SAE J3081:2020 pdf free
SAE J3081:2020 pdf free.Heavy Vehicle Controls Prioritization and Conflict Resolution
Care has been taken in the design of these systems to achieve acceptable operation while avoiding the addition of costly redundancy. In general, the goal is to bring the vehicle to a controlled stop, out of harm’s way, in the event of failure of a significant control system component. At least in North America, the goal has not been to provide redundancy that would permit mission completion.
For example, in case of a stuck accelerator or governor, the operator can operate the clutch and/or shift to neutral while applying the brakes if necessary. The brake system is split front rear so that complete loss of braking capability is unlikely.The steering system is possibly the most critical control system. It is for this reason that significant effort is put into assuring the robustness and reliability of the mechanical components used within this system.
As these drive- by-wire systems are being engineered, care is being taken to assure that the new systems perform in a manner at least as acceptable in their operation as the prior mechanical systems. However, there is a need for constant vigilance to assess the performance of advanced control systems that provide features not previously available on commercial vehicles. For example, automatic traction control, electronically controlled transmissions, adaptive cruise control, and hybrid systems technology.
The SAE J1939 technical report as used with CAN2.0b provides for well thought out control message prioritization. This assures that when timing is a consideration, higher priority messages will be transmitted preferentially over lower priority messages. However, in cases where multiple data links are used, it is possible for conflicting messages to be received essentially simultaneously from different networks. In all cases, intelligent control strategy must be used within the system responsible for vehicle control to assure acceptable operation regardless of the data link configuration.SAE J3081 pdf free download.
