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A new type of cable-driven continuum manipulator (CM) is presented, in which the stiffness of the device along its body length can be controlled using the thermomechanical properties of a phase changing alloy. The liquid phase of the alloy is used for achieving high dexterity and the solid phase for high stiffness. Joule heating and water cooling is used(More)
Magnetic Resonance Imaging (MRI) combined with robotic assistance has the potential to improve on clinical outcomes of biopsy and local treatment of prostate cancer. We report the workspace optimization and phantom evaluation of a five Degree of Freedom (DOF) parallel pneumatically actuated modular robot for MRI-guided prostate biopsy. To shorten procedure(More)
During prostate needle insertion, the gland rotates and displaces resulting in needle placement inaccuracy. To compensate for this error, we proposed master-slave needle steering under real-time MRI in a previous study. For MRI-compatibility and accurate motion control, the master (and the slave) robot uses piezo actuators. These actuators however, are(More)
Accurate needle placement plays a key role in success of prostate biopsy and brachytherapy. During percutaneous interventions, the prostate gland rotates and deforms which may cause significant target displacement. In these cases straight needle trajectory is not sufficient for precise targeting. Although needle spinning and fast insertion may be helpful,(More)
To evaluate the targeting accuracy of a small profile MRI-compatible pneumatic robot for needle placement that can angulate a needle insertion path into a large accessible target volume. We extended our MRI-compatible pneumatic robot for needle placement to utilize its four degrees-of-freedom (4-DOF) mechanism with two parallel triangular structures and(More)
The piezoelectric actuator (PEA) accuracy is limited due to hysteresis nonlinearity as well as mechanical loading effect. Investigation of the fundamental properties of the piezoceramics depicts that the external mechanical loads cause inclination in hysteresis loop can deteriorate tracking performance furthermore. Other limiting problem is the rate(More)
The slave robot in this research is a 1-DOF piezo actuator which includes hysteresis nonlinearity. Nonlinear hysteresis behavior makes robot control a complex task. In this research, the nonlinear and uncertain dynamics of the slave robot has been considered through the teleoperation control loop. LuGre friction model is used as the estimator of the(More)
BACKGROUND Accurate needle placement is the first concern in percutaneous MRI-guided prostate interventions. In this phantom study, different sources contributing to the overall needle placement error of a MRI-guided robot for prostate biopsy have been identified, quantified and minimized to the possible extent. METHODS The overall needle placement error(More)
This study presents one of the enabling technologies for teleoperated bevel-tip needle steering under real-time MRI guidance i.e. capability of tracking the needle with higher accuracy and bandwidth than real-time MRI. Three fibers, each with three Fiber Bragg Gratings (FBG) were embedded into a 0.6 mm inner stylet of a 20G MRI-compatible biopsy needle. The(More)
SUMMARY This paper presents the research work on a 1 degree of freedom (DOF) force reflecting tele-micromanipulation system. This system enables a human operator to position remote objects very precisely having haptic feedback. The slave robot is a nano-positioning piezo-actuator with hysteretic dynamics. This intrinsic nonlinearity results in positioning(More)