RESUMO
Continuum dexterous manipulators (CDMs) are suitable for performing tasks in a constrained environment due to their high dexterity and maneuverability. Despite the inherent advantages of CDMs in minimally invasive surgery, real-time control of CDMs' shape during nonconstant curvature bending is still challenging. This study presents a novel approach for the design and fabrication of a large deflection fiber Bragg grating (FBG) shape sensor embedded within the lumens inside the walls of a CDM with a large instrument channel. The shape sensor consisted of two fibers, each with three FBG nodes. A shape-sensing model was introduced to reconstruct the centerline of the CDM based on FBG wavelengths. Different experiments, including shape sensor tests and CDM shape reconstruction tests, were conducted to assess the overall accuracy of the shape-sensing. The FBG sensor evaluation results revealed the linear curvature-wavelength relationship with the large curvature detection of 0.045 mm and a high wavelength shift of up to 5.50 nm at a 90° bending angle in both the bending directions. The CDM's shape reconstruction experiments in a free environment demonstrated the shape-tracking accuracy of 0.216 ± 0.126 mm for positive/negative deflections. Also, the CDM shape reconstruction error for three cases of bending with obstacles was observed to be 0.436 ± 0.370 mm for the proximal case, 0.485 ± 0.418 mm for the middle case, and 0.312 ± 0.261 mm for the distal case. This study indicates the adequate performance of the FBG sensor and the effectiveness of the model for tracking the shape of the large-deflection CDM with nonconstant-curvature bending for minimally invasive orthopedic applications.
RESUMO
We present an autonomous robotic spine needle injection system using fluoroscopic image-based navigation. Our system includes patient-specific planning, intra-operative image-based 2D/3D registration and navigation, and automatic robot-guided needle injection. We performed intensive simulation studies to validate the registration accuracy. We achieved a mean spine vertebrae registration error of 0.8 ± 0.3 mm, 0.9 ± 0.7 degrees, mean injection device registration error of 0.2 ± 0.6 mm, 1.2 ± 1.3 degrees, in translation and rotation, respectively. We then conducted cadaveric studies comparing our system to an experienced clinician's free-hand injections. We achieved a mean needle tip translational error of 5.1 ± 2.4 mm and needle orientation error of 3.6 ± 1.9 degrees for robotic injections, compared to 7.6 ± 2.8 mm and 9.9 ± 4.7 degrees for clinician's free-hand injections, respectively. During injections, all needle tips were placed within the defined safety zones for this application. The results suggest the feasibility of using our image-guided robotic injection system for spinal orthopedic applications.
RESUMO
This paper presents the development and experimental evaluation of an active steering hand-held robotic system for milling and curved drilling in minimally invasive orthopaedic interventions. The system comprises a cable-driven continuum dexterous manipulator (CDM), an actuation unit with a handpiece, and a flexible, rotary cutting tool. Compared to conventional rigid drills, the proposed system enhances dexterity and reach in confined spaces in surgery, while providing direct control to the surgeon with sufficient stability while cutting/milling hard tissue. Of note, for cases that require precise motion, the system is able to be mounted on a positioning robot for additional controllability. A proportional-derivative (PD) controller for regulating drive cable tension is proposed for the stable steering of the CDM during cutting operations. The robotic system is characterized and tested with various tool rotational speeds and cable tensions, demonstrating successful cutting of three-dimensional and curvilinear tool paths in simulated cancellous bone and bone phantom. Material removal rates (MRRs) of up to 571 mm3/s are achieved for stable cutting, demonstrating great improvement over previous related works.
