Hardware architecture L4

 

The hardware architecture comprises the network of control units, the redundant onboard network and the steering and braking systems. It forms the basis for executing the L4 automation function in the vehicles and on the HIL test bench.

 
Work focuses

ECU / computer topology:
The algorithms used for automated driving functions are extremely computationally intensive and therefore require very powerful hardware components that must also have a high level of integrity. For the development and evaluation of these algorithms, the first step is to rely on a high-performance and scalable computer architecture that enables fast development cycles. In the second step, the functions are integrated into control units that have a high level of hardware integrity and also meet the requirements for future series production.

 

Vehicle and interface design:
Based on the hardware architecture concept, test vehicles are built in various expansion stages. For this purpose, the hardware and software interfaces of the series vehicle are expanded and additional hardware components are integrated. A distinction is made between test vehicles for component testing, function development and demonstration. Component test vehicles are used to test individual components such as the onboard network, steering or braking system. Function development vehicles contain highly flexible control units and therefore allow rapid function development and validation. In order to display the automation status of the vehicles to the outside world, suitable solutions are considered and prototypically integrated into one of the test vehicles.

 

Onboard Network
To enable all control units, sensors and actuators in the vehicle to function, it must be ensured that they are supplied with sufficient electrical power at all times. In this work package, the basic requirements for the electrical power supply are compiled and a system for the highly available provision of energy is developed. The existing onboard network of the reference vehicle is adapted to the requirements of the planned level 4 functionality in several successive steps. This includes the integration of the redundant power supply and the intelligent power distributor, which can identify and isolate faults in the vehicle electrical system if necessary. This ensures that the safety-relevant vehicle functions are supplied with energy in a fault-tolerant manner. Various simulations, vehicle measurements and the corresponding integration of measurement technology complete this WP. The vehicle measurements can be used to generate, measure and evaluate various states and specific faults in the on-board power supply system in its installed state under real driving conditions.

 

Steering system:
A prerequisite for the realization of an automated guided truck and the prototypical development and representation of the lateral guidance function is the possibility of actively specifying a wheel steering angle or output shaft angle. A corresponding existing steering system will be integrated into a vehicle, and any necessary adjustments will be made in coordination between the project partners. After installation in the demonstrator, the software interfaces are developed and approved for operation on public roads with a safety driver. The realization for a driverless system places significantly higher and new demands on the target steering system and the system network interaction, as the system reaction must be considered after every possible initial error and a degradation concept must be developed for this case.

 

Braking system
In order to operate an autonomously driving truck safely, a redundant braking system is required that functions safely and reliably under all given conditions. The central task is to fulfill the safety concepts required for this application while at the same time complying with the driving dynamics requirements. The chosen solution approach is scalable. This also includes the possibility of incorporating the parking brake as a tertiary braking system as an additional fallback level. The same applies to the “steer-by-brake” function, which can be seen as a tertiary level to the project partner's redundant steering system. As not all components have to be newly developed and some of the sensors and actuators are used jointly by the primary and secondary systems, existing vehicle concepts can be retrofitted with little effort.