wave sensors can provide 360degree sensing around the car to enable automatic parking applications

Multi-mode sensors

Automatic parking is achieved by repurposing existing front and rear corner radars (multi-mode). When the car is in driving mode, these sensors can be used as blind spot detection sensors or lane change assist sensors, which can support detection of cars in other lanes within a distance of 80 meters. When the car is in search or parking mode, the configuration of the sensors changes dynamically to enable sensing of objects at close range, ranging from 40 meters to less than 10 cm to match the range of parking applications. Multi-mode obstacle detection sensors for the doors can also be used for parking applications. Based on these characteristics, mmWave sensors are becoming increasingly attractive to top automakers. Table 1 lists the advantages of using mmWave sensors for automatic parking applications.

Features	Advantages
Long detection range	Pedestrians and other objects at a distance greater than 40 meters
[p=21, null, left left]Wide field of view	Perceive objects in the 3D space around the car
Repurpose corner radar sensors	Reduce the number of sensors required at the system level
Multi-mode capabilities	Dynamic sensing of objects at 40 meters or 5 meters

Table1: System-level benefits of using mmWave sensors for automated parking applications

The Texas Instruments (TI) AWR1843 is a 77 GHz single-chip mmWave sensor that integrates digital signal processing, memory, and a radar acceleration unit to enable automated parking applications, as shown in Figure 2.

图 2: Components of AWR1843 parking chip Table 2 shows the application advantages of AWR1843: Features Advantages of AWR1843 left]Three sets of transmit antennas

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Detect objects in the azimuth and elevation planes

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DSP and on-chip memory

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Efficiently handle complex algorithms on the chip

[/td][/tr] [tr][td=206]

Radar accelerator unit

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Performs Fast Fourier Transform operations in hardware to accelerate the process

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5 degree phase rotator for each transmit antenna

[/td][td=362][p=21, null, left left]Perform beamforming to enhance object detection

[/td][/tr] [/table]

Table2:AWR1843Device features and application benefits

Automakers and top OEMs are increasingly adopting mmWave sensors to provide a variety of driver assistance and automatic parking features. This is mainly due to the features and advantages offered by mmWave - higher integration, (meaning smaller size). It can help autonomous driving.

null, left]Radar Accelerator Unit

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Performs Fast Fourier Transform operations in hardware to accelerate the process

[/td][/tr] [tr][td=206]

5 degree phase rotator per transmit antenna

[/td][td=362]

Performs beamforming to enhance object detection

[/td][/tr] [/table]

Table2:AWR1843Device Features and Application Benefits

Automakers and top OEMs are increasingly adopting mmWave sensors to provide various driver assistance and automatic parking features. This is mainly because of the functions and advantages offered by mmWave - higher integration, (meaning smaller size). It can help autonomous driving.

null, left]Radar Accelerator Unit

[/td][td=362]

Performs Fast Fourier Transform operations in hardware to accelerate the process

[/td][/tr] [tr][td=206]

5 degree phase rotator per transmit antenna

[/td][td=362]

Performs beamforming to enhance object detection

[/td][/tr] [/table]

Table2:AWR1843Device Features and Application Benefits

Automakers and top OEMs are increasingly adopting mmWave sensors to provide various driver assistance and automatic parking features. This is mainly because of the functions and advantages offered by mmWave - higher integration, (meaning smaller size). It can help autonomous driving.