Certain tele-manipulation tasks require manipulation by two asymmetric slaves, for example a crane for hoisting and a dexterous robotic arm for fine manipulation. It is unclear how to best design human-in-the-loop control over two asymmetric slaves. The goal of this paper is to quantitatively compare the standard approach of two co-operating operators that each control a single subtask, to a single operator performing bimanual control over the two subtasks, and a uni-manual control approach.@en

Tele-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 fifteen pairs of co-operators and fifteen individual uni-manual operators who manoeuvred 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 disappears with haptic assistance.@en

For 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.@en

Telemanipulation 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.@en