Active sensory feedback in manual machine tool operation : Effect of auditory and force sensory feedback of cutting force in fine machining

Abstract

In various manufacturing processes, manual tasks by human operators are reviewed from a new viewpoint of flexible handling ability to a wide range of object. For this ability, the information acquired through their sense organs during operation is considered to play an important role. Conversely, when the sensory information acquired is insufficient, or sensory feedback does not work well, the operators cannot fully show their ability, In this research, Tocusing on fine machining operation with a manual machine tool, a device which translates machining situation detected through industrial sensors into human sensory information has been developed and its effectiveness in improving operating efficiency, recovering fatigue and reducing tool failure has been investigated ergonomically. The authors call the sensory feedback by using this device active sensory feedback. This paper deals with active auditory feedback, active force sensory feedback and combined one. The cutting operations examined are to make a groove on a steel bar with a lathe and to make a small-diameter deep hole on an aluminum block with a milling machine. These are known as difficult and skilled machining operations, because the operators must adjust cutting force delicately so as not to break a cutting tool. So, the cutting force is adopted as the information fed back to the operator through their sensory organs. As the results, active auditory feedback was effective to improve the productivity, especially for unskilled operators. Active force sensory feedback was also effective, but not as good as active auditory one. On the contrary, any active sensory feedback was scarcely effective for very skilled operators, who could make up in the other sense what they lacked in auditory and force senses.