Roll Center Migration Study

In Summer 2019 I interned at CU-ICAR in Greenville, SC as part of a future development program for the Clemson Formula SAE Team. One of the simulations I developed was this Roll Center Migration Study. See CU-ICAR Internship for more information about the other two simulations I developed in the internship!

The roll center of a vehicle is the force coupling point at which the unsprung and sprung masses react. An oversimplification of the idea with roll centers is that you want to minimize this point’s movement as much as possible to increase the vehicle’s performance. To do this I created a two-dimensional representation of the vehicle’s front view swing arm (FVSA) geometry in MATLAB. (See the below figure “Static Car - FVSA Plane”. To reduce the complexity of the model I modeled the front and rear suspensions as two separate programs, which means the front suspension cannot affect the rear and vice versa. Given inputs such as chassis width, kingpin inclination angle, scrub radius, track width, static roll center height, and camber change rate the program first calculates the 2-D static representation of the geometry.

After the initial 2-D static calculation, the program places the suspension in its maximum heave and maximum roll modes and calculates the roll centers for each mode.

The result of this is the ability to study how the suspension’s roll center migrates as it exhibits different vehicle attitudes. To take it one step further, I allowed modeFrontier to vary several parameters in hopes to find the suspension geometry which has the smallest roll center migration. The roll center of the 2018 Clemson FSAE car, which finished 18th at FSAE Michigan 2019, migrates roughly 5” at the maximum roll. With this program, we’ve been able to make the 2020 Clemson FSAE car’s roll center migrate 0.2” at the maximum roll.