Sergio Casas

Towards a simulation-based tuning of motion cueing algorithms

Abstract This paper deals with the problem of finding the best values for the parameters of Motion Cueing Algorithms (MCA). MCA are responsible for controlling the movements of robotic motion platforms used to generate the gravito-inertial cues of vehicle simulators. The values of their multiple parameters, or coefficients, are hard to establish and they dramatically change the behaviour of MCA. The problem has been traditionally addressed in a subjective, partially non-systematic, iterative, time-consuming way, by seeking pilot/driver feedback on the generated motion cues. The aim of this paper is to introduce a different approach to solve the problem of MCA tuning, by making use of a simulated motion platform; a series of (human-based) objective metrics relating to the performance of MCA are measured using this simulated device. This simulation-based approach allows for automatic tuning of the MCA, by using a genetic algorithm that is proposed to analyse the results obtained from multiple simulations of the MCA with different parameters. This algorithm is designed to efficiently optimize the simulated MCA parameter space. The proposed solution is assessed with the classical washout MCA, performing a series of tests to validate the correctness of this approach and the suitability of the proposed method to the solution of the MCA tuning problem. Results show that this approach can be an alternative to the traditional subjective tuning method in certain situations, mainly because it provides suitable values for the MCA parameters in a shorter time period, albeit subjective tuning is preferred when time to perform the MCA tuning is not an issue.

Motion-cuing algorithms: characterization of users' perception.

Objective: The aim of this study was to characterize the human response to motion-cuing algorithms (MCAs) by comparing users’ perception to several proposed objective indicators. Background: Other researchers have proposed several MCAs, but few improvements have been achieved lately. One of the reasons for this lack of progress is that fair comparisons between different algorithms are hard to achieve, for their evaluation needs to be performed with humans and the tuning process is slow. Method: This characterization is performed by means of a comparison of the subjective perception of vehicle simulation users (90 participants) against several proposed objective indicators that try to measure MCA performance. Two motion platforms (3 and 6 degrees of freedom [DoF]) and two vehicle simulators (a driving simulator and a speedboat simulator) were tested using the classical washout algorithm, considered to be the main reference in MCA literature. Results: Results show that users are more sensitive to correlation and delay with respect to the expected motion rather than its magnitude and that specific force is more of a factor than angular speed in the driving simulator. The opposite happens in the speedboat simulator. Conclusions: Human drivers’ reaction to MCA is mainly characterized by the normalized Pearson correlation between output and input signals of the algorithm. This finding validates the main MCA strategy that consists of downscaling the signals and slightly distorting their frequency spectrum. The 6-DoF simulator is perceived as a modest improvement of the 3-DoF platform. Applications: These results set the basis for future automatic tuning, evaluation, and comparison of MCA in motion platforms.

Towards an extensible simulator of real motion platforms

Abstract The limitations of a real motion platform will not normally be discovered until it is completely built and tested. Late identification of its limitations imposes the necessity of a redesign of the motion platform. This, in turn, incurs important and significant economic costs for the manufacturer. Note that any change in the original design of the motion platform requires an investment in resources, money and time in order to perform the re-design of the platform. The main contribution of this paper is to address this problem by creating a virtual motion platform (VMP). This virtual motion platform is a computer-based simulation of a real motion platform which produces the same outputs as the real platform when it receives the same inputs. The VMP has been designed to easily replace the real platform in order to avoid damage to the real system, avoid the potential for human injuries and reduce costs, among other advantages. The model is extensible, enabling the simulation of different kinds of real motion platforms in real-time. The VMP has been validated against a real system implementation. This prototype has been validated against two real motion platforms that we have in our labs: a T3R3 (6DoF) and a T1R2 (3DoF) platform. Extensive empirical tests have been performed and the results show that the VPM exhibits a deviation of less than 3% with respect to the real motion platform, which is a really reasonable result considering the complexity of the simulation. We have also demonstrated that our simulation is capable of running faster than real-time being able to perform batch simulations on many different design iterations.

Motion Cueing Algorithms: A Review: Algorithms, Evaluation and Tuning

Robotic motion platforms are commonly used in motion-based vehicle simulation. However, the reproduction of realistic accelerations within a reduced workspace is a major challenge. Thus, high-level control strategies commonly referred to as motion cueing algorithms MCA are required to convert the simulated vehicle physical state into actual motion for the motion platform. This paper reviews the most important strategies for the generation of motion cues in simulators, listing the advantages and drawbacks of the different solutions. The motion cueing problem, a general scheme and the four most common approaches-classical washout, adaptive washout, optimal control and model predictive control-are presented. The existing surveys of the state-of-the-art on motion cueing are usually limited to list the MCA or to a particular vehicle application. In this work, a comprehensive vehicle-agnostic review is presented. Moreover, evaluation and tuning of MCA are also considered, classifying the different methods, and providing examples of each class.

An Augmented Reality (AR) CAD System at Construction Sites

Augmented Reality (AR) technologies allow computer-generated content to be superimposed over a live camera view of the real world. Although AR is still a very promising technology, currently only a few commercial applications for industrial purposes exploit the potential of adding contextual content to real scenarios. Most of AR applications are oriented to fields such as education or entertainment, where the requirements in terms of repeatability, fault tolerance, reliability and safety are low. Different visualization devices, tracking methods and interaction techniques are described in the literature, establishing a classification between Indoor and Outdoor AR systems. On the one hand, the most common AR developments correspond to Indoor AR systems where environment conditions can be easily controlled. In these systems, AR applications have been oriented traditionally to the visualization of 3D models using markers. On the other hand, outdoor AR developments must face additional difficulties such as the variation on lighting conditions, moving or new objects within the scene, large scale tracking, etc... which hinder the development of new systems in real scenarios.

Entertainment virtual reality system for simulation of spaceflights over the surface of the planet Mars

In recent years Virtual Reality technologies have enabled astronomers to recreate and explore three dimensional structures of the Universe for scientific purposes. Mars, due to its scientific interest,has been the focal point of numerous research projects using these technologies, however, none of these virtual reality tools have been developed specifically for entertainment purposes.The focus of this paper is to present MarsVR, as an entertainment research project that educates people on the topography and orography of the planet Mars from the perspective of popular science. Some projects have been designed MarsVR for entertainment purposes and include the latest advances in 3D real time applications. However, these applications have underestimated the relevant data necessary for simulating the planet Mars as an interactive virtual environment.

A Multi-Projector Calibration Method for Virtual Reality Simulators with Analytically Defined Screens

The geometric calibration of projectors is a demanding task, particularly for the industry of virtual reality simulators. Different methods have been developed during the last decades to retrieve the intrinsic and extrinsic parameters of projectors, most of them being based on planar homographies and some requiring an extended calibration process. The aim of our research work is to design a fast and user-friendly method to provide multi-projector calibration on analytically defined screens, where a sample is shown for a virtual reality Formula 1 simulator that has a cylindrical screen. The proposed method results from the combination of surveying, photogrammetry and image processing approaches, and has been designed by considering the spatial restrictions of virtual reality simulators. The method has been validated from a mathematical point of view, and the complete system—which is currently installed in a shopping mall in Spain—has been tested by different users.

A particle swarm approach for tuning washout algorithms in vehicle simulators

Abstract The MCA tuning problem involves finding the most appropriate values for the parameters (or coefficients) of Motion Cueing Algorithms (MCA), also known as washout algorithms. These algorithms are designed to control the movements of the robotic mechanisms, referred to as motion platforms, employed to generate inertial cues in vehicle simulators. This problem can be approached in several different ways. The traditional approach is to perform a manual pilot-in-the-loop subjective tuning, using the opinion of several pilots/drivers to guide the process. A more systematic approach is to use optimization techniques to explore the vast parameter space of the MCA, using objective motion fidelity indicators, so that the process can be automated. A genetic algorithm (GA) has been recently proposed to perform this process, with promising results. Following this approach, this paper proposes applying Particle Swarm Optimization (PSO) to solve the MCA tuning problem. The PSO-based proposed solution is assessed using the classical washout MCA, comparing its performance, convergence and correctness against the GA-based solution. Results show that a PSO-based tuning of MCA can provide better results and converges faster than a GA-based one. In addition, PSO is easier to set-up than GA, since only one parameter of the optimization algorithm itself (the number of particles) needs to be set-up, instead of a minimum of four in the case of the GA.

A Hybrid Virtual-Augmented Serious Game to Improve Driving Safety Awareness.

The use of 3D virtual content and Augmented Reality (AR) in certain applications allows designing tools and serious games that are more attractive to the potential users. Focusing on the area of learning and education, these technologies can be adapted to the requirements of the application that needs to be developed, to the available devices on which they are expected to run and also to the learning content. However, in most applications only a single interaction paradigm and a single visualization mode is used, restricting the potential benefits of the system. In this paper, we propose a software application designed to improve driving safety awareness and learning for both adults and children, in which we combine different interaction and visualization modes. The application is shaped as a hybrid virtual-augmented “Game of the Goose” in which AR, tactile interaction and 3D virtual content are brought to the user in a combined but meaningful way. The combination of these different interaction paradigms creates an educational tool which is much more intuitive and engaging. In this serious game, multiple players/users can participate simultaneously and players obtain, on the one hand, an intuitive interaction, simple and realistic based on AR and, on the other hand, an increase in the sense of immersion by means of virtual content, for a given set of driving-related situations. This provides a much more tailored learning system, making the users focus in the given driving situations. The paper describes the objectives set in the development of the application, the design and implementation decisions taken and a comprehensive but preliminary assessment performed with 285 users which provides satisfactory and promising results.

ROMOT: A Robotic 3D-Movie Theater Allowing Interaction and Multimodal Experiences

In this paper we introduce ROMOT, a RObotic 3D-MOvie Theater. ROMOT is built with a robotic motion platform, includes multimodal devices and supports audience-film interaction. Differently from other similar systems, ROMOT is highly versatile as it can support different setups, integrated hardware and contents. Regarding to the setups, here we present a first-person movie, a mixed reality environment, a virtual reality interactive environment and an augmented reality mirror-based scene. Regarding to integrated hardware, the system currently integrates a variety of devices and displays that allow audiences to see, hear, smell, touch and feel the movement, all synchronized with the filmic experience. Finally, regarding to contents, here we present some samples related to driving safety and, in the discussion section, we theorize about the expansion of ROMOT for love and sex-related interactive movies.