The effect of trial-by-trial adaptation on conflicts in haptic shared control for free-air teleoperation tasks

\u3cp\u3eHaptic shared control can improve execution of teleoperation and driving tasks. However, shared control designs may suffer from conflicts between individual human operators and constant haptic assistance when their desired trajectories differ, leading to momentarily increased forces, discomfort, or even deteriorated performance. This study investigates ways to reduce conflicts between individual human operators and a haptic shared controller by modifying supported trajectories. Subjects (n=12) performed a repetitive movement task in an abstract environment with varying spatio-temporal constraints, both during manual control and while supported by haptic shared control. Four types of haptic shared control were compared, combining two design properties: the initial supported trajectory (either the centerline of the environment or an individualized trajectory based on manual control trials), and trial-by-trial adaptation of guidance towards previously performed trajectories (either present or absent). Trial-by-trial adaptation of guidance reduced conflicts compared to non-adaptive guidance, whether the initial trajectory was individualized or not. Without trial-by-trial adaptation, individualized trajectories also reduced conflicts, but not completely: when guided, operators adapt their preferred trajectories. In conclusion, trial-by-trial adaptation is the most promising approach to mitigate conflicts during repetitive motion tasks.\u3c/p\u3

A task analysis approach to quantify bottlenecks in task completion time of telemanipulated maintenance

\u3cp\u3eTelemanipulation techniques allow for human-in-the-loop assembly and maintenance tasks in otherwise inaccessible environments. Although it comes with limitations in achieved performance - required strict operator selection and extensive training are widely encountered - there is very little quantitative insight in the exact problems operators encounter during task execution. This paper provides a novel hierarchical task analysis approach to identify the most time-consuming subtask elements and to quantify the potential room for performance improvement during telemanipulated maintenance tasks. The approach is illustrated with a human factors case study in which 5 subjects performed six generic maintenance tasks, using a six degree of freedom master device connected to a simulated task environment. Overall it can be concluded that the proposed three phased task analysis is a useful tool to guide improvements since it is able to relate high-level problems (e.g. large variability) to behaviour on lower task-levels. For the case study, the largest potential for improvement was found for specific subtasks characterized by complex contact transitions and precise control of tool orientation, and in the reduction of variation of the task execution.\u3c/p\u3

Where to improve in human-in-the-loop tele-operated maintenance? a phased task analysis based on video data of maintenance at JET

\u3cp\u3eFor the planned teleoperated maintenance of the experimental fusion plant ITER the time performance will be critical. Telemanipulated task execution is however characterised by long execution times compared to similar tasks performed hands-on. There is little quantitative research on task performance of telemanipulated maintenance available to give insight into most effective areas for improvement.In this paper a detailed analysis of real world remote maintenance at fusion plant JET is performed with the aim to: i) identify bottlenecks in task completion time and ii) quantify the room for potential improvement.Video recordings of the installation of 50 tiles executed by the three official master-slave operators were analysed. The task execution was characterised by a large variation in time performance, between but also within operators. Reduction of this variation could theoretically result in time reduction up to 41%. Recurring tasks like 'rough/fine approach' and 'retreat' covered more than 50% of the total task completion time and were identified as most promising for further improvement.The results will be the base for further research on operator assistance with augmented visual or haptic guidance.\u3c/p\u3

Haptic assistance improves tele-manipulation with two asymmetric slaves

\u3cp\u3eTele-manipulation of heavy loads typically requires the simultaneous use of two asymmetric slaves: a crane for vertical weight support and a robot for accurate lateral positioning. The industrial standard prescribes a pair of operators for such tasks (one operator to control each slave), although in principle one operator might control both slaves with a single, hybrid interface. Accurate and safe co-operative handling of the expensive and fragile heavy components is difficult, presumably due to problems in the coordination of the subtasks and the lack of mutual awareness between the two operators. This study proposes a novel haptic assistance system to improve subtask coordination and task performance. Its novelty consists of haptically linking operators/interfaces through the joint task environment. The system's efficacy is evaluated with 15 pairs of co-operators and 15 individual uni-manual operators who maneuvered a heavy load through a bounded path in Virtual Reality. Haptic assistance improves task completion time for both groups. It also reduces control activity and self-reported workload without affecting a number of critical errors made by the operators. Moreover, without haptic assistance, uni-manual operators perform worse than co-operators, but this difference between the interfaces was not found with haptic assistance.\u3c/p\u3

Analysis of human-in-the-loop tele-operated maintenance inspection tasks using VR

One of the challenges in future fusion plants such as ITER is the remote maintenance of the plant. Foreseen human-in-the-loop tele-operation is characterized by limited visual and haptic feedback from the environment, which results in degraded task performance and increased operator workload. For improved tele-operated task performance it is required to get insight in the expected tasks and problems during maintenance at ITER. By means of an exploratory human factor experiment, this paper analyses problems and bottlenecks during the execution of foreseen tele-operated maintenance at ITER, identifying most promising areas of improvement. The focus of this paper is on free space (sub)tasks where contact with the environment needs to be avoided. A group of 5 subjects was asked to carry-out an ITER related free space task (visual inspection), using a six degree of freedom master device connected to a simulated hot cell environment. The results show large variation in time performance between subjects and an increasing number of collisions for more difficult tasks, indicating room for improvement for free space (sub)tasks. The results will be used in future research on the haptic guidance strategies in the ITER Remote Handling framework. (C) 2013 FOM institute DIFFER (Dutch Institute for Fundamental Energy Research). Published by Elsevier B.V. All rights reserved