Real-time Multibody Model Research Articles

Real-Time Multibody Model-Based Heads-Up Display Unit of a Tractor

The concept of heads-up display can be used to provide augmented information onto the windshield of a tractor. The objective of this paper is to introduce a detailed real-time multibody model that is used in the design of a novel heads-up display unit of a tractor. To this end, a tractor is described using a multibody dynamics approach. A heads-up display unit is designed using a series of tasks that are associated with sets of logical conditions and instructions. These conditions and instructions, in turn, determine/design the analog and digital gauges. The gauges are linked with the virtual sensors installed at a number of locations on the tractor. In this study, the heads-up display unit includes elements, such as tachometer, speedometer, roll inclinometer, gear indicator, fuel gauge, and bucket height, tilt, and weight indicators. The effectiveness of the heads-up display unit is determined based on a goal of moving a certain amount of sand from one place to another. The results demonstrate the utility of the heads-up display unit.

Multibody-Based Piano Action: Validation of a Haptic Key

A piano key prototype actuated by a custom-made linear actuator is proposed to enhance the touch of digital pianos by reproducing the force feedback of an acoustic piano action. This paper presents the design and the validation of the haptic device. The approach exploits a multibody model to compute the action dynamics and the corresponding force on the key in real time. More specifically, a grand piano model that includes the five action bodies, its geometry and the specific force laws, is computed in the haptic device. A presizing step along with Finite Element Method (FEM) analysis produced an especially made actuator satisfying the design requirements, in particular the highly dynamic nature of the force to be transmitted. Force peaks, up to 50 (N) in less than 20 (ms), are reachable with low power consumption. Compared to previous solutions: (i) the key physical characteristics are preserved; (ii) the feedback is based on a real-time multibody model that is easily configurable and interchangeable; (iii) an experimental validation of the actuator within the prototype is developed and demonstrates its feasibility. The results confirm that the voice coil can produce suitable haptic feedback. In particular, rendering a grand piano action within the device shows promising haptic force profiles.

Deformable Terrain Model for the Real-Time Multibody Simulation of a Tractor With a Hydraulically Driven Front-Loader

A real-time multibody model of an off-road vehicle can be used to analyze the dynamics of tasks, such as loading and/or transferring material from deformable ground. This analysis requires an accurate description of the mechanics, hydraulic actuators, and the terrain. The objective of this paper is to introduce a novel, real-time capable, deformable terrain/soil model that can interact with the mechanics of a multibody system model and the dynamics of a hydraulics model. To this end, a tractor is modeled by using a semi-recursive multibody formulation based on velocity transformation. The hydraulic actuation of the tractor's front-loader is modeled by using the lumped fluid theory. The tractor loads and transfers sand material from a deformable sand field (the ground), which is modeled by combining mesh-based and particle-based soil representation approaches for the real-time simulation of soil deformation. The work cycle of the tractor model follows a 3D maneuver that is used to load and transfer sand material. During the digging and dumping operations, the static sand field is converted into sand particles and vice versa respectively. For the presented work cycle, the real-time capability of the system is analyzed and determined. Furthermore, the dynamic actuator forces in the hydraulic cylinders are compared with the static actuator forces. The introduced real-time capable tractor simulation model can be utilized in product development and other product processes.

Validation of a Real-Time Multibody Model for an X-by-Wire Vehicle Prototype Through Field Testing

This research focuses on the experimental validation of a real-time vehicle multibody (MB) model whose bodies are considered rigid. For this purpose, a vehicle prototype has been built and automated in order to repeat reference maneuvers. Numerous sensors on the prototype gather the most relevant magnitudes of the vehicle motion. Two low speed maneuvers involving the longitudinal and lateral vehicle dynamics have been repeated multiple times in a test area. Then, a real-time MB model of the vehicle prototype has been self-developed as well as a simulation environment that includes a true graphical environment, a true road profile, and collision detection. Subsystems like brakes and tires have also been modeled. Both test maneuvers have been simulated with the MB model in the simulation environment using inputs measured experimentally. Selected simulation variables have been compared to their experimental counterparts provided with a confidence interval (IC) that characterizes the field testing (FT) process errors. The results of the comparisons show good correlation between simulation predictions and experimental data, thus allowing to extract useful guidelines to build accurate real-time vehicle MB models. In this way, the present work aims to contribute to the scarce literature on vehicle complete validation studies.

Objective and subjective evaluation of an advanced motorcycle riding simulator

PurposesThis paper outlines the characteristics of a top-of-the range motorcycle simulator designed and built at the University of Padua over a period of several years last years; it consists of a motorcycle mock-up with functional throttle, brakes, clutch and gearlever mounted on a five ‘degrees of freedom’ platform, a real-time multibody model of the motorcycle and an audio and visual systems. The applications of the simulator are to test devices such as ABS, traction control and other ARAS in a controlled, safe environment, to study riders’ behaviour and to train them. The aim is to find a procedure to validate the behaviour of a Motorcycle Riding Simulator with a real PTWs.MethodsAn innovative procedure for the objective and subjective validation of motorcycle simulators has been developed and implemented, in order to be able to apply the results obtained on the simulator to the real world.ResultsThe evaluation of objective and subjective data collected shows that the proposed simulator is adequate for handling tests. The proposed method is suitable to be extended to vehicle simulator in general.ConclusionsThe development work done by University of Padova provides an innovative and reliable tool for the validation of a motorcycle riding simulator.