An Optical 6-Axis Force Sensor for Brain Function Analysis using fMRI

MRI Compatible Robot Systems for Medical Intervention

“…Optical signals do not interfere with magnetic field. Optical sensors have been developed and used for sensing position (Fischer et al, 2008b, Hempel et al, 2003, Hata et al, 2008 and force (Harja et al, 2007, Takahashi et al, 2003 in an MRI environment. A commercially available optical encoder from US digital (Vancouver, Washington, USA) uses transmissive strips for positioning the motion.…”

Torque Sensors for Robot Joint Control

“…Compared to conventional straingauge-based transducers, they are more compact, lightweight, and cheap, but they have complicated calibration due to nonlinear output, require application of DSP for real-time computation of measured force, and have an average accuracy of 5% FS. At Nara Institute of Science and Technology, a 6-axis optical force/torque sensor was developed for fMRI application (Takahashi et al, 2003). The sensor was made from acrylic resin to eliminate any metal sensor components that generate fMRI signal noise.…”

“…3. Layout of the 6-axis optical force/torque sensor (Takahashi et al, 2003) The 6-axis force/torque converter using LEDs and photodiodes is described in (Hilton, 1989). The list of desirable properties of torque sensor aimed at integration into anthropomorphic robot arm is given below.…”

An MR-Compatible Optical Force Sensor for Human Function Modeling

“…This configuration has distinct advantages over the conventional design [7,8] in which the light source and the sensing device are placed on separate bases and their relative displacement is measured. Firstly, displacement is magnified by a factor of two (higher precision).…”

“…We have recently proposed an MR-compatible force sensor [7,8] based on an optical micrometry [9] using an LED and a quadrant photo diode. It achieves MR compatibility by placing both optical elements outside the MRI and extending a light path between them by using fiber optics.…”