Abstract: Bond graph modeling for linear actuator revolute joint mechanism which uses Lagrange approach or stiff compliance approach with new elements inserted causes stiff equation problems， and causality in bond graph is not classified and modularized. A causality classification method is proposed for modeling with this kind of mechanism. Classifications for elements are classified as main-body， cylinder and lever type by analysis of element bond graphs and connection patterns， and joints are classified as root， pusher， pushed and load type to maintain the original causal link. Causality determination principles are proposed by these definitions to make modeling orderliness. An excavator mechanism modeling and simulation demonstration proved that proposed method is suitable for mechanism cases of earthmoving vehicles.

Key words: linear actuator revolute joint mechanism, classification, bond graph method, causality, earthmoving vehicles