Ángel Suescun

Full-body performance animation with Sequential Inverse Kinematics

In this paper, we present an analytic-iterative Inverse Kinematics (IK) method, called Sequential IK (SIK), that reconstructs 3D human full-body movements in real time. The input data for the reconstruction is the least possible (i.e., the positions of wrists, ankles, head and pelvis) in order to be usable within a low-cost human motion capture system that would track only these six features. The performance of our approach is compared to other well-known IK methods in reconstruction quality and computation time obtaining satisfactory results for both. The paper first describes how we handle the spine and the clavicles before offering a simple joint limit model for ball-and-socket joints and a method to avoid self-collisions induced by the elbow. The second part focuses on the algorithms comparison study.

Evaluation of on-line analytic and numeric inverse kinematics approaches driven by partial vision input

Despite its central role in the constitution of a truly enactive interface, 3D interaction through human full body movement has been hindered by a number of technological and algorithmic factors. Let us mention the cumbersome magnetic equipments, or the underdetermined data set provided by less invasive video-based approaches. In the present paper, we explore the recovery of the full body posture of a standing subject in front of a stereo camera system. The 3D position of the hands, the head and the center of the trunk segment are extracted in real-time and provided to the body posture recovery algorithmic layer. We focus on the comparison between numeric and analytic inverse kinematics approaches in terms of performances and overall quality of the reconstructed body posture. Algorithmic issues arise from the very partial and noisy input and the singularity of the human standing posture. Despite stability concerns, results confirm the pertinence of this approach in this demanding context.

The Influence of Interaction Technology on the Learning of Assembly Tasks Using Virtual Reality

Rhaptic, and two configurations of the Markerless Motion Capture (Mmocap) system (with 2D or 3D tracking of hands). The fifth group was trained with a video tutorial. A post-training test carried out the day after evaluated performance in the real task. The experiment studies the efficiency and effectiveness of each interaction technology for learning the task, taking in consideration both quantitative measures (such as training time, real task performance, evolution from the virtual task to real one), and qualitative data (user feedback from a questionnaire). Results show that there were no significant differences in the final performance among the five groups. However, users trained under mouse and 2D-tracking Mmocap systems took significantly less training time than the rest of the virtual modalities. This brings out two main outcomes: (1) the perception of collisions using haptics does not increase the learning transfer of procedural tasks demanding low motor skills and (2) Mmocap-based interactions can be valid for training this kind of tasks. [DOI: 10.1115/1.4028588]

Integration of multibody systems in mechatronic simulation environments of any kind

In this paper, we describe the characteristics of a software library for multibody simulation which is compliant with a large variety of simulation environments. This software package is the result of the current needs of multibody clients, who demand far more than a traditional application able to model and analyse mechanisms. They want a tool which is highly flexible, efficient and transparent and can therefore be used to integrate multibody models in the frame of real-time multidisciplinary simulations. In order to show the good performance of this tool, its application in European project ODECOMS is presented.

Modeling of Shotcrete Application for Use in a Real‐Time Training Simulator

This article describes how simulators can provide significant advantages for training operators of concrete spraying machinery. These advantages include economic savings, the practical absence of safety risks, and environmental and educational benefits. The main challenge in developing a real-time training simulator for concrete spraying machinery lies in the modeling of shotcrete application. A novel method that models and simulates in real time is presented in this article. The three main factors that influence shotcrete sprayability are adhesion, cohesion, and rebound. Furthermore, the method presented makes it possible to spray onto additional supporting elements, which is a typical shotcrete application. The proposed method considers a wet-mix thick flow spraying process and is based on experiments that were run with a real concrete spraying machine and complemented by expert advice. A method was developed and evaluated in this paper using a user-centered methodology that resulted in realistic shotcrete application modeling that meets the needs for training machinery operators.

Kinetic Pseudo-energy History for Human Dynamic Gestures Recognition

In this paper we present a new approach, based on the kinetic status history, to automatically determine the starting and ending instants of human dynamic gestures. This method opens up the possibility to distinguish static or quasi-static poses from dynamic actions, during a real-time human motion capture. This way a more complex Human-Computer Interaction (HCI) can be attained. Along with this procedure, we also present a novel method to recognize dynamic gestures independently from the velocity with which they have been performed. The efficiency of this approach is tested with gestures captured with a triple axis accelerometer, and recognized with different statistical classifiers, obtaining satisfactory results for real-time applications.

Head Injuries due to Unrestrained Objects during Frontal Collisions

This paper evaluates the consequences of the impact of an unrestrained object against the head of vehicle occupant during a frontal crash by means of a computational head–neck biomechanical model. The correct positioning of head restraints can partially protect the rear side of the head, but there is still a significant probability of being injured. However, because head restraints are typically not properly adjusted as whiplash studies have shown, the probability of being impacted by an unrestrained object during a frontal crash is noticeably high and hence the risk of being injured is also high. In this work, head injury risk is evaluated through the Head Injury Criterion (HIC), by simulating a complete head–neck biomechanical model with realistic motion under frontal crash condition. The model developed includes all cervical vertebrae, intervertebral discs, ligaments and muscles. The model was validated against experimental data. Results have shown that the risk of severe head injury in frontal collision due to unrestrained objects cannot be neglected. The risk is directly related to the mass of the impact object, the relative velocity between the object and the head and the incorrect use of the head restraint.

A head-neck biomechanical model of a 6-year-old child for frontal crash studies

The objective of this research is the development of a detailed computational model describing the kinematic and dynamic behaviour of a 6-year-old child head-neck group in frontal crash situations without head contact. The child model was scaled down from a previous biomechanical adult head-neck group. Three validation processes were performed. Firstly, the head centre of gravity acceleration was validated against the response of the head-neck group of MADYMO® Hybrid III 6-year-old dummy during a frontal crash. Secondly, the head centre of gravity displacement was validated against the scaled response of adult volunteers during a frontal crash. Finally, the occipital condylar moment was compared against the biofidelity requirements for Hybrid III 6-year-old dummy during the pendulum calibration test. Results showed good correlation between the response of the child model and both validation subjects, the child dummy and the scaled response of adult volunteers.

Standardizing IT Systems on Public Transport: An Eco-Driving Assistance System Case Study

As urbanization increases, mobility becomes more complex and supposes a major challenge for public transportation authorities. An approach to tackle this problem is to introduce systems that ease vehicle operation and monitoring. However, these systems are hard to maintain and integrate. On this paper, a new information technology (IT) architecture is introduced. Developed by the ITxPT association, the architecture aims to improve the cost-effective implementation of the IT modules in public transport fleets. This architecture has capitalized the work of several European projects to create a solid standard ready to test on field. Finally, a use case of the introduction of an eco-driving assistance system that employs this architecture in real operation is presented.