Multibody Dynamics
There is an extremely large body of literature dealing with the modelling and simulation of multibody systems, e.g. [1–7]. The importance of multi-body systems is also recognized in robotics where different approaches have been developed taking into accou
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9.1 Introduction There is an extremely large body of literature dealing with the modelling and simulation of multibody systems, e.g. [1-7]. The importance of multi-body systems is also recognized in robotics where different approaches have been developed taking into account the control aspect as well [8,9]. The modelling of multibody systems has attracted attention in bond graph theory, too. The models are based on field multiport elements and multibonds [10--12]. In this section we describe the modelling and simulation of rigid multibody systems using the component model approach. In mechatronics, the problem is not only the mechanical part, but the complete system including the controls and the interaction with the environment as well. The general component model approach developed in this book can be applied readily to such complex systems. The bond graph approach normally leads to the representation of the multi body system with system constraints described at the velocity level, not positional [13]. This is not specific to bond graphs, but is a characteristic property of the dynamics of systems that are described by the classical Newton-Euler approach In this respect it corresponds more closely to the elegant approach of [7]. We will show that it is a viable approach not only from the modelling point of view, but also from the simulation aspect, as well. The component modelling approach enables the systematic development of the model, starting from the physical components and modelling the structure of the system. In this way the resulting model is more easily understood. Visual representation of the model helps this too. We start with planar multibody systems first and develop a component model of body dynamics. Then the basic joints-such as revolute and prismatic jointsare analysed and the corresponding models developed. It is shown on an example of a quick return mechanism how the simulation model of mechanisms can be developed systematically. The system behaviour is analysed by simulation. To show the applicability of the approach to more complicated systems, the well-known Andrews' squeezer mechanism [13] is analysed. The accuracy of the simulation results is compared to the published results [13,14]. It is shown that the simulation times and accuracy achieved are good, at least for engineering needs. As the last example of planar multibody dynamical systems, an engine torsional vibration problem is analysed. The last two sections deal with modelling of space multibody systems. An approach to modelling of such systems is described and space component models of bodies and basic joints are developed. In the last section of this chapter, the V. Dami et al., Mechatronics by Bond Graphs © Springer-Verlag Berlin Heidelberg 2003
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9 Multibody Dynamics
method and components developed are applied to the modelling and simulation of a complete robot system. A three-degree of freedom robotic manipulator is analysed. This has a wrist carrying a tool, which is pressed onto, and moved across, a wall. A hybrid forc
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