New Tool Chain for Virtual Brake Control System Validation

Abstract

The essential framework conditions fall into five main categories. The tool chain for validation of brake control systems on a hardware test bench must — be state-of-the-art and have standardised interfaces — offer the possibility of certification — represent a professional tool environment — be flexible and intuitive to operate — and enable adherence to Volkswagen-Group standards (control unit communication, test bench automation, etc.). When measured against these requirements, the existing tool chain proved to not be future proof. It can, however, provide important experience for the definition of a new, future-orientated working environment in which the driving dynamics simulation acts as a core component, but alone does not fulfil all essential requirements. Figure 2 shows the definition of a target tool chain. Open image in new window Figure 2 Functional requirement and creation of a tool chain for fully automated validation of brake control functions on a hardware-based test bench (© EFS) The requirements to be tested are maintained in the requirement management tool Doors and can be read out automatically. For example, vehicle-specific parameters shall be maintained in the requirements document and not in the test case definition. As a Group standard, Exam is the tool for test automation for the entire test bench. Odis defines the communication with the control unit. The decisive advantage when choosing software packages lies in their accountability and group-wide visibility. Should errors occur in one of these group tools, they will be quickly detected by a large user group, and handled by a support and development team of adequate capaCity. Maintenance is thus not the responsibility of the test execution team. In addition to automation, it must be possible to execute functional and software tests on the hardware test bench in parallel with development, without having to involve a testing vehicle or prototype. A suitable tool chain should enable intuitive working. Based on the premise of building the tool chain on commercial software and group-wide standard procedures, in the overall chain the question remains as to the optimal simulation tool for driving dynamics calculation. Three market-leading vehicle dynamics simulation representatives were involved in the evaluation process. Evaluation includes, in addition to catalogue value evaluations, a significant practical phase in which test systems were built using the respective simulation software. Two groups of “experienced employees” and “new employees” were assigned the task of implementing existing and new test scopes for a specific brake control function on the physical test system, with the time available to them and technical support from the manufacturer. The measured variables of time to learn the system, operability, and usability were captured as part of this exercise, within a fixed time frame of undisturbed work, Table 1. The benchmark was supplemented following intensive cost negotiations regarding financial cost, Table 1. Costs are classified from 1 to 3 (lowest to highest financial cost). Provider 3 was selected from a functional, technical, and specialist viewpoint. This enabled phase 3 of the project to begin at the end of 2015, Figure 1. Table 1 Standardised results from evaluation process of three software providers of vehicle dynamics simulation on the actual test scope catalogue of a brake control function (n.r. = not rateable, due to incomplete test bench implementation) (© EFS) Criterion Provider 1 Provider 2 Provider 3 Test creation effort 100 % 50 % 25 % Test execution duration 100 % n.r. 15 % Test migration effort 100 % n.r. 35 % Development phase testing − n.r. + Tech. Support − + + Familiarisation time − − + Operability, usability − o + Model changes effort − n.r. + Debugging − n.r. o Cost from 1 lowest-priced to 3 highest-priced provider Licences 2 1 3 Migration expenditure 3 1 1 Internal migration costs 1 2 2 Maintenance per year 3 1 2 Total costs 2 1 3