IMPROVED HYBRID COMPUTER VEHICLE HANDLING PROGRAM (IHVHP)

The Improved Hybrid Computer Vehicle Handling Program (IHVHP) is an extension of the Hybrid Computer Handling Program (HVHP) described in DOT-HS-802-059, Jul 1976. The computing tasks have been redistributed between the analog and digital computers. Many of the simplifications that existed in the HVHP have been removed. The equations of motion for the sprung and unsprung masses of a vehicle have been expanded to include higher order terms and large pitch and roll angles. Numerous geometric and kinematic calculations have been modified to include large pitch and roll angles. The hybrid computer simulation for vehicle handling studies has been in use for 6 years and can simulate (a) independent front and rear axles, (b) independent front with solid rear axle, (c) independent front and solid rear axle with dual rear tires, (d) solid front and rear axles, and (e) solid front and rear axles with dual rear tires. For validation purposes, braking, steering, and combinations of braking and steering were put into the simulated mathematical model; the simulation time histories were then compared to fullscale test data. The hybrid vehicle handling program can be used for general studies of vehicle dynamics. Performance of the National Highway Traffic Safety Administration (NHTSA) standard passenger car Vehicle Handling Test Procedures (VHTP's) and calculation of the associated performance comparison variables (PCV's) are simulation options. A special interactive user's interface allows program use by vehicle engineers as well as by computer specialists.