Robotran

Bombardier Iltis vehicle

The Bombardier Iltis vehicle was published in 1993 in the journal of the IAVSD [1] . This system allows to comparison of different modelling approaches and implementations with identical inputs. The benchmark provides all required data’s (dimensional and dynamical) and the tire-road contact law to be used.

The benchmark asks for the computation of an equilibrium state, of the modal analysis and of multiples dynamic simulations. The dynamic simulations include non-flat road profiles and various steering manoeuvrers.

keywords : Vehicle, Dynamic, Equilibrium, Modal, Contact

Model description

The model of the Bobmardier Iltis vehicle consists in:

22 bodies;
2 kinematic loops per wheel;
Forces elements for the suspensions (leaf springs, bumpers and shock absorbers);
A CALSPAN tyre force model;

Suspension of the Bombardier Iltis — Elements of the suspension

Benchmark contents

The benchmark ask for the following results:

Static equilibrium;
Eigenvalue at constant speed;
Dynamic simulation on a bump road profile;
Dynamic simulation of an anti-phase (left and right sides) bump road profile;
Dynamic simulation of steering manoeuvrers.

Results

The simulations results obtained with Robotran matches the solutions obtained in the benchmark by several software. Some of the results are shown below to illustrate the matches. Results from FASIM, MEDYNA, NEWEUL and SIMPACK come from [1].

Static Equilibrium

Interaction	Dim.	ROBOTRAN	FASIM	MEDYNA	NEWEUL	SIMPACK
cabin: vert. displacement	mm	-7.083	-7.230	-7.078	-7.100	-7.094
cabin: pitch angle	°	0.1465	0.1767	0.1438	0.1509	0.1468
right front tyre	N	-3831.31	-3831.46	-3829.23	-3534.63	-3831.32
shock absorber right front	N	-335.29	-335.24	-334.67	-336.54	-335.51
leaf spring right front (force element)	N	-3068.62	-3068.5	-3067.13	-3071.13	-3069.15
leaf spring right front (rod)	N	-1408.51	-1404.20	-1372.19	-1406.13	-1404.68

Eigenvalues

In the benchmark the eigenvalues are computed either with linear tyre parameters and with the complete CALSPAN tyre model (linearization is done by the software). Only the results with the complete CALSPAN model are illustrated below. The results of Robotran are in bold, the comparison is done with SIMPACK resutls..

Mode nb.	Description	Freq. (Hz)	Damping ratio (%)	Freq. (Hz)	Damping ratio (%)
7/8	cabin lateral / roll out of phase	1.44	37.57	0.91	69.38
9/10	cabin pitch	1.28	44.34	1.63	38.75
15/16	Wheel hop: cabin bounce	12.84	34.53	13.88	34.29

Dynamic simulations

Find below some simulations results obtained with ROBOTRAN. Refers to [1] to get the results obtained in the reference benchmark.

In-phase cosine bump with speed v = 5 m/s , pitch angle

Anti-phase cosine bump with speed v = 10 m/s , roll angle

Ramp-to-step steer with rack displacement 2mm, yaw rate

Sinusoidal steering manoeuvre with 1Hz Frequency, yaw rate

References

[1] Frik, Leister & Schwartz (1993) Simulation of the IAVSD Road Vehicle Benchmark Bombardier Iltis with FASIM, MEDYNA, NEWEUL and SIMPACK, Vehicle System Dynamics, 22:sup1, 215-253, DOI: 10.1080/00423119308969496