15 accepted papers
This letter outlines the modelling, design, and experimental validation of a novel power-efficient actuator for an active ankle-foot orthosis (AAFO). The actuator is based on a new principle of discrete non-linear stiffness. Two or more linear springs are discretely compressed at specified displacem
Percutaneous Nephrolithotomy (PCNL) is the leading intervention for removing large or irregularly shaped kidney stones. It involves gaining access to the kidney through a small incision in the patient's back, through which a nephroscope is steered towards the stones. Despite decades of clinical prev
Series elastic actuators with passive compliance have been gaining increasing popularity in force-controlled robotic manipulators. One of the reasons is the actuator's ability to infer the applied torque by measuring the deflection of the elastic element as opposed to directly with dedicated torque…
Series elastic actuators have proven to be an elegant response to the issue of safety around human-robot interaction. The compliant nature of series elastic actuators provides the potential to be applied in robot-aided rehabilitation for patients with upper and lower limb musculoskeletal injuries. T…
Stability and transparency are key design requirements in haptic devices. Transparency can be significantly improved by replacing conventional electric motors with passive actuators such as brakes or dampers. Passive actuators can display a wide range of impedance and since they can only dis-sipate…
Needle deflection during certain minimally invasive percutaneous procedures, such as prostate biopsy or brachytherapy, is undesired and can be reduced through the use of feedback control. This letter uses a depth-dependent reduced-order three-dimensional (3-D) nonholonomic model of needle tip motion
In this letter, we present a model for needle deflection estimation in soft tissue. The needle is modelled as a vibrating compliant cantilever beam that experiences forces applied by the tissue as it is inserted. Each of the assumed vibration modes are associated with a weighting coefficient whose m
In percutaneous needle insertions, cutting forces at the needle tip deflect the needle and increases targeting error. Thus, modeling needle-tissue interaction in biological tissue is essential for accurate robotics-assisted needle steering. In this letter, dynamics of needle tip interaction with inh
Brachytherapy is a cancer treatment procedure where long needles are inserted toward an inner body target in order to deliver radioactive seeds that treat the cancer cells. Controlling the trajectory of the needle is very challenging as it deviates from a straight path during insertion. In this lett
This letter represents a sliding-based controller for steering beveled-tip needles to stationary locations in soft tissue in a 2-D environment by performing appropriate switches of bevel orientation by 180° axial rotations while the needle is being inserted. Assuming the rotation velocity to be larg
This paper introduces an automatic method to visualize 3D needle shapes for reliable assessment of needle placement during needle insertion procedures. Based on partial observations of the needle within a small sample of 2D transverse ultrasound images, the 3D shape of the entire needle is reconstru…
In needle-based medical procedures, beveled-tip flexible needles are steered inside soft tissue with the aim of reaching pre-defined target locations. The efficiency of needle-based interventions depends on accurate control of the needle tip. This paper presents a comprehensive mechanics-based model…
A tissue-independent model to estimate needle deflection during insertion in soft tissue is presented in this paper. A force/torque sensor is connected to the needle base in order to measure forces and moments during insertion due to needle deflection. A static mechanical model, which is based on th…
This paper represents an extension to the kinematic bicycle model for beveled-tip needle motion in soft tissue, which accounts for non-constant curvature paths for the needle tip. For a tissue that is not stiff relative to the needle, the tissue deformation caused by needle insertion deviates the ne…
We propose a method to estimate the entire shape of a long flexible needle, suitable for a needle insertion assistant robot. This method bases its prediction on only a small segment of a needle, imaged via ultrasound, after insertion. An algorithm is developed that can segment a needle observed part…