The RT-Range now measures the “time-to-impact” or “time-to-collision” as required for NHTSA’s proposed active safety tests for Forward Collision Warning Systems. NHTSA are proposing that the vehicle should warn the driver if an impact will occur within 1.5s and the new tests will be designed to test the warning system.
When the Hunter is on a collision course with the Target, the Longitudinal Time-to-collision value will be computed assuming constant relative speed between the vehicles. The Longitudinal Time-to-collision value works using the Longitudinal Range and Longitudinal Range Rate values. If the vehicles are not on a collision course (i.e. in different lanes) then it is possible to have a “dry run” with the Hunter passing the Target without colliding. The Longitudinal Time-to-collision will reduce to zero and then go negative (implying that the vehicles will no longer impact or that the collision has already occurred).
The RT-Range also computes a Lateral Time-to-collision value. Although this is not yet required, it may be useful in the future for testing systems that alert you to vehicles in your blind spot.
Both the Time-to-collision measurements are output on the CAN bus in real-time so that they can be picked up by the data acquisition system. The values can be displayed in the Real-Time Display and exported from the RT-Range Post-processing software.