PANTOGRAPH MECHANISM FOR INCREASING THE WORKING AREA IN A HAPTIC GUIDANCE DEVICE FOR SKETCHING, HATCHING AND CUTTING TASKS

摘要

The paper presents the design, construction, validation and testing of a Haptic Guidance Device whose aim is to provide dynamic assistance while performing manual activities such as drawing, hatching and cutting. A commercial phantom haptic device was modified by adding a pantograph mechanism in order to increase the haptic working area. The force feedback workspace provided by the phantom device is quite limited, 160 W x 120 H mm. This workspace sometimes is not enough to reproduce manual tasks in a large-scale area as is often required in several educational activities (e.g. sketching, hatching and cutting tasks). In this paper is evaluated a low cost solution for increasing the haptic working area provided by the phantom device. The pantograph mechanism has been linked with the haptic device in order to increase the working area in a 2:1 scale. The users hand moves a pen linked to the device through 2D predefined shapes in which the pens position have been tracked in 2D coordinates at 25 kHz in order to record all the data for the posterior analysis. The haptic guidance device is also equipped with a cutting system using hot wire for physically producing the drawn shape as a piece of polystyrene foam. The haptic guidance device has been tested by people with specific disorders affecting coordination such as Down syndrome and mental retardation under the supervision of their teachers and care assistants. The results of the study prove that higher performance levels can be achieved while performing manual tasks as sketching, hatching and cutting operation using the haptic guidance device.