The contribution of visual and proprioceptive information to the perception of leaning in a dynamic motorcycle simulator

Compared with driving or flight simulation, little is known about self-motion perception in riding simulation. The goal of this study was to examine whether or not continuous roll motion supports the sensation of leaning into bends in dynamic motorcycle simulation. To this end, riders were able to freely tune the visual scene and/or motorcycle simulator roll angle to find a pattern that matched their prior knowledge. Our results revealed idiosyncrasy in the combination of visual and proprioceptive information. Some subjects relied more on the visual dimension, but reported increased sickness symptoms with the visual roll angle. Others relied more on proprioceptive information, tuning the direction of the visual scenery to match three possible patterns. Our findings also showed that these two subgroups tuned the motorcycle simulator roll angle in a similar way. This suggests that sustained inertially specified roll motion have contributed to the sensation of leaning in spite of the occurrence of unexpected gravito-inertial stimulation during the tilt. Several hypotheses are discussed.

Practitioner Summary: Self-motion perception in motorcycle simulation is a relatively new research area. We examined how participants combined visual and proprioceptive information. Findings revealed individual differences in the visual dimension. However, participants tuned the simulator roll angle similarly, supporting the hypothesis that sustained inertially specified roll motion contributes to a leaning sensation.     

Perceived comfortable posture and optimum riding position of Indian male motorcyclists for short-duration riding of standard motorcycles

Dimensional incompatibility between rider and motorcycle is one of the most causative factors responsible for the prevalence of musculoskeletal discomfort among motorcyclists. The present study aims to identify the comfortable riding posture (CRP) and optimum riding position (ORP) for improving motorcycle design for better riding experience. The data (through image processing technique) was acquired from 120 Indian male motorcyclists (aged 19–40 years) using a static simulator test-rig. The CRP was achieved by adjusting three controls (handgrip, seat, and footrest of the test-rig), and perceived comfort and discomfort ratings. Weighed mean comfort joint angles of ten body-joints defining CRP were estimated and compared with the earlier studies. The best possible ORP among the nine test conditions (defined by the positions of the three controls) was estimated using Taguchi DOE. The study outcomes will help automobile designers to conceptualize the comfortable standard motorcycles.     

Motorcyclist's Riding Discomfort in Malaysia: Comparison of BMI,Riding Experience,Riding Duration and Riding Posture

There is very little (or no) information about the riding discomfort of motorcyclists in Malaysia. Therefore, this study was done with the intention of highlighting the relationship of the discomfort on the motorcyclist's body parts during the riding process concerning factors such as body mass index (BMI), riding experience, riding hours, and preferred riding posture. This study (questionnaire survey) was done by using 957 respondents (481 males and 476 females) with an age range from 18 years to 24 years, which was collected from a previous study. The results indicate that the majority of motorcyclists who participated in this study are in the normal BMI category. However, the majority of these motorcyclists suffer discomfort in their body parts during the riding process. It is noticeable that the majority of female motorcyclists started with higher discomfort symptoms concerning the corresponding factors (BMI, riding hours, and riding experience) compared with male motorcyclists. Most male discomfort symptoms were focused on the buttock and upper body parts, whereas the female motorcyclists experienced discomfort in all of their body parts (lower, buttocks, and upper body parts). Furthermore, the results also highlight that the motorcyclists' discomfort was correlated with riding posture. Therefore, this study clearly identified that motorcyclists experience discomfort in their body parts during the riding process. The findings also highlight that the current interaction of humans (motorcyclists) and machine (motorcycle) is not an ideal ergonomic philosophy. However, further detailed study (laboratory and field study) needs to be done to uncover fully the parameters or factors that constrain the ergonomic comfortability in the motorcycle riding process. © 2011 Wiley Periodicals, Inc.     

A study of some anthropometric characteristics of motorcycle riders

As there is little published data on motorcyclists, an anthropometric survey of 140 UK motorcyclists was undertaken, together with a brief questionnaire survey covering demographic details and motorcycling experience. Additionally an investigation of knee position on a static motorcycle test rig was undertaken. Six body dimensions relevant to the design of the riding package of a motorcycle were considered. It was found that the population of motorcyclists, both male and female, were taller than the general population with mean statures of 1774.0 and 1639.7 mm, respectively. The knee position study indicated that there was wide variation in the forward position of the knee (range 228 mm).     

交互式自行车模拟器视景仿真系统开发

视景仿真系统是交互式自行车模拟器的重要组成部分。其给骑车者提供逼真的虚拟三维漫游场景。开发的视景仿真系统硬件上采用PowerWall虚拟现实系统，软件上基于自主开发的虚拟现实通用应用开发平台VR Flier，提高了开发的效率。VR Flier采用面向对象方法设计，能够全面地支持小同领域和不同规模的VR应用开发。视景仿真系统通过优化以及动态调度三维场景模型的方法提高了大范围漫游场景的渲染帧率；并对场景路面坡度及视景转向信号进行平滑处理，获得很好的视景仿真效果。     

Sensitivity to visual speed modulation in head-mounted displays depends on fixation

A primary cause of simulator sickness in head-mounted displays (HMDs) is conflict between the visual scene displayed to the user and the visual scene expected by the brain when the user’s head is in motion. It is useful to measure perceptual sensitivity to visual speed modulation in HMDs because conditions that minimize this sensitivity may prove less likely to elicit simulator sickness. In prior research, we measured sensitivity to visual gain modulation during slow, passive, full-body yaw rotations and observed that sensitivity was reduced when subjects fixated a head-fixed target compared with when they fixated a scene-fixed target. In the current study, we investigated whether this pattern of results persists when (1) movements are faster, active head turns, and (2) visual stimuli are presented on an HMD rather than on a monitor. Subjects wore an Oculus Rift CV1 HMD and viewed a 3D scene of white points on a black background. On each trial, subjects moved their head from a central position to face a 15° eccentric target. During the head movement they fixated a point that was either head-fixed or scene-fixed, depending on condition. They then reported if the visual scene motion was too fast or too slow. Visual speed on subsequent trials was modulated according to a staircase procedure to find the speed increment that was just noticeable. Sensitivity to speed modulation during active head movement was reduced during head-fixed fixation, similar to what we observed during passive whole-body rotation. We conclude that fixation of a head-fixed target is an effective way to reduce sensitivity to visual speed modulation in HMDs, and may also be an effective strategy to reduce susceptibility to simulator sickness.     

Novel horseback riding simulator based on 6-DOF motion measurement,a motion base,and interactive control of gaits

This article describes the development process of a horseback riding simulator capable of generating a close to natural riding sensation. The development process started with 6-DOF motion measurement of the dynamics of the rider’s saddle during riding. Six-dimensional measurements during riding are required to fully understand the character of the saddle dynamics during different gaits. The measured quantities, i.e. translation accelerations and angular velocities, were transformed and filtered to form position references for a hydraulic Gough–Stewart platform. The presented novel motion measurement method is easy to use and makes it possible to measure gaits of several individual horses in a short time. It also provides a straightforward approach to produce motion data for the motion platform. In the second phase of the study, an artificial horse body made of glass fiber was mounted on the motion platform. The developed simulator realizes all three basic gaits walk, trot, and gallop. The rider is able to control the behavior of the simulator via sensors and an interactive interface. The control aids sensed by the interface are reins tension, calf pressure, and stirrup angle. A novel intelligent algorithm mimicking the real rider–horse interaction to vary the gaits and their frequencies was developed and tested.     

驾驶模拟器中车辆智能体的动力学仿真研究

在驾驶模拟器的虚拟仿真系统中,通过车辆智能体的动力学分析及运动方程计算,从而获得车辆智能体的加速度、速度、位置、发动机转速等的变化,实现车辆智能体的实时运动模拟,驱动视景系统的实时变化,并运用OpenGVS实现驾驶虚拟场景的实时生成和交互显示,由此实现驾驶仿真。     

Omnidirectional Vision and Inertial Clues for Robot Navigation

The structural features inherent in the visual motion field of a mobile robot contain useful clues about its navigation. The combination of these visual clues and additional inertial sensor information may allow reliable detection of the navigation direction for a mobile robot and also the independent motion that might be present in the 3D scene. The motion field, which is the 2D projection of the 3D scene variations induced by the camera‐robot system, is estimated through optical flow calculations. The singular points of the global optical flow field of omnidirectional image sequences indicate the translational direction of the robot as well as the deviation from its planned path. It is also possible to detect motion patterns of near obstacles or independently moving objects of the scene. In this paper, we introduce the analysis of the intrinsic features of the omnidirectional motion fields, in combination with gyroscopical information, and give some examples of this preliminary analysis. © 2004 Wiley Periodicals, Inc.     

Simulation of motorcyclist's kinematics during impact with W-Beam guardrail

W-Beam guardrail system has been in use as a standard for roadside safety barrier since 1950s. Recently, its safety performance standard has been upgraded to absorb impact from large vehicles. This performance standard requires guardrail system to be capable of capturing and redirecting a large range of vehicle types and sizes but its effects on safety of motorcyclists are not yet understood.The paper describes a three-dimensional computer simulation of the kinematics impact of motorcycle and dummy rider with W-Beam guardrail inclined at angles 45 and 90° to the initial direction of travel. The simulation is based on the test procedure recommended by ISO 13232 on the configurations for motorcycle–car impact. The focus of this study is not on the motorcycle change in velocity, but on the rider's kinematics and acceleration vs. time history.Multibody model of motorcycle and finite element model of guardrail were developed in commercially available software. The simulation results are presented in this paper in form of kinematics and acceleration vs. time history.     

Multi-view Occlusion Reasoning for Probabilistic Silhouette-Based Dynamic Scene Reconstruction

In this paper, we present an algorithm to probabilistically estimate object shapes in a 3D dynamic scene using their silhouette information derived from multiple geometrically calibrated video camcorders. The scene is represented by a 3D volume. Every object in the scene is associated with a distinctive label to represent its existence at every voxel location. The label links together automatically-learned view-specific appearance models of the respective object, so as to avoid the photometric calibration of the cameras. Generative probabilistic sensor models can be derived by analyzing the dependencies between the sensor observations and object labels. Bayesian reasoning is then applied to achieve robust reconstruction against real-world environment challenges, such as lighting variations, changing background etc. Our main contribution is to explicitly model the visual occlusion process and show: (1) static objects (such as trees or lamp posts), as parts of the pre-learned background model, can be automatically recovered as a byproduct of the inference; (2) ambiguities due to inter-occlusion between multiple dynamic objects can be alleviated, and the final reconstruction quality is drastically improved. Several indoor and outdoor real-world datasets are evaluated to verify our framework.     

Linearized motion estimation for articulated planes

In this paper, we describe the explicit application of articulation constraints for estimating the motion of a system of articulated planes. We relate articulations to the relative homography between planes and show that these articulations translate into linearized equality constraints on a linear least-squares system, which can be solved efficiently using a Karush-Kuhn-Tucker system. The articulation constraints can be applied for both gradient-based and feature-based motion estimation algorithms and to illustrate this, we describe a gradient-based motion estimation algorithm for an affine camera and a feature-based motion estimation algorithm for a projective camera that explicitly enforces articulation constraints. We show that explicit application of articulation constraints leads to numerically stable estimates of motion. The simultaneous computation of motion estimates for all of the articulated planes in a scene allows us to handle scene areas where there is limited texture information and areas that leave the field of view. Our results demonstrate the wide applicability of the algorithm in a variety of challenging real-world cases such as human body tracking, motion estimation of rigid, piecewise planar scenes, and motion estimation of triangulated meshes.     

The influence of perceptual ‘set’ on the detection of motorcyclists using daytime headlights

Abstract

Voluntary daytime headlight use by the majority of motorcyclists might endanger those not using lights: it has been suggested that drivers might scan for lights rather than for motorcyclists per se. Two experiments are described that attempted to investigate this issue in the laboratory. Subjects had to decide as rapidly as possible whether or not a motorcyclist was present in each of a series of slides depicting traffic. Experiment 1 showed that headlight-using motorcyclists were more quickly detected than unlit motorcyclists, especially when they were far away. However, repeated exposure to headlight-using motorcyclists significantly delayed detection of an unlit motorcyclist. Experiment 2 showed that this delayed-detection effect occurred when only 60% of the motorcyclists shown were using their headlight. Under laboratory conditions, at least, subjects readily appear to develop a 'set’ for responding on the basis of headlight-use, even when this is an unreliable guide to the motorcyclists’ presence.     

Using visual cues of contact to improve interactive manipulation of virtual objects in industrial assembly/maintenance simulations

This paper describes a set of visual cues of contact designed to improve the interactive manipulation of virtual objects in industrial assembly/maintenance simulations. These visual cues display information of proximity, contact and effort between virtual objects when the user manipulates a part inside a digital mock-up. The set of visual cues encloses the apparition of glyphs (arrow, disk, or sphere) when the manipulated object is close or in contact with another part of the virtual environment. Light sources can also be added at the level of contact points. A filtering technique is proposed to decrease the number of glyphs displayed at the same time. Various effects--such as change in color, change in size, and deformation of shape- can be applied to the glyphs as a function of proximity with other objects or amplitude of the contact forces. A preliminary evaluation was conducted to gather the subjective preference of a group of participants during the simulation of an automotive assembly operation. The collected questionnaires showed that participants globally appreciated our visual cues of contact. The changes in color appeared to be preferred concerning the display of distances and proximity information. Size changes and deformation effects appeared to be preferred in terms of perception of contact forces between the parts. Last, light sources were selected to focus the attention of the user on the contact areas.     

Optimal Camera Placement for Automated Surveillance Tasks

Camera placement has an enormous impact on the performance of vision systems, but the best placement to maximize performance depends on the purpose of the system. As a result, this paper focuses largely on the problem of task-specific camera placement. We propose a new camera placement method that optimizes views to provide the highest resolution images of objects and motions in the scene that are critical for the performance of some specified task (e.g. motion recognition, visual metrology, part identification, etc.). A general analytical formulation of the observation problem is developed in terms of motion statistics of a scene and resolution of observed actions resulting in an aggregate observability measure. The goal of this system is to optimize across multiple cameras the aggregate observability of the set of actions performed in a defined area. The method considers dynamic and unpredictable environments, where the subject of interest changes in time. It does not attempt to measure or reconstruct surfaces or objects, and does not use an internal model of the subjects for reference. As a result, this method differs significantly in its core formulation from camera placement solutions applied to problems such as inspection, reconstruction or the Art Gallery class of problems. We present tests of the system’s optimized camera placement solutions using real-world data in both indoor and outdoor situations and robot-based experimentation using an all terrain robot vehicle-Jr robot in an indoor setting.     

Shape sensitivity analysis and design studies for CAD flume sections

This paper presents shape design sensitivity analysis (DSA) and design studies for recreational waterslides represented in computer-aided design (CAD) environment. The mathematical representations of a number of commonly used flume sections that serve as the building blocks for waterslide configurations are created in CAD tools. Geometric dimensions of the individual sections that affect not only their geometric shape but also the overall configurations are identified as design variables. These design variables can be varied to search for better design alternatives, for example, safer waterslides. A set of coupled differential equations based on Lagrange’s equations of motion that describe the motion of the riding object are derived. The equations of motion incorporate friction forces between the riding object and the surface of the flume sections. These second-order differential equations are then solved using Mathematica. Based on the equations of motion and design variables identified, a set of differential equations are derived for calculating shape DSA coefficients. These equations are solved numerically again using Mathematica. The major contribution of the paper are (1) extending waterslide design parameterization and shape DSA computation to true CAD-based flume sections, which greatly alleviates the design for manufacturing issues previously encountered, (2) incorporating friction forces into shape DSA computation, and (3) developing a design scenario that includes sensitivity display and what-if studies for a compromised design that is safer and with a larger acceleration, therefore, higher excitement levels. Incorporating friction forces into the computation supports design for rider’s excitement levels, which are related to accelerations. Waterslide design will not be realistic without including friction forces.     

潜艇在随机海浪中摇荡运动的仿真研究

该文采用PM随机海浪频谱来实时仿真长峰波随机海浪对潜艇的随机扰动,对潜艇在海浪中的横摇和纵摇运动进行了时域仿真,潜艇在海浪中的升沉运动则采用Hirom波浪力近似计算公式进行仿真计算。所采用的仿真方法已应用于六自由度潜艇操纵训练模拟器上,结果表明该方法能比较逼真地模拟各种海情下潜艇在海浪中的运动情况,仿真实时性好,仿真精度较高。     

Detection of helmets on motorcyclists

Multimedia Tools and Applications - The use of motorcycle accidents has rapidly increased. Although the helmet is the main safety equipment of motorcyclists, many drivers do not use it. This paper...     

Probabilistic Modeling of Scene Dynamics for Applications in Visual Surveillance

We propose a novel method to model and learn the scene activity, observed by a static camera. The proposed model is very general and can be applied for solution of a variety of problems. The motion patterns of objects in the scene are modeled in the form of a multivariate nonparametric probability density function of spatiotemporal variables (object locations and transition times between them). Kernel Density Estimation is used to learn this model in a completely unsupervised fashion. Learning is accomplished by observing the trajectories of objects by a static camera over extended periods of time. It encodes the probabilistic nature of the behavior of moving objects in the scene and is useful for activity analysis applications, such as persistent tracking and anomalous motion detection. In addition, the model also captures salient scene features, such as the areas of occlusion and most likely paths. Once the model is learned, we use a unified Markov Chain Monte Carlo (MCMC)-based framework for generating the most likely paths in the scene, improving foreground detection, persistent labeling of objects during tracking, and deciding whether a given trajectory represents an anomaly to the observed motion patterns. Experiments with real-world videos are reported which validate the proposed approach.     

Imperceptible visible watermarking based on postcamera histogram operation

A real-world scene captured via digital devices, such as a digital still camera, video recorder and mobile device, is a common behavior in recent decades. With the increasing availability, reproduction and sharing of media, the intellectual property of digital media is incapable of guaranty. To claim the ownership of digital camera media, the imperceptible visible watermarking (IVW) mechanism was designed based on the observation that most camera devices contain the postcamera histogram operation. The IVW approach can achieve advantages both the content readability of invisible watermarking methodology and the visual ownership identification of visible watermarking methodology. The computational complexity of IVW is low and can be effectively applied to almost any of the digital electronic devices when capturing the real-world scene without additional instruments. The following results and analysis demonstrate the novel scheme is effective and applicable for versatile images and videos captured.