Designer and ideas guy Steve Hoefer calls his invention “Tacit” because it seems appropriate, but also because “Hand-Mounted Haptic Feedback Sonar Obstacle Avoidance Assistance Device” sounds a little unwieldy. In essence, it’s a wrist-mounted device that helps a vision-impaired person to navigate complex environments by measuring the distance to things and translating that information into pressure on the wrist.

It senses objects from about 2 cm to 3,5 m distant, reacting within fractions of a second to alert the wearer. Says Hofer: “The learning curve is measured in seconds… everyone who has worn it has figured it out immediately.” He makes the point that image-simulating sensors need not be located on the head, citing an earlier “haptic headband” prototype equipped with little motors that vibrated faster as the wearer approached an obstacle.

Although the basic idea was sound, he says, it became apparent that the most dangerous obstacles were not at head level. “Also, vibrating motors stuck on your skull would drive you insane quickly.” Quite.

Watch a short video on www.popularmechanics.co.za that shows Tacit in action.