Haptic assistance to mitigate damaging vertical accelerations of small ships in head waves

Crew of small fast ships often experiences excessive vertical accelerations when sailing in waves, leading to discomfort and injuries. In an attempt to avoid this, experienced operators reduce speed voluntarily when they anticipate that the next vertical peak acceleration will be unacceptably large. However, at night and during excessive spray, the operator can hardly see the environment which makes it almost impossible to anticipate wave driven events. On top of that, this approach carries the risk of operator misjudgement due to loss of concentration or fatigue.
The objective of this paper is to investigate the potential of using haptic assistance to support operators in preventing excessive vertical accelerations, by using haptic speed advice on the throttle based on experienced wave statistics.
A stochastic based approach was used to construct a haptic algorithm, which gives a maximum advisable propeller speed setting based on an estimate of the current sea state. To test the effectiveness of this approach, a human-in-the-loop experiment was conducted. The effect of haptic assistance was compared to manual control under both good and reduced visibility conditions.
No significant decrease in the number of excessive accelerations was achieved when comparing equal conditions in the current experiment, although subjects controlled the ship with reduced workload.
The lack of significance indicates a difference in control strategy between the participants, for 16 out of 22 participants experienced less excessive accelerations when sailing shared control.