Development of a biomimetic position sensor for robotic kinaesthesia

Drawing from the rich source of proven and often novel mechanisms in the biological realm, biomimetic sensors are being successfully developed for many different transduction tasks. This paper presents such a sensor for transducing displacements. Our sensor is a robotic analog of the biological muscle spindle, an actuated position sensor which transduces muscle displacement for kinesthetic awareness. The mechanical filter exhibits the desired step response with Tr=26 msec, Ts=54 msec, P.O. = 3.7%, Ess=6.8x10mm. The transducer possesses the desired linear response with a sensitivity of 34nm/Hz. Finally, the encoder circuitry successfully maps the millivolt output to a pulse frequency range of 1150Hz to 12.5kHz. Results from an integrated system test show that the sensor can successfully detect errors in trajectory tracking introduced by both phase lag and perturbations. By physically realizing the hypothesized core features of a biological muscle spindle in engineering hardware, we evoked the type of actuated sensor output seen in the biological muscle spindle, a widely utilized tool of biological motor control.