Italian Institute of Technology, RBCS Department, Genoa, Italy.
PLoS One. 2010 Jun 17;5(6):e11189. doi: 10.1371/journal.pone.0011189.
This study addresses force/movement control in a dynamic "hybrid" task: the master sub-task is continuous manual tracking of a target moving along an eight-shaped Lissajous figure, with the tracking error as the primary performance index; the slave sub-task is compensation of a disturbing curl viscous field, compatibly with the primary performance index. The two sub-tasks are correlated because the lateral force the subject must exert on the eight-shape must be proportional to the longitudinal movement speed in order to perform a good tracking. The results confirm that visuo-manual tracking is characterized by an intermittent control mechanism, in agreement with previous work; the novel finding is that the overall control patterns are not altered by the presence of a large deviating force field, if compared with the undisturbed condition. It is also found that the control of interaction-forces is achieved by a combination of arm stiffness properties and direct force control, as suggested by the systematic lateral deviation of the trajectories from the nominal path and the comparison between perturbed trials and catch trials. The coordination of the two sub-tasks is quickly learnt after the activation of the deviating force field and is achieved by a combination of force and the stiffness components (about 80% vs. 20%), which is a function of the implicit accuracy of the tracking task.
本研究针对动态“混合”任务中的力/运动控制进行了研究：主任务是连续手动跟踪沿着八字形李萨如图形移动的目标，以跟踪误差作为主要性能指标；从任务是补偿具有卷曲粘性的干扰场，与主要性能指标兼容。这两个子任务是相关的，因为主体必须施加在八字形上的横向力必须与纵向运动速度成正比，以便进行良好的跟踪。结果证实，视动跟踪的特点是间歇性控制机制，与以前的工作一致；新的发现是，如果与未受干扰的情况相比，存在较大的偏离力场并不会改变整体控制模式。还发现，交互力的控制是通过臂刚度特性和直接力控制的组合来实现的，这正如轨迹从标称路径的系统侧向偏差以及受扰试验和捕获试验之间的比较所表明的那样。在偏离力场激活后，两个子任务的协调可以快速学习，并通过力和刚度分量（约 80%对 20%）的组合来实现，这是跟踪任务隐含精度的函数。
