Real-time simulators have become more popular in the field of user training. This is due to the possibility to give basic training and knowledge of machines and their operation environment to the operator even when the machine is not actually present. The use of simulators instead of actual machines has several advantages. First of all, the available machine capacity is not tied to training and can be used in productive work. Secondly, using a simulator helps to avoid accidents that may occur using real machines. Using a simulator also enables different environmental aspects, such as lighting conditions, fog, wind, and so on, to be taken into account in the training of all operators alike. Real-time training simulators are complicated machine systems, which consist of a user interface, an I/O-system, a real-time simulation model describing the dynamics of the machine in question and its connections to the environment, a visualization of the operational environment, and a possible motion platform. The user interface is usually taken directly from the simulated machine. Consequently, the user has the possibility to become familiar with the operating interface in an early phase of training. In this article, the development of a gantry crane operator-training simulator, including all the earlier mentioned components, is presented. The aim of this article is to present an example of methods used in the development of the separate areas of a training simulator.

This article presents the modelling principles of the joint constraints for flexible multibody systems. The joints are composed using three basic constraint primitives which are derived including their first and second time derivatives as well as the components of the Jacobian matrix. The description of the derived components of constraint primitives can be used to develop a library of kinematic joints to use in multibody codes. In this study, the equations of motion are defined using generalized Newton-Euler equations where the deformations are accounted for by using the floating frame of reference formulation with modal coordinates. The deformation modes used in the floating frame of reference formulation are obtained from the finite-element analysis by employing the lumped mass matrix. Dynamic analysis of a mechanism consisting of rigid and flexible bodies is used to illustrate the validity of the constraint formulation.

A real-time simulator for a tree harvester has been developed for training in more effective vehicle and cutter operation and tree management. The equations of motion of the constrained mechanical system of the tree harvester are expressed using a recursive formulation. The hydraulic actuator modelling of the harvester is based on lumped fluid theory, in which the hydraulic circuit is divided into discrete volumes where pressures are assumed to be distributed equally, while pressure wave propagation in pipes and hoses is assumed to be negligible. For modelling purposes, valves are broken up into a number of adjustable restrictors, which can be modelled separately. The contact model used comprises two parts: collision detection and response. Collision detection identifies whether, when and where moving bodies may come in contact. Collision response prevents penetration when contact occurs and identifies how it should behave after collision. A penalty method is used in this study to establish object collision events. The major achievement of this study is combining these three modelling methods in the application of a real-time simulator.

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