Evolution of Brake Controls to Motion Systems

Brake systems are becoming increasingly intelligent so they can meet the future needs and requirements of automated driving and electrification. First implementations will happen in next-generation vehicles with a modified architecture. This functional requires a profound understanding of new vehicle architectures in order to combine uncompromising safety and sustainability in future brake systems. In the long-term, brake systems become modular and distributed. Continental is therefore in the middle of the driver seat. Due to excellent collaboration with many automobile manufacturers (OEMs) we will be able to shape the future of brakes.

Vehicles are currently being reconceived. Global megatrends are driving these efforts: Vehicle architecture is changing with the electrification of the powertrain and the growing capabilities of automated driving (AD). Digitalization and connectivity are fundamentally realigning the electrical and electronic architecture (E/E architecture) of vehicles, which is increasingly based on software – because it’s the software which, in future, will define the character of cars and the driving experience! Bytes take the place of horsepower. Apps and services are expanding the car into an immersive experience that’s steadily becoming safer and more comfortable.

Future Brake System (FBS) is here

With digitalization and connectivity, electric drives and AD capabilities, brake systems must therefore fulfill a broad number of additional tasks. To this end, Continental, as a long-standing, globally proven brake system specialist, is developing future brake system technologies: Future Brake System (FBS). In the following, we outline the journey into the future of brakes, and an innovation roadmap to a far-reaching, step-by-step transformation.

Brake-by-wire with hydraulic fall-back

_{Future Brake System Level 0}

Brake-by-wire-expertise for about 20 years
One box solution in series since 2016
Recuperation in electric vehicles
Highly Automated Driving supported by backup unit "HBE"

Continental has developed the MK C2, a modularized and scalable system generation.

Explore our MK C2 Products

As a more advanced development, it is even more compact, lighter and more cost-effective and, thanks to Multi-Logic, has performance characteristics superior to those of the MK C1. With Multi-Logic, the MK C2 features two printed circuit boards and two processors that can be used to uphold more functions in the event of a fault. This allows, for example, that the parking brake can be actuated redundantly. This makes it possible to dispense with a highly expensive mechanical transmission lock for immobilizing the vehicle. Owing to its benefits, the MK C2 evolutionary stage will form the basis for a Future Brake System (FBS).

True brake-by-wire technology

_{Future Brake System Level 1}

Building on the long experience gained with tried-and-tested electromechanical actuation, the transition to a complete brake-by-wire system can now follow. To this end, Continental has developed the MK C2D concept, a modularized and scalable system generation that consists of two independent actuators.

MK C2 brake-by-wire with electronic brake pedal

Gateway to Future Brake System
Enabler for rolling chassis
Packaging flexibility
Supports Automated Driving SAE level 3 up

The MK C2D (D=distributed) can be used as before with a mechanical pedal – MK C2D mP (mP=mechanical pedal) (an FBS 0 system with hydraulic fallback mode by the driver and brake pedal). But as well with an electronic brake pedal – MK C2D eP (eP=electronic pedal). In this case, like in highly automated driving (HAD) mode, the second actuator takes over in case of a fallback situation instead of the driver’s foot.

The MK C2D system generation is designed for AD in accordance with SAE Level 3 or higher. The platform uses existing components that have already proven themselves in the MK C2.

The complete separation of pedal and pressure generation without fallback mode provides a huge advantage for integration, which is characteristic of real brake-by-wire systems: The brake system no longer has to be mounted directly at a specific location on the firewall in front of the driver to enable mechanical fallback. Instead, a FBS 1 with electronic pedal supports new vehicle concepts involving different vehicle interiors and dimensions, such as the skateboard chassis of electrified vehicles, on which various bodies can be mounted.

The brakes become “semi-dry”

_{Future Brake System Level 2}

In today’s brake systems, as well as with FBS 0 and FBS 1 solutions, pressure generation is still fully integrated into the brake system unit. The hydraulics (i.e. the “wet” part of the brake system) transmit the force to the brake calipers of the disk brakes or the drum brakes.

Full brake-by-wire, semi-dry (rear axle dry)

MK C2
Modular approach
Vehicle assembly simplified for rear axle

The MK C2D (D = distributed) can be used as before with a mechanical pedal – MK C2D mP (mP=mechanical pedal) (an FBS 0 system with hydraulic fallback mode by the driver and brake pedal). But as well with an electronic brake pedal – MK C2D eP (eP=electronic pedal). In this case, like in highly automated driving (HAD) mode, the second actuator takes over in case of a fallback situation instead of the driver’s foot.

The MK C2D system generation is designed for AD in accordance with SAE Level 3 or higher. The platform uses existing components that have already proven themselves in the MK C2.

The complete separation of pedal and pressure generation without fallback mode provides a huge advantage for integration, which is characteristic of real brake-by-wire systems: The brake system no longer has to be mounted directly at a specific location on the firewall in front of the driver to enable mechanical fallback. Instead, a FBS 1 with electronic pedal supports new vehicle concepts involving different vehicle interiors and dimensions, such as the skateboard chassis of electrified vehicles, on which various bodies can be mounted.

The brake can be broken up into modules

_{Future Brake System Level 3}

In a very long-term view, the hydraulic system could be eliminated completely: To achieve this, all four wheel brakes could be actuated electromechanically and would thus be completely “dry”. The current focus on pressure generation and modulation with appropriate control intelligence would then no longer be necessary.

Full brake-by-wire with electronic brake pedal: dry & modular

Electric actuation (dry)
Dry caliper or drum brakes
Scalable & modular hardware
Portable software
Functional software on HPCs for safety redundancy

An FBS 3 brake system consists of the four dry wheel brakes (calipers or drums) and a series of software function blocks which, for reasons of safety and redundancy, can run on several of the existing High-performance Computers (HPC) with integrated Wheel Control Units providing the redundancy required for safety. The dry brakes enable independent control of braking forces on each wheel, optimizing driving dynamics.

To make this long-term transformation to FBS 3 possible at all, the individual functions of a brake system must be encapsulated as stand-alone products in modular, validated and proven software blocks that can be integrated into various vehicles thanks to standardized interfaces based on the principle of re-use.

Conclusion

Motion functions remain the cornerstone of active driving safety. Nowhere is that clearer than in brake systems. At the same time, however, the general conditions for motion control functions are changing very significantly due to the new E/E architecture and new vehicle capabilities such as AD. Here, Continental is actively seeking to exchange ideas with vehicle manufacturers in order to shape the further development of brake systems in dialog with them. This is all very important because many of the advantages of future systems will be less significant for brake functions than for the vehicles themselves.