Farshid Alambeigi

Design and characterization of a debriding tool in robot-assisted treatment of osteolysis

This paper focuses on the design and quantitative characterization of a debriding tool integrated with a robotic system to treat osteolysis (bone degradation). Osteolysis typically occurs due to wear of the polyethylene liner of the acetabular implant after total hip replacement surgery. In less invasive treatment of osteolysis, surgeons conventionally use rigid tools to debride the lesion, however with these inflexible instruments, complex lesion shapes are not completely treatable (about 50%). To address this issue, we have developed a debriding tool that passes through the lumen of a continuum dexterous manipulator (CDM). Integration of the CDM with a robotic arm assists the surgeon to reach the desired region behind the implant. Performance of the debriding tool integrated with this system was quantitatively evaluated during a simulated robot-assisted lesion debriding scenario. Rotational speed, aspiration pressure and irrigation flow of the debriding tool, as well as the sweeping velocity of the robotic system were identified as effective parameters in this procedure. Results indicate that maximum efficiency of the tool is achievable in a particular combination of these parameters.

A continuum manipulator with phase changing alloy

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 for transitioning the phase changing alloy between stiff and compliant states. Single-segment and two-segment working prototypes of the CM are demonstrated. The mechanical and thermodynamic features of these prototypes are discussed and their physical performance is investigated. Advantages of the presented design with phase changing alloy include: significantly improved dexterity, high payload to weight ratio, controllable stiffness, energy efficiency, and a large lumen.

Control of the Coupled Motion of a 6 DoF Robotic Arm and a Continuum Manipulator for the Treatment of Pelvis Osteolysis

The paper addresses the coupled motion of a 6 degree of freedom robot and a snake-like dexterous manipulator (SDM) designed for the treatment of bone defects behind the implant during total hip arthroplasty revision surgery. We have formulated the problem as a weighted, multi-objective constraint, linear optimization. A remote center of motion (RCM) acts as a virtual constraint for the robot. The coupled robot kinematics does not assume piecewise-constant curvature for the SDM. We have evaluated our method by simulating the coupled system inside a potential lesion area.

A Curved-Drilling Approach in Core Decompression of the Femoral Head Osteonecrosis Using a Continuum Manipulator

In conventional core decompression of osteonecrosis, surgeons cannot successfully reach the whole area of the femoral head due to rigidity of the instruments currently used. To address this issue, we present design and fabrication of a novel steerable drill using a continuum dexterous manipulator (CDM) and two different flexible cutting tools passing through the lumen of the CDM. A set of experiments investigated functionality and efficiency of the curved-drilling approach and the flexible tools on simulated cancellous bone. Geometry of the cutter head, rotational and feed velocity of the tool, and pulling tension of the CDM cables have been identified as the effective curved-drilling parameters. Considering these parameters, we investigated drilling trajectory, contact force, and mass removal for various combinations of feed-velocities (0.05, 0.10, and 0.15 mm/s) and cable tensions (6, 10, 15, and 25 N) with constant rotational speed of 2250 r/min. Results show that: first, pulling tension of the cable is the most dominant parameter affecting the curved-drilling trajectory; and second, the proposed steerable drill is able to achieve 40° bend without buckling. Based on these results we developed a method for planning drill trajectories and successfully verified abilities for S-shape and multiple-branch drilling. The verification experiments were performed on both simulated and human cadaveric bones.

Toward robot-assisted hard osteolytic lesion treatment using a continuum manipulator

In this paper, we describe the design and fabrication of an actuation unit for controlling a continuum dexterous manipulator (CDM). The actuation unit is attached to a positioning robot and the integrated system provides sufficient dexterity for placement of a proposed flexible cutting tool used for treatment of oseteolysis (bone degradation). Preliminary experiments on simulated osteolytic lesions demonstrated the feasibility of using the novel flexible cutter inside the continuum manipulator. In these experiments, we found an optimal combination of rotational and sweeping speed of the cutter through the lesion. We also investigated the buckling of the flexible cutter during the cutting procedure.In this paper, we describe the design and fabrication of an actuation unit for controlling a continuum dexterous manipulator (CDM). The actuation unit is attached to a positioning robot and the integrated system provides sufficient dexterity for placement of a proposed flexible cutting tool used for treatment of oseteolysis (bone degradation). Preliminary experiments on simulated osteolytic lesions demonstrated the feasibility of using the novel flexible cutter inside the continuum manipulator. In these experiments, we found an optimal combination of rotational and sweeping speed of the cutter through the lesion. We also investigated the buckling of the flexible cutter during the cutting procedure.

FBG-based large deflection shape sensing of a continuum manipulator: Manufacturing optimization

Real-time large deflection sensing of continuum dexterous manipulators (CDM) is essential and challenging for many minimally invasive surgery (MIS) applications. To this end, the feasibility of using Fiber Bragg Grating (FBG) sensors to detect large CDM deflections was demonstrated. Previous studies by our group proposed attaching an FBG array along with two nitinol (NiTi) wires as substrates to form a triangular cross section capable of large deflection detection for a 35 mm CDM. The strenuous fabrication procedure, however, relies on trial and error to ensure accurate attachment of components. In this paper, we propose a novel design for assembling large deflection FBG sensors utilizing a custom-design three-lumen polycarbonate tube with circular cross section. The proposed design eliminates fabrication challenges by embedding the FBG array and NiTi wires inside the tube in a more robust, repeatable, time-efficient and cost-effective (compared to multicore fibers) manner. Calibration experiments of the sensor assembly alone and inside the CDM indicate consistent linear (R2∼0.99) wavelength-curvature relationship. Experimental results show 3.3% error in curvature detection.

Toward Semi-autonomous Cryoablation of Kidney Tumors via Model-Independent Deformable Tissue Manipulation Technique

We present a novel semi-autonomous clinician-in-the-loop strategy to perform the laparoscopic cryoablation of small kidney tumors. To this end, we introduce a model-independent bimanual tissue manipulation technique. In this method, instead of controlling the robot, which inserts and steers the needle in the deformable tissue (DT), the cryoprobe is introduced to the tissue after accurate manipulation of a target point on the DT to the desired predefined insertion location of the probe. This technique can potentially reduce the risk of kidney fracture, which occurs due to the incorrect insertion of the probe within the kidney. The main challenge of this technique, however, is the unknown deformation behavior of the tissue during its manipulation. To tackle this issue, we proposed a novel real-time deformation estimation method and a vision-based optimization framework, which do not require prior knowledge about the tissue deformation and the intrinsic/extrinsic parameters of the vision system. To evaluate the performance of the proposed method using the da Vinci Research Kit, we performed experiments on a deformable phantom and an ex vivo lamb kidney and evaluated our method using novel manipulability measures. Experiments demonstrated successful real-time estimation of the deformation behavior of these DTs while manipulating them to the desired insertion location(s).

A highly sensitive fiber Bragg Grating shape sensor for continuum manipulators with large deflections

Fiber Bragg Grating (FBG) sensors are proposed for medical applications, especially for shape sensing of continuum manipulators due to their numerous advantages over other types of sensors. In this paper, we design, fabricate, and evaluate a novel FBG sensor assembly addressing challenges associated with integration with continuum manipulators. Experimental results with the new FBG sensor demonstrated detection of small radii of curvatures (20 mm), high sensitivity (up to 8 nm wavelength shift in each direction of bend), and calibration repeatability (RMS error of 92 picometer) leading to a high signal to noise ratio for the proposed easy-to-fabricate sensor.