Evaluation

Motion Canceling Test

Preliminary testing of Micron 1 tremor canceling has been conducted using a motorized testbed, shown in Fig. 1, to generate oscillatory motion, simulating the hand tremor of the surgeon.  The oscillating plate on which Micron was mounted rested on a linear slide. A spring-loaded driving shaft, attached to the back end of the plate, was driven at roughly 9 Hz by a cam rotated using a DC servomotor. 

.  Two types of tests were conducted:

·        1-D, involving motion only along the long axis (Z) of the instrument, at 50 mm p-p.

·        3-D, using a 90 mm p-p oscillation.  Table II shows the uncompensated magnitude of input oscillation in each of the three body coordinates of the instrument.

In each case 12 trials were conducted.  A small marker ball was mounted at the instrument tip, and ASAP was used to track tip position.  The instrument sampled data at 1000 Hz.

Rather than report rms values, we have multiplied rms results by 2√2 to obtain the equivalent peak-to-peak amplitude that would result if the signal were a perfect sinusoid.  This is proposed as a more clinically meaningful metric, as the surgeon is interested in the overall excursion of undesired motion, not in its rms amplitude.

Fig. 1.

In the tests involving only axial motion, the average erroneous motion amplitude was reduced from 51 mm p-p to 25 mm p-p, a reduction of 51%.  Sample results from the 1-D tests are shown in Fig. 2.

 

Fig. 2.

In 3-D canceling tests the average vector amplitude of erroneous motion was reduced from 91 mm p-p to 60 mm p-p, representing a 34% reduction over 12 trials.   Fig. 3 shows typical results for the 3-D tests.  The spectral content of a typical 3-D test can be seen in Fig. 4.

Fig. 3(a).

Fig. 3(b).

Fig. 3(c).

Fig. 4.

 

Surgeons’ acceptance evaluation

 Video

 

 

Return to Research Activity

Return to Micron 1