Understanding Traffic Jam Assist (TJA): Your Cruise Control Buddy in Stop-and-Go Traffic

The lane keeping assistance system is one of the intelligent driving assistance systems. It can control the steering system on the basis of the lane departure warning system (LDWS) to assist the vehicle to stay in its own lane. It supports keeping the vehicle on the lane by recognizing the lane markers while the vehicle is driving with the help of a camera. If the vehicle is close to the recognized marker line and may deviate from the driving lane, the driver will be alerted by the vibration of the steering wheel or by sound, and the direction of the steering wheel will be slightly adjusted to correct the vehicle's course, keeping the vehicle on the correct lane. If the steering wheel detects no active intervention for a long time, an alarm will be sounded to remind the driver.

What is TJA Traffic Jam Assistance

1. What is TJA:

TJA (Traffic Jam Assistant) is a system designed to provide assistance to drivers in traffic jams, relieving driver fatigue.

It is an expanded version of the ACC function and can stop and go like the ACC, but with the added function of minor steering adjustment.

2. Condition for TJA function trigger and shut off :

The system can trigger this function when the speed is less than 65km/hr.

3. Safety of TJA function:

TJA is a driver assistance system. Drivers should be prepared to take over the vehicle control.

4. Visualization video of TJA function:

Here is an example of the Audi A8's official promo video, explaining the main principles of the TJA function : AUDI A8 TJA function official demonstration.

5. Communication principle diagram: Perception:

The distance sensor and front camera provide feedback on front vehicle flow, road boundary, lane width, front vehicle distance, self-vehicle steering angle and other information to the distance control unit.

Planning:

The distance control unit plans when to accelerate, decelerate and brake according to internal algorithms or standards.

Control:

Engine control unit implements acceleration, deceleration, and brake light control instructions following planned strategy; Steering control unit implements minor steering adjustment and other control instructions according to the planned strategy; Vehicle electronic control unit implements alarm signal prompts or release signal instructions according to planned strategy.

Physical Devices Perceived by TJA

Physical Devices (sensors) Perceived by TJA:

Ultrasonic radar, millimeter-wave radar, front view camera, etc.

Coverage area of the sensor:

Millimeter-wave radar senses the fence by the roadside

TJA system trigger:

When certain conditions are met, TJA system will prompt on the dashboard: “Traffic Jam Pilot available”.

There is a physical key marked “AUDI AI” on Audi cars, and TJA function can be triggered with one press, and the system takes over the control of the vehicle. However, the driver must keep their hands on the steering wheel and be ready to take over the control at any time.

At this point, the vehicle control system can control activities like vehicle steering and throttle.

The vehicle will follow the strategy, maintain the trailing distance, and constantly monitor if any vehicle is inserted in. it also makes the vehicle steering minor adjustment and following motion.

At the same time, the sensor also monitors the driver's readiness to take over the vehicle control system at any time, to prevent the driver from overly trusting the TJA system and neglecting it.

TJA system shut down:

After completing the traffic congestion assistance task, the system prompts the driver: Traffic Jam Pilot will be deactivated, Please take full control!!

Situations where TAJ function cannot be activated: The driver's hands leave the steering wheel (the steering wheel does not detect balance torque within a specified time) There is not enough lane width available (that's why the text mentioned monitoring road width) The radius of curvature of the lane <150m The vehicle is too close to the edge of the lane (why the text mentioned monitoring fences and coastal lines) The forward lane length is insufficient ...

When the above situations reach the limit value of the system strategy, the system will send a warning message to the driver, asking the driver to take over the vehicle control.

If the driver does not respond at all, the system will gradually decelerate at an acceleration of -2m/s? until it triggers the ESC to stop, and also flashes warning lights.