CASE STUDY

JLTV
Customer

AM General

OpenECU Used to Develop Military Vehicle ABS/TCS/ESC Production System Control Software

Challenge

To develop a custom, integrated Anti-lock Braking System, Traction Control System and Electronic Stability Control system for AM General’s BRV-O, a new military light tactical wheeled vehicle platform designed to meet FMVSS 126 requirements for vehicles with a GVW over 10,000lb.  The vehicle had a high center-of-gravity, long wheel travel and large tires, which provide a challenging environment for an effective stability management system.  One of the bigger challenges was to develop the system without a vehicle being available until late in the program.

Solution

Leveraging prior knowledge and experience, Pi Innovo’s Systems Engineering team developed a clean-sheet Anti-lock Braking System with brake-based traction control, integrated into an overall vehicle stability management system. The brake control system was developed in a simulation environment before any vehicle testing was conducted. Given that ABS / TCS / ESC are safety-critical systems, Pi Innovo developed a software development and validation program based on input from an initial system-level safety analysis and through extensive failure mode and fault-tree analyses.  The resulting controls package included an extensive diagnostics suite and set of remedial actions designed to maintain the vehicle in a safe state when failure conditions are present in the system.  Working with the brake system component suppliers and the AM General BRV-O development team, Pi Innovo’s team used the OpenECU M461 rapid controls prototyping ECU and our Simulink–API model-based controls developer platform to develop custom production software.  The software was validated on Hardware-In-Loop test rigs, to control a system that operates by applying brake pressure to one or more wheels to induce a yaw-moment.  Oversteer and understeer are detected using a steering angle sensor and inertial sensors to model the driver’s intended path, and comparing that to the vehicle feedback.  The stability management system was calibrated to allow more over steer or under steer for off-road operation and for earlier or more aggressive intervention during on-road operation and to provide roll-over mitigation.

Results/Impact

The brake system successfully met all customer requirements and passed the US-Government specified sine-with-dwell performance test, a modified version of the FMVSS 126 sine-with-dwell maneuver for vehicles greater than 10,000 lbs.

The flexibility of the OpenECU platform allowed Pi Innovo’s team to implement sophisticated brake based stability algorithms on AM General’s new BRV-O lightweight tactical vehicle platform and successfully meet the target FMVSS requirements within 14 months from project inception.

Pi Innovo was able to reduce development time and costs by leveraging Hardware-In-Loop (HIL) simulation to test a majority of the controls before integration on a vehicle.  Through HIL testing, Pi Innovo simulated many of the scenarios and use cases that the integrated systems experience on the vehicle.

Project Features

Vehicle control systems engineering
Rapid controls prototyping
Custom software development
HIL testing
Validation testing

Duration

2009 to 2015