Lap Time Simulation
Why do we want to use Simulation?
- Able to eliminate run to run variations due to tire wear, track surface changes, weather, etc.
- Able to explore more combinations of inputs in less time and at a lower cost.
Hundreds or even thousands of input combinations can be solved. Track test then used to validate selected model solutions.
- Able to isolate individual variables and explore interactions between inputs.
Often any adjustment on the car influences more than one parameter; Anti-dive changes caster, Camber influences roll center height.
- Setups can be explored outside the physically available adjustment ranges.
- Optimization Routines and DOE techniques can be utilized to automate execution of simulation runs and
focus on the beneficial regions of the solution space.
Types of Simulations, Differences, Pros and Cons
- Quazi-Static Solvers: Lts, Lap Sim, Race Sim
Fast Solution, Able to find optimal lap, minimum set-up
- Lumped Parameter Dynamic Solvers: Car Sim, Handsim
Model Higher Freq Events, Transient Maneuvers, Shocks
- Multi-Body Solutions: Adams, Dads
Includes Interactions between components
How Does Simulation Work? (Quazi-Static)
- Divide track into finite segments
- Solve a force balance at each segment
- Determine max speed segment can be traversed
- Adjust speed to be compatible with adjacent segments; Define corners by segments with
minimum speed in region. Work away from adjacent corners, accelerating forward in time
and braking backward in time until the two speed traces meet.
- Examples: Lts, Bosch LapSim, RaceSim
What can be Learned from Simulation?
- Simplest Function is to Optimize Gear Ratios
- Select Best Power/Weight/Displacement Combination for the Class
- Evaluate best balance between Downforce and Drag
- Investigate balance of any parameters which require a compromise:
- Track Width vs. Drag
- Weight Distribution; Front / Rear, Left / Right
- Engine Low Speed Torque vs. Peak Power
- Downshift for more torque or No Shift to eliminate power interruption
- Investigate How Suspension Setups Influence Handling Balance
- Interactions between: Anti-dive, Anti-Squat, Roll-Center Hts, Ride and Roll rates during corner entry, center and exit.
- Influence of CG Height
- Evaluate Cost / Benefit Relationships
- Adding Chassis Stiffness incurs a Weight and likely CG penalty
- Adding Downforce creates a Drag penalty