Driving assistance


  • Driving assistance
  • Radar
  • Lidar

Driving assistance:
Systems that fall under the term “driving assistance” support the driver in driving. In general, the driving assistance serves to increase safety. Often several systems work together to achieve the desired effect. The following systems can be classified under the driving assistance:

  • LDW (Lande Departure Warming). Function: notification when crossing the lane demarcation;
  • TSR (Traffic Sign Recognition). Function: recognize traffic signs and draw the driver's attention to them;
  • ACC (Active Cruise Control). Function: automatically keep a distance from the vehicle in front;
  • BSD (Blink Spot Detection). Function: notification of vehicles in the blind spot;
  • ALC (Adaptive Light Control). Function: automatically switch the lighting on and off and sometimes also rotate the reflector;
  • Pre-crash systems. Function: automatic braking to avoid collisions;
  • Pedestrian detection. Function: pedestrian detection;
  • Rain/light detection. Function: Automatically turn on and off windshield wipers when it detects rain;
  • HDC (Hill Descent Control). Function: descent assistance;
  • Hill hold/start assist. Function: apply the parking brake when stationary on a hill and release it when driving away;
  • Surround view system. Function: all-round vision system by means of various cameras;
  • Adaptive high beam/curve lighting. Function: anti-glare system for oncoming traffic;
  • Automatic parking. Function: automatic parking system;
  • Driver drowsiness detection. Function: Detection of driver alertness, e.g. falling asleep.
  • Navigation system. Function: Navigate to the specified destination. With a hybrid car, the charge status can be adjusted on the specified route.

A combination of the above systems forms the basis for an autonomously driving car. Components such as radar, video cameras and ultrasonic sensors are an extension of the aforementioned systems.

Radar has been used for a number of years to control automatic speed, braking and safety systems in response to sudden changes in traffic conditions. The main task of the radar sensor is to detect objects and then determine their speed and position relative to the vehicle on which the sensors are mounted. To achieve this, the radar sensor has four antennas that simultaneously emit radar waves with a frequency usually between 76 and 77 GHz. These waves are reflected by the object and are received by the antennas. The positions of the objects can be determined by comparing the phase differences and the amplitudes of the signal echoes.

The table below shows the different automotive applications for which the radar is used.

A distinction is made between three types of radar systems: Short-Mid- and Long-range radar.

  • Short Range Radar (SRR)
    Reverse parking: In automatic parking, ultrasonic sensors are too slow for the computer to detect the distance between two cars, so the SRR is also used here.
    Pedestrian recognition: the system also intervenes in unclear situations if a pedestrian approaches. If there is no response in time, the vehicle brakes automatically.
  • Mid Range Radar (MRR)
    Cross Traffic Alert: When the driver reverses out of the parking space in a clear situation, the system warns of approaching vehicles (see image below).
  • Long Range Radar (LRR)
    Active Cruise Control (ACC): With a range of 150 to 250 meters with a vehicle speed detection of 30 to 250 km/h, the LRR is suitable as a radar system for active cruise control. The distance to the vehicle in front can be set by the driver. Often 4 to 8 phases are possible. Each phase is a number of meters. The operation of the active cruise control is explained below.
1. Cruise control is on. The vehicle travels at the set speed.
2. The vehicle in front drives slower; the vehicle brakes. The cruise control remains on.
3. The vehicle maintains a certain distance from the vehicle in front.
4. As soon as the radar sensor detects no obstacles, the vehicle accelerates back to the set speed.

The Automatic Distance Control (ADC) is thus able to perform a braking intervention when an object is registered. The images below are of the ACC (Active Cruise Control) of a Volkswagen Phaeton.

The electrical installation of the ACC is shown in the following diagrams. G550 is the sensor for the automatic distance control. The wires from pins 4 and 5 refer to 17 and 18 in the following diagram.

Reference is made to positions 17 and 18 in the diagram below. These appear to be CAN (Extended Low) bus wires (B665 and B666) connected to control unit J533. Via CAN bus drive high (B383 and B390), J533 communicates with J539 (brake servo control unit). The following diagram shows several connections to this control unit.

Control unit J539 controls the N374 valve for ADR (Automatic Distance Regulation) and the F318 (servo on the brake booster) for brake intervention. The CAN-high (B383) and CAN-low (B390) wires from the previous diagram can also be seen here.

LIDAR (Light Detection And Ranging or Laser Imaging Detection And Ranging is a technology that determines the distance to an object or surface by means of the use of laser pulses. Lidar works similar to that of radar: a signal is emitted and will some time later by reflection again. The distance to this object is determined by measuring this time. The difference between lidar and radar is that lidar uses laser light while radar uses radio waves. This allows lidar to detect much smaller objects than with radar.The wavelength of radio waves is around 1 cm, that of laser light between 10 m (ir) and 250 nm (uv). At this wavelength, the waves will be better reflected by small objects.

A lidar sensor transmits a modulated, continuous infrared signal, which is reflected by an object and received again by one or more photodiodes in the sensor. The modulated signal may consist of square waves, sinusoidal oscillations or pulses. The modulator sends the received signal to the receiver. The received signal is compared with the transmitted signal to check whether there is a phase difference and to check the time between transmission and reception. The distance to the object is determined from this data.

Lidar systems operate at the speed of light, which is more than 1.000.000 times faster than the speed of sound. Instead of emitting sound waves, they send and receive data from hundreds of thousands of laser pulses every second. An on-board computer registers the reflection point of each laser and translates this quickly-updated “point cloud” into an animated 3D representation of its environment.

Not only is the object shown on a screen, the computer also estimates which movements the object can make. A vehicle can move quickly forwards and backwards, but not sideways. However, a person can move in any direction, but at a relatively slow speed. The lidar system always makes a snapshot of the situation in which the car is. The driving assistance makes more than a hundred choices every minute in order to be able to drive safely.

The composition of a lidar sensor is as follows:

  • Light Source: This can be a laser, LED, or VCSEL diode that emits light in pulses;
  • Scanner and optics: these parts guide the light out through a mirror or lens. The lens focuses the reflected light to a photo detector;
  • Photo detector and electronics; the light is collected in a photo detector, for example a photodiode. The electronics process the image data digitally;
  • Position and navigation system: Mobile lidar systems require a GPS system to determine the exact position and orientation of the sensor.

Autonomous driving with Lidar:

  • Google combines lidar and radar;
  • Intel relies entirely on camera technology.
  • Agreement between manufacturers: they combine visual (camera) images with sensor information.
  • When one system fails, the other technology will still detect and intervene to enter a safe mode.
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