The visual control of bicycle steering: The effects of speed and path width

Although cycling is a widespread form of transportation, little is known about the visual behaviour of bicycle users. This study examined whether the visual behaviour of cyclists can be explained by the two-level model of steering described for car driving, and how it is influenced by cycling speed and lane width. In addition, this study investigated whether travel fixations, described during walking, can also be found during a cycling task. Twelve adult participants were asked to cycle three 15 m long cycling lanes of 10, 25 and 40 cm wide at three different self-selected speeds (i.e., slow, preferred and fast). Participants’ gaze behaviour was recorded at 50 Hz using a head mounted eye tracker and the resulting scene video with overlay gaze cursor was analysed frame by frame. Four types of fixations were distinguished: (1) travel fixations, (2) fixations inside the cycling lane (path), (3) fixations to the final metre of the lane (goal), and (4) fixations outside of the cycling lane (external). Participants were found to mainly watch the path (41%) and goal (40%) region while very few travel fixations were made (<5%). Instead of travel fixations, an OptoKinetic Nystagmus was revealed when looking at the near path. Large variability between subjects in fixation location suggests that different strategies were used. Wider lanes resulted in a shift of gaze towards the end of the lane and to external regions, whereas higher cycling speeds resulted in a more distant gaze behaviour and more travel fixations. To conclude, the two-level model of steering as described for car driving is not fully in line with our findings during cycling, but the assumption that both the near and the far region is necessary for efficient steering seems valid. A new model for visual behaviour during goal directed locomotion is presented.     

Identifying cognitive distraction using steering wheel reversal rates

The influence of driver distraction on driving performance is not yet well understood, but it can have detrimental effects on road safety. In this study, we examined the effects of visual and non-visual distractions during driving, using a high-fidelity driving simulator. The visual task was presented either at an offset angle on an in-vehicle screen, or on the back of a moving lead vehicle. Similar to results from previous studies in this area, non-visual (cognitive) distraction resulted in improved lane keeping performance and increased gaze concentration towards the centre of the road, compared to baseline driving, and further examination of the steering control metrics indicated an increase in steering wheel reversal rates, steering wheel acceleration, and steering entropy. We show, for the first time, that when the visual task is presented centrally, drivers’ lane deviation reduces (similar to non-visual distraction), whilst measures of steering control, overall, indicated more steering activity, compared to baseline. When using a visual task that required the diversion of gaze to an in-vehicle display, but without a manual element, lane keeping performance was similar to baseline driving. Steering wheel reversal rates were found to adequately tease apart the effects of non-visual distraction (increase of 0.5° reversals) and visual distraction with offset gaze direction (increase of 2.5° reversals). These findings are discussed in terms of steering control during different types of in-vehicle distraction, and the possible role of manual interference by distracting secondary tasks.     

4WID-4WIS智能车阿克曼转向轨迹规划及位置估算

针对四轮独立驱动与四轮独立转向(four-wheel independent drive and four-wheel independent steering,4WID-4WIS)智能车的转向行驶工况,基于阿克曼转向原理,提出一种利用三阶贝塞尔曲线进行轨迹规划的新方法.首先,采用最优函数获取一条满足智能车初始状态约束...     

Leading to distraction: Driver distraction,lead car,and road environment

Driver distraction is strongly associated with crashes and near-misses, and despite the attention this topic has received in recent years, the effect of different types of distracting task on driving performance remains unclear. In the case of non-visual distractions, such as talking on the phone or other engaging verbal tasks that do not require a visual input, a common finding is reduced lateral variability in steering and gaze patterns where participants concentrate their gaze towards the centre of the road and their steering control is less variable. In the experiments presented here, we examined whether this finding is more pronounced in the presence of a lead car (which may provide a focus point for gaze) and whether the behaviour of the lead car has any influence on the driver's steering control. In addition, both visual and non-visual distraction tasks were used, and their effect on different road environments (straight and curved roadways) was assessed. Visual distraction was found to increase variability in both gaze patterns and steering control, non-visual distraction reduced gaze and steering variability in conditions without a lead car; in the conditions where a lead car was present there was no significant difference from baseline. The lateral behaviour of the lead car did not have an effect on steering performance, a finding which indicates that a lead car may not necessarily be used as an information point. Finally, the effects of driver distraction were different for straight and curved roadways, indicating a stronger influence of the road environment in steering than previously thought.     

机器人纸箱套装系统的轨迹规划与分析验证

目的保证机器人纸箱套装系统稳定工作,提高包装质量与效率。方法对系统进行整体规划后,确定纸箱套装系统的轨迹点,对不同的运动过程分别在关节空间中和笛卡尔空间中进行轨迹规划,并生成各关节插值曲线。借助Matlab对机器人进行仿真实验,得出各关节角度规划曲线,并将之与轨迹规划所得结果进行比较。利用机器人实物对轨迹规划进行验证。结果各关节插值曲线与角度规划曲线吻合,角度规划曲线平滑。结论选用的套箱机器人轨迹规划方法可行,结果正确。     

Visual guidance during bicycle steering through narrow lanes: A study in children

Recently, Vansteenkiste et al. (2013) explored how visual behaviour guides bicycle steering when cycling at different speeds through 15 m long lanes of 10, 25 and 40 cm wide. Participants were found to shift their gaze direction towards the end of the lanes at higher speeds, towards the near pathway on narrow lanes and more towards irrelevant areas on wider lanes. To investigate to what extent young learner bicyclists adapt their visual behaviour in a similar way as adults, the experiment was repeated with seven eight-year-old children, and results were compared to the adult data. Children were found to cycle slower through narrow lanes than adults. However, with increasing lane width and cycling speed, children made the same shifts of visual gaze direction as the adults. These results suggest that for a simple precision steering task, children are able to adopt a similar visual-motor strategy as adults, provided that they cycle at their own pace.     

Through the eyes of a bird: modelling visually guided obstacle flight

Various flight navigation strategies for birds have been identified at the large spatial scales of migratory and homing behaviours. However, relatively little is known about close-range obstacle negotiation through cluttered environments. To examine obstacle flight guidance, we tracked pigeons (Columba livia) flying through an artificial forest of vertical poles. Interestingly, pigeons adjusted their flight path only approximately 1.5 m from the forest entry, suggesting a reactive mode of path planning. Combining flight trajectories with obstacle pole positions, we reconstructed the visual experience of the pigeons throughout obstacle flights. Assuming proportional–derivative control with a constant delay, we searched the relevant parameter space of steering gains and visuomotor delays that best explained the observed steering. We found that a pigeon''s steering resembles proportional control driven by the error angle between the flight direction and the desired opening, or gap, between obstacles. Using this pigeon steering controller, we simulated obstacle flights and showed that pigeons do not simply steer to the nearest opening in the direction of flight or destination. Pigeons bias their flight direction towards larger visual gaps when making fast steering decisions. The proposed behavioural modelling method converts the obstacle avoidance behaviour into a (piecewise) target-aiming behaviour, which is better defined and understood. This study demonstrates how such an approach decomposes open-loop free-flight behaviours into components that can be independently evaluated.     

基于五次多项式的码垛机器人轨迹规划

目的为了实现多轴码垛机器人速度和加速度变化曲线光滑、稳定,简化轨迹规划算法。方法介绍码垛机器人结构,并在码垛机器人结构基础上对码垛机器人运动进行分析,在关节空间下提出一种五次多项式插值的码垛机器人轨迹规划方法,利用五次函数对码垛机器人各个关节速度和加速度进行拟合插值。结果仿真结果表明,五次多项式轨迹规划方法拟合曲线更加光滑,同时保证速度和加速度无突变,保证了码垛机器人运动过程更加平稳。结论该轨迹规划方法能够保证码垛机器人按照预定的轨迹实现速度和加速度的平滑过渡,提升了码垛机器人运动精度。     

Modeling extreme loads acting on steering components using driving events

Forces during steering events, such as curves and maneuvers, cause large stresses on steering components. In this paper, we formulate a model for the lateral loads causing fatigue damage of the steering components. Steering events are identified using a Hidden Markov model on the CAN (Controller Area Network) bus data. The CAN data is available on all vehicles, thus the model is applicable across many types of vehicles. To identify the events, the observation from CAN data is modeled by a multivariate generalized Laplace (GAL) distribution. An explicit formula for the expected fatigue damage is given. Results are validated using measured lateral acceleration.     

基于遗传算法的电容装盘机器人轨迹规划

目的为了改变电容人工装盘方式,提高电容装盘自动化程度及效率,选用SCARA型机器人代替人工方式,并对其进行轨迹规划,避免运动冲击影响电容装盘稳定性以及精确性。方法首先介绍SCARA机器人的结构和电容装盘过程,然后利用五次非均匀B样条曲线完成轨迹曲线的构造,最后提出带罚函数的遗传算法,以实现时间最优的机器人轨迹规划过程。结果仿真结果表明,机器人装盘时间用时更短,且运动平稳无冲击,验证了算法的有效性。结论该轨迹规划方法能够满足实际生产要求,提高了电容搬运装盘质量及效率。     

Consistency and sensitivity of lane change test according to driving simulator characteristics

The aim, here, is to evaluate consistency and sensitivity of the lane change test (LCT), which is the subject of a proposed ISO standard. The method is intended to estimate driver distraction while a secondary task is being performed, by measuring performance degradation on a primary driving-like task. An experiment was conducted in two experimental contexts: a fixed-base driving simulator and a personal computer (PC) (including pedals and steering wheel), and with two auditory and two visual?manual secondary tasks. Three performance measures were calculated: adapted mean deviation, correct lane change (LC) ratio and mean delay in LC initiation. The effect of experimental context was significant. The trajectory, measured by the adapted mean deviation, was significantly better on the simulator and the percentage of correct LC higher. This difference might be explained by the greater immersion of the driver in the driving scene, which led to easier control of the trajectory in the simulator. Conversely, participants initiated quicker responses to signs when using the PC, to the detriment of trajectory control. The LCT was also proved to be sensitive enough to evaluate driving performance impairment because of the simultaneous performance of secondary tasks, even if it failed to differentiate all of them.     

Combining cognitive and visual distraction: Less than the sum of its parts

Driver distraction has become a leading cause of motor-vehicle crashes. Although visual and cognitive distraction has been studied extensively, relatively little research has addressed their combined effects on drivers’ behavior. To fill this gap, a medium-fidelity simulator study examined the driver behavior before, during and after three types of distraction. Driving without distraction was compared to visual distraction, cognitive distraction, and combined visual and cognitive distraction. The results show that the visual and combined distraction both impaired vehicle control and hazard detection and resulted in frequent, long off-road glances. The combined distraction was less detrimental than visual distraction alone. Cognitive distraction made steering less smooth, but improved lane maintenance. All distractions caused gaze concentration and slow saccades when drivers looked at the roadway, and cognitive and combined distraction increased blink frequency. Steering neglect, under-compensation, and over-compensation were three typical steering failures that were differentially associated with the different distractions: steering neglect and over-compensation with visual distraction and under-compensation with cognitive distraction. Overall, visual distraction interferes with driving performance more than cognitive distraction, and visual distraction dominates the performance decrements during combined distraction. These results suggest that minimizing visual demand is particularly important in the design of in-vehicle systems and in the development of distraction countermeasures.     

基于混沌粒子群优化算法的AGV路径规划研究

目的 优化物流AGV路径最优问题。方法 提出一种改进的混沌粒子群优化算法,采用基于Bézier曲线的路径规划模型,通过调整Bézier曲线的控制点数量,显著改善AGV轨迹路线的长度和平滑度。结果 采用混沌粒子群滤波算法（CPSO）最优化处理Bézier曲线的控制点数,引入适应度函数,评估是否满足终止标准,如果达到最大迭代次数或者在给定迭代次数时未修改最优解则终止CPSO算法,最后利用选取的控制点计算出更短、更平滑的轨迹路线,提高了算法的寻优能力。结论 采用CPSO算法初始化Bézier曲线可以获得更加平滑的最短路径。     

A Hybrid Path Planning Method Based on Articulated Vehicle Model

Due to the unique steering mechanism and driving characteristics of the articulated vehicle, a hybrid path planning method based on the articulated vehicle model is proposed to meet the demand of obstacle avoidance and searching the path back and forth of the articulated vehicle. First, Support Vector Machine (SVM) theory is used to obtain the two-dimensional optimal zero potential curve and the maximum margin, and then, several key points are selected from the optimal zero potential curves by using Longest Accessible Path (LAP) method. Next, the Cubic Bezier (CB) curve is adopted to connect the curve that satisfies the curvature constraint of the articulated vehicle between every two key points. Finally, Back and Forth Rapidly-exploring Random Tree with Course Correction (BFRRT-CC) is designed to connect paths that do not meet articulated vehicle curvature requirements. Simulation results show that the proposed hybrid path planning method can search a feasible path with a 90-degree turn, which meets the demand for obstacle avoidance and articulated vehicle back-and-forth movement.     

Scheduling vehicles in automated transportation systems Algorithms and case study

One of the major planning issues in large scale automated transportation systems is so-called empty vehicle management, the timely supply of vehicles to terminals in order to reduce cargo waiting times. Motivated by a Dutch pilot project on an underground cargo transportation system using Automated Guided Vehicles (AGVs), we developed several rules and algorithms for empty vehicle management, varying from trivial First-Come, First-Served (FCFS) via look-ahead rules to integral planning. For our application, we focus on attaining customer service levels in the presence of varying order priorities, taking into account resource capacities and the relation to other planning decisions, such as terminal management. We show how the various rules are embedded in a framework for logistics control of automated transportation networks. Using simulation, the planning options are evaluated on their performance in terms of customer service levels, AGV requirements and empty travel distances. Based on our experiments, we conclude that look-ahead rules have significant advantages above FCFS. A more advanced so-called serial scheduling method outperforms the look-ahead rules if the peak demand quickly moves amongst routes in the system. Received: June 21, 2000 / Accepted: January 22, 2001     

Recognisability of different configurations of front lights on motorcycles

One often discussed reason for motorcyclists' high risk of accidents is that they are less conspicuous to other road users than are other motorised vehicles. The present paper aims to identify a front signal pattern created by additional light sources that would make motorcycles clearly and quickly distinguishable from other vehicles, and that would therefore facilitate localisation and identification of motorcycles. Results of a laboratory experiment have shown that motorcycles with a T-shaped light configuration are more quickly identified, particularly when the motorcycles are in visual competition with other motorised road users. Furthermore, analysis of gaze behavior showed that they were faster fixated by the subjects in the experiment, and the mean duration of fixations was shorter. The practical implications of this experiment and the need for further research are discussed.     

基于圆柱螺线法的偏置机构控制算法仿真及实验研究

偏置机构芯轴偏心位移的精确控制是实现导向钻进的核心问题.针对一种新型静态指向式偏置机构,首先介绍了其结构组成以及轨迹控制原理;其次,建立基于圆柱螺线法的井眼轨迹控制算法数学模型,并以三维多目标井眼轨迹为例,讨论了如何通过该机构实现井眼轨迹的控制,并基于SolidWorks和ADAMS进行机构虚拟模型的建立和运动仿真,得到偏置机构运动情况曲线;最后,建立基于LabVIEW的实验平台对偏置机构样机的导向性能进行验证.通过仿真结果、实验值和理论值的比较,确定该算法产生较好的控制效果,证明了实现机构导向控制的可行性,从而为旋转导向钻井工具实际轨迹控制算法设计与优化奠定理论基础.     

基于Dobot机械臂的包装自动线运动规划与仿真

目的 针对手工包装作业劳动强度大、生产速率低、一致性差等问题,基于Dobot轻型机械臂设计一种针对校园纪念品包装的自动化线.方法 首先对自动包装线各工序进行分析,确定各工步关键路径点,对各工序内的工步机械臂运动进行轨迹规划.其次利用Robotics Toolbox工具箱建立机械臂仿真模型,进行运动仿真分析.最后联合Matlab和Inventor进行可视化运动虚拟仿真.结果 运动仿真结果显示,在机械臂执行轨迹规划任务过程中各关节角位移无突变,且角速度和角加速度曲线平滑,能保证机械臂运行平稳,可视化虚拟仿真显示机械臂运行平顺.结论 证明各工序机械臂运动规划可行,符合各工步任务要求,可以满足包装自动化任务要求.     

基于MATLAB的机械臂运动学分析和轨迹规划

目的 研究包装机械臂运动学和轨迹规划,以实现机器臂的平稳运行和精确控制。方法 以六自由度包装机械臂模型为研究对象,采用改进的D–H参数法建立坐标系,推导运动学方程,运用MATLAB搭建机械臂模型并进行正逆运动学仿真,以验证模型的正确性。其次,采用五次多项式插值算法对机械臂关节空间进行轨迹规划。最后,针对包装作业中待包装产品的定点抓取搬运任务进行轨迹规划和仿真。结果 搭建的机械臂模型正确,五次多项式插值法轨迹优化效果好,可保证各关节角度、速度和加速度曲线光滑连续;计算出抓取搬运任务中各关节的关节量,并得到了末端执行器运动轨迹曲线。结论 机械臂能以预期的运动精度完成抓取搬运的动作,为进一步探究机械臂的运动控制和实际应用奠定了基础。     

Study on the parameters relationship of PM2 planning model

ABSTRACT

Planning is important in the process of engineering reliability and growth. Planning models and the related curves are always influenced by their intrinsic parameters. However, there is little research on the relationship between planning models and their inherent parameters. This study examines the relationships between the planning model based on projection methodology (PM2 model) and its four inherent parameters. The results have shown that all four parameters have a significant influence on the reliability growth-planning curve. Moreover, they reveal that some parameters have minimum limits. By prejudging the parameters of the model, the risk of not achieving the test target can be reduced. This study will provide guidance for future engineering planning and management.