Modeling and Control of Large Flexible Frame Vehicles Using Bond Graphs

Large vehicles such as buses and trucks suffer from a dynamic resonance problem due to flexure of the vehicle frame. This type of vibration is called “beaming”. Unlike smaller, (relatively) stiffer automobiles, this flexural vibration occurs in these large vehicles at a frequency very close to the wheel-hop frequency and body motion frequencies, and thus is excited easily by typical roadway inputs. The effect of beaming on ride quality differs from one vehicle type to another due to the mounting of the passenger compartment to the frame.

A model that provides insight into the beaming problem is formulated using bond graphs. Bond graphs allow coupling of lumped dynamic effects with the distributed dynamics of the frame, and they permit virtually automated computer coding so that different vehicle types can be simulated using basically the same model. The model utility is demonstrated for some simple automatic control strategies aimed at controlling beaming.