Setra is playing it safe: New milestones Active Brake Assist 5 and Active Drive Assist 2 – the way to automated touring coach driving

Sep 18, 2022
  • Active Brake Assist 5 Milestone in safety development
  • Active Drive Assist 2: Smart introduction to automated driving
  • Numerous other new functional equipment increases safety

Setra is synonymous with touring coach safety. Many safety and assistance systems have made their premiere in a Setra touring coach – the range of innovations extends from the retarder to the anti-lock braking system and Sideguard Assist turn-off assistant, to name just a few examples. Setra’s integrated safety concept helps to proactively prevent accidents. It protects both passengers and the driver and involves the weaker road users. The next generation of coaches underlines the high safety standard with spectacular innovations in terms of assistance systems. Setra TopClass and ComfortClass are based on a further developed electrical/electronic platform. Among other things, it forms the basis for the latest generation of assistance systems. With them, Setra TopClass and ComfortClass are setting industry-wide standards in their segments and far beyond. The optional Active Drive Assist 2 enables semi-automated driving in a touring coach for the first time. Standard Active Brake Assist 5 (ABA 5) is the world’s first emergency brake assistant that can respond to moving and stationary pedestrians with maximum full-stop braking.

Active Drive Assist 2: Smart introduction to automated driving

Accelerating, braking, maintaining the distance, steering, staying in lane and even an emergency stop – the new Active Drive Assist 2 is a decisive step on the way to automated driving with touring coaches. Active Drive Assist 2 actively supports the driver by combining various assistance systems to maintain the distance and keep the vehicle in lane. The system can brake, accelerate and keep the vehicle in the lane by active steering movements. For this purpose, it uniquely combines the functions of the individual systems and thus already enables semi-automated driving in all speed ranges.

With Active Drive Assist 2, all assistance systems work hand in hand and complement each other: In this way, Active Drive Assist 2 operates according to the specifications of Predictive Powertrain Control (PPC) in order to ensure the most economical driving style possible. The system uses functional enhancements based on the tried-and-tested Adaptive Cruise Control (ART) and the Lane Assist for longitudinal and lateral guidance of the vehicle. In addition, Active Drive Assist 2 relies on the same advanced radar and camera technology as Active Brake Assist 5 (ABA 5) to detect the traffic ahead. An emergency stop function has also been integrated. This brings the vehicle to a standstill through moderate, automated braking when the driver no longer reacts.

An essential component of Active Drive Assist 2 is the active lateral guidance within the lane by Active Steering Assist with an electric motor as support for the hydraulic steering and the connection with the longitudinal guidance of the adaptive cruise control (acceleration/braking/maintaining distance) through the fusion of radar and camera information.

With Active Steering Assist, Active Drive Assist 2 additionally keeps the touring coach within the lane by means of continuous steering interventions at a target position that can be set by the driver when ART is activated. The driver can choose between three settings: Either the bus keeps exactly to the center of the lane or, depending on the width of the lane, slightly offset by ten to 20 centimeters to the left or right. The system therefore considerably relieves the driver by taking care of a large part of the continuous, minor steering corrections required to keep the vehicle in lane. Like ART, active lateral guidance by Active Steering Assist is active throughout the touring coach's entire speed range between 0 and 100 km/h. Requirements for the system: The lane must be clearly marked by lines on both sides.

A green steering wheel symbol in the central display signals to the driver that Active Steering Assist is assisting them in lateral guidance of the vehicle. If the driver wishes to do without this due to the current traffic situation, they can deactivate Comfort Support.

Even when Active Drive Assist 2 is deactivated, the tried-and-tested Adaptive Cruise Control continues to take care of the longitudinal guidance of the vehicle, in conjunction with Predictive Powertrain Control (PPC) predictive cruise control. Adaptive cruise control slows down the touring coach before coming too close to a vehicle ahead to then accelerate it back up to the speed set by the driver. If necessary, adaptive cruise control can even slow down the touring coach to a standstill with partial braking.

Active Drive Assist 2 has been developed for driving on highways and roads similar to multi-lane roads, which is why a minimum lane width is required. The system switches to passive mode upon reaching system limits such as unclear lane markings, excessively narrow lanes or excessively tight curve radii. This is accompanied by a warning to the driver, signaled by a corresponding display in the cockpit.

Despite the support provided by Active Drive Assist 2, the driver always remains responsible. If the driver takes their hands off the steering wheel, a warning cascade is triggered in accordance with the legal requirements (hands-off warning cascade). After 15 seconds, the assistance system issues a yellow warning, followed by a red indicator on the instrument panel and, in addition, audible warnings at increasingly shorter intervals until outputting a continuous tone.

The Emergency Stop function is activated after 60 seconds since the start of the hands-off warning cascade without the driver having placed their hands back on the steering wheel. This initiates a speed reduction by releasing the throttle for one second. This is then followed by the speed reduction. The Emergency Stop function now takes over control of the vehicle within the system limits in order to keep it in the lane. The headlights and the hazard warning lights are activated (5 seconds before the end of the Hands-Off warning cascade) in order to warn traffic behind the vehicle and the vehicle is braked moderately to a standstill. Once the vehicle is stationary, the electric parking brake is activated and the hazard warning light system continues to flash. During intervention of the Emergency Stop function, the driver is continuously informed of the Emergency Stop and the override option by an audible, continuous beep and a visual warning on the display and can abort the process by means of a kickdown.

Active Brake Assist 5: Milestone in safety development

The unique Emergency Brake Assist 5 – ABA 5 for short – is another milestone in safety development. Presented for the first time in a touring coach in 2008, the fifth generation of Active Brake Assist, which has undergone continuous further development since then, is once again achieving a higher level of performance. For the first time, ABA 5 uses a combination of radar and camera system. Within the limits of the system, the assistance system, which is standard in TopClass and ComfortClass models, can not only perform an automated maximum full-stop braking to a standstill for stationary and moving obstacles, as is the case with the previous ABA 4 system. As the world's first emergency brake assistant for touring coaches, ABA 5 is also now able to perform automated maximum full-stop braking for moving and stationary pedestrians even up to a vehicle speed of 50 km/h.

Active Brake Assist 5 detects both moving pedestrians and suddely stopping persons. The procedure in practice: If there is a risk of a collision with a pedestrian, Active Brake Assist 5 warns the touring coach driver visually and audibly and simultaneously initiates partial braking with up to 50 percent of the maximum brake force. If the driver fails to react, emergency braking is automatically initiated until the vehicle comes to a standstill.

Numerous other new functional features also increase safety

Other innovations such as the electronic parking brake or the 360° camera system significantly increase safety in addition to function and user-friendliness. The same applies to the new, even brighter full LED headlights and the high beam assistant (see separate text on cockpit and design).