Design and Calibration of an Optical Micro Motion Sensing System for Micromanipulation Tasks

Abstract

An optical sensing system has been developed using a pair of orthogonally placed position sensitive detectors (PSD) to track 3D displacement of a microsurgical instrument tip in real-time. An infrared (IR) diode is used to illuminate the workspace. A ball is attached to the tip of an intraocular shaft to reflect IR rays onto the PSDs. Instrument tip position is then calculated from the centroid positions of reflected IR light on the respective PSDs. The system can be used to assess the accuracy of hand-held microsurgical instruments and operator performance in micromanipulation tasks, such as microsurgeries. In order to eliminate inherent nonlinearity of the PSDs and lenses, calibration is performed using a feedforward neural network. After calibration, percentage RMS error is reduced from about 5.46 % to about 0.16%. The system RMS noise is about 0.7 µm. The sampling rate of the system is 250 Hz.

Design and implementation of a two degree-of-freedom micromanipulation assessment system

“…The calculation of the laser spot in the system (SAAM) in [12] requires ball position information provided by (M 2 S 2 ) system [13] and the knowledge of orientation of the instrument. The accelerometers are employed in the system [12] to detect tilt angle of the instrument and assuming that subjects who perform the manipulation tests would maintain the pan angle of the instrument constant.…”

“…In response to the need for investigation, the authors developed a system to asses accuracy of micromanipulation (SAAM) [12] using an optical micro motion sensing system (M 2 S 2 ) [13] and studied manipulation accuracy and physiological tremor of subjects performing both static and dynamic micromanipulation tasks without having occlusion problem.…”

System to Assess Accuracy of Micromanipulation

“…In order to perform static as well as dynamic tests, a target platform which is cylindrical in shape is placed at the center of the workspace of M 2 S 2 [12] in x and y direction and just below the workspace in z direction as shown in A stepper motor is used to rotate the target platform in the dynamic tests. The cylindrical target platform is painted with non-reflective black color to prevent the IR light from reflecting from the platform to the PSDs in order not to reduce the signal-to-noise ratio.…”

“…optical Micro Motion Sensing System[12] which the authors have developed. M 2 S 2 system consists of a pair of orthogonally placed position sensitive detectors (PSD), a lens in front of each PSD, an IR diode together with a lens in front, a white reflective ball and a data acquisition (DAQ) system.…”

A micro motion sensing system for micromanipulation tasks

“…To address the above issues, motion sensing systems which can sense microsurgical instrument motion in micro scale are developed based on a passive tracking method [20][21][22], or an active tracking method [23][24][25]. Although systems based on active tracking method (active tracking systems) can provide high resolution due to high intensity light reception at the sensors, the light sources have to be fixed on the instrument to be tracked, requiring electronics and wires on the instrument.…”