[Show abstract][Hide abstract] ABSTRACT: The surface shape and optical thickness variation of a lithium niobate (LNB) wafer were measured simultaneously using a wavelength-tuning interferometer with a new phase-shifting algorithm. It is necessary to suppress the harmonic signals for testing a highly reflective sample such as a crystal wafer. The LNB wafer subjected to polishing, which is in optical contact with a fused-silica (FS) supporting plate, generates six different overlapping interference fringes. The reflectivity of the wafer is typically 15%, yielding significant harmonic signals. The new algorithm can flexibly select the phase-shift interval and effectively suppress the harmonic signals and crosstalk. Experimental results indicated that the optical thickness variation of the LNB wafer was measured with an accuracy of 2 nm.
[Show abstract][Hide abstract] ABSTRACT: In phase shifting interferometry, the fringe contrast is preferred to be at a maximum when there is no phase shift error. In the measurement of highly-reflective surfaces, the signal contrast is relatively low and the measurement would be aborted when the contrast falls below a threshold value. The fringe contrast depends on the design of the phase shifting algorithm. The condition for achieving the fringe contrast maximum is derived as a set of linear equations of the sampling amplitudes. The minimum number of samples necessary for constructing an error-compensating algorithm that is insensitive to the jth harmonic component and to the phase shift error is discussed. As examples, two new algorithms (15-sample and (3N – 2)-sample) were derived that are useful for the measurement for highly-reflective surfaces.
[Show abstract][Hide abstract] ABSTRACT: The authors have developed a bed-type non-invasive ultrasound theragnostic system (NIUTS) that compen-sates for movement by tracking and following the area to be treated by stereo ultrasound imaging while irradiating high-intensity focused ultrasound (HIFU) onto the affected area. In this paper, we propose a novel robust template matching method to track and follow body targets, which include tumors and stones for the NIUTS. The proposed novel robust template matching method could be applied to a motion tracking of the real human kidney based on the ultrasound images, which is the first successful report as far as I know. This robust visual servoing method could be a great tool to treat the tumors and stones precisely and safely.
2014 IEEE Int. Conf. Robotics and Automation (ICRA 2014); 05/2014
[Show abstract][Hide abstract] ABSTRACT: In this paper, an improved mechanistic model is developed to predict the thrust force and torque for bone-drilling operation. The cutting action at the drill point is divided into three regions: the cutting lips, outer portion of the chisel edge (the secondary cutting edges), and inner portion of the chisel edge (the indentation zone). Models that account for the unique mechanics of the cutting process for each of the three regions are formulated. The models are calibrated to bovine cortical bone material using specific cutting pressure equations with modification to take advantage of the characteristics of the drill point geometry. The models are validated for the cutting lips, the chisel edge, and entire drill point for a wide range of spindle speed and feed rate. The predicted results agree well with experimental results. Only the predictions for the drilling torque on the chisel edge are lower than the experimental results under some drilling conditions. The model can assist in the selection of favorable drilling conditions and drill-bit geometries for bone-drilling operations.
[Show abstract][Hide abstract] ABSTRACT: Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is a promising biomaterial for use in dental and femoral implants. The current method for machining Y-TZP involves grinding after sintering. However, the grinding process is time consuming and therefore costly. To resolve these issues, this paper proposes a precision cutting process that utilizes a UV-laser-assisted machining method that requires no expensive cutting tools such as diamond tools. The UV laser is used to heat the Y-TZP, which improves its machinability. First, we performed experiments to determine that the most suitable machining temperature was 600 °C. A simulation was then used to determine the optimal distance between the tool edge and the laser spot. Finally, experiments using a UV laser were conducted to confirm the effectiveness of using a UV laser for machining. In these experiments, a Y-TZP sample was cut, and grooves were generated. The carved grooves were 20 mm long, 100 μm wide, and approximately 10 μm deep. Cutting without using a UV laser was also performed as a reference experiment. The results show that the use of the laser significantly decreased the number of large cracks from 14 to 3, the specific cutting energy by 35%, and the breakage of the tool edge. These results demonstrate the possibility of enhancing the productivity of Y-TZP products.
[Show abstract][Hide abstract] ABSTRACT: Forceps tracking is an important element of high-level surgical assistance such as visual servoing and motion analysis. This paper describes a robust, efficient tracking algorithm capable of estimating the forceps tip position in an image space by fusing visual tracking data with kinematic information. In visual tracking, the full-state parameters of forceps are estimated using the projective contour models of a 3-D CAD model of the forceps. The likelihood of the contour model is measured using the distance transformation to enable fast calculation, and the particle filter estimates the full state of the forceps. For more robust tracking, the result data obtained from visual tracking are combined with kinematic data that are obtained by forward kinematics and hand–eye transformation. The fusion of visual and kinematic tracking data is performed using an adaptive Kalman filter, and the fused tracking enables the reinitialization of visual tracking parameters when a failure occurs. Experimental results indicate that the proposed method is accurate and robust to image noise, and forceps tracking was successfully carried out even when the forceps was out of view.
IEEE/ASME Transactions on Mechatronics 01/2014; 19(1):278-288. · 3.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The thermally assisted machining of yttria-stabilized tetragonal zirconia polycrystal using a cutting tool heated with induction heating was proposed. Although the conventional thermally assisted machining cannot be applied to drilling, the proposed method can be. Heat transfer from the heated cutting tool to the workpiece was simulated analytically, and the result showed that heating of the tool up to 500 °C produced an increase of 150–400 °C in the workpiece temperature. Cutting experiments demonstrated an improvement in machinability.
[Show abstract][Hide abstract] ABSTRACT: In this paper, we propose a method for identifying systems incorporating a mechanical oscillation part for a non-invasive ultrasound theragnostic system(NIUTS). The NIUTS tracks and follows movement in an area requiring treatment (renal stones, in this study) by irradiating the area with high intensity focused ultrasound (HIFU). Blur noise caused by oscillation of the mechanical system adversely affects the servo performance. To solve this problem and enhance the servo performance, it is first necessary to identify those parts of the NIUTS system that incorporate a mechanical oscillation part. Secondly, we implemented a mechanical oscillation suppression filter based on the abovementioned method for identifying the mechanical oscillation part.
International Journal of Automation Technology (IJAT). 01/2014; 8(1):110-119.
[Show abstract][Hide abstract] ABSTRACT: A computer-assisted navigation system to be used for total knee arthroplasties (TKAs) was reported to improve the accuracy of bone resection and result in precise implant placement, but the concomitant surgical invasion and time consumption are clinical problems. We developed a computed tomography (CT)-based navigation system (NNS) to be used for minimally invasive TKA. It requires only the reference points from a small limited area of the medial femoral condyle and proximal tibia through a skin incision to obtain optical images. Here we evaluated the usefulness and accuracy of the NNS in comparison with the commercially available BrainLAB image-free navigation system (BLS). In a clinical experiment, the registration times obtained with the NNS tended to be shorter than those obtained with the BLS, but not significantly so. The NNS group tended to be in the extended position in the sagittal plane of the distal femur within 3 degrees, and the BLS group showed rather flexed deviation in the sagittal plane of the anterior femur.
[Show abstract][Hide abstract] ABSTRACT: During surgical interventions, bone tissue may be damaged by the achieved high cutting efforts and thermal damage, which should be avoided. In this study, a new surgical drill bit with two types of cutting edges is proposed and tested, reducing tissue damage. Large part of the material is removed by brittle crack propagation, and surface is finished precisely with small uncut chip thickness. Even if temperatures achieved in the bone are not reduced due to rubbing effects, lower cutting force and processing energy, and better surface roughness are obtained with the proposed tool compared to the conventional drill bit.
Materials and Manufacturing Processes 10/2013; 28:1065-1070. · 1.49 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The absolute optical thickness of a 140-mm2 mask blank glass plate 3.1 mm thickness was measured by three-surface interferometry using a wavelength-tuning Fizeau interferometer. The interference order was determined by the excess fraction method. The wavelength of a tunable laser diode was scanned linearly from 632 to 642 nm, and a CCD detector recorded 2000 interference images. Two kinds of optical thicknesses measured by discrete Fourier analysis and phase-shifting were synthesized to obtain the optical thickness with respect to the ordinary refractive index. The optical thickness defined by the group refractive index at the 637 nm central wavelength was measured by wavelength scanning. The optical thickness deviation defined by the ordinary refractive index was measured using tunable phase-shifting. The systematic errors caused by nonlinearity in the wavelength tuning were corrected through correlation analysis between the theoretical and observed interference fringes.
Optics and Lasers in Engineering 10/2013; 51(10):1173–1178. · 1.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have developed a thin needle driver with multiple degrees-of-freedom (DOFs) for neonatal laparoscopic surgery. The tip of this needle driver has three DOFs for grasp, deflection and rotation. Our aim was to evaluate the performance of the multi-DOF needle driver in vertical plane suturing.
Six pediatric surgeons performed four directional suturing tasks in the vertical plane using the multi-DOF needle driver and a conventional one. Assessed parameters were the accuracy of insertion and exit, the depth of suture, the inclination angle of the needle and the force applied on the model.
In left and right direction sutures, the inclination angle of the needle with the multi-DOF needle driver was significantly smaller than that with the conventional one (p = 0.014, 0.042, respectively). In left and right direction sutures, the force for pulling the model with the multi-DOF needle driver was smaller than that with the conventional one (p = 0.036, 0.010, respectively).
This study showed that multi-directional suturing on a vertical plane using the multi-DOF needle driver had better needle trajectories and was less invasive as compared to a conventional needle driver.
Pediatric Surgery International 08/2013; · 1.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract Aims: The aims of this study were to develop a thin needle driver with multiple degrees of freedom and to evaluate its efficacy in multidirectional suturing compared with a conventional needle driver. Materials and Methods: The tip (15 mm) of the novel user-friendly needle driver (3.5 mm in diameter) has three degrees of freedom for grasping, rotation, and deflection. Six pediatric surgeons performed two kinds of suturing tasks in a dry box: three stitches in continuous suturing that were perpendicular or parallel to the insertion direction of the instrument, first using the novel instrument, then using a conventional instrument, and finally using the novel instrument again. The accuracy of insertion and exit compared with the target points and the procedure time were measured. Results: In the conventional and novel procedures the mean gaps from the insertion point to the target in perpendicular suturing were 0.8 mm and 0.7 mm, respectively; in parallel suturing they were 0.8 mm and 0.6 mm, respectively. The mean gaps from the exit point to the target in perpendicular suturing were 0.6 mm and 0.6 mm for conventional and novel procedures, respectively; in parallel suturing they were 0.6 mm and 0.8 mm, respectively. The procedure time for perpendicular suturing was 33 seconds and 64 seconds for conventional and novel procedures, respectively (P=.02); for parallel suturing it was 114 seconds and 91 seconds, respectively. Conclusions: Our novel needle driver maintained accuracy of suturing; parallel suturing with the novel driver may be easier than with the conventional one.
[Show abstract][Hide abstract] ABSTRACT: The interference fringe order of a transparent glass plate was determined using a three-surface wavelength-tuning Fizeau
interferometer and an excess fraction method. We employed multiple-surface interferometry considering the potential for
simultaneous measurement of the surface shape and geometric thickness. The optical thickness signal was separated
from the three interference signals in the frequency space. A frequency selective phase-shifting algorithm and a discrete
Fourier analysis detected the phase of the modulated interference fringes. The optical thickness obtained by wavelengthtuning
Fizeau interferometry is related to the group refractive index. In contrast, the optical thickness deviation obtained
by the phase-shifting technique is related to the ordinary refractive index. These two kinds of optical thicknesses were
synthesized with the help of the dispersion relation of a fused-silica glass. Finally, the interference fringe order was
determined using an excess fraction method that could eliminate the initial uncertainty of the refractive index.
[Show abstract][Hide abstract] ABSTRACT: Surgical needle tracking is an important element of high-level automated operations conducted by surgical robotic systems. However, conventional needle tracking algorithms lack robust performance with different needle postures and are not applicable to the small needles used during microsurgery. This paper discusses a robust, efficient needle tracking algorithm, which is capable of estimating all of the positions and of the postures of a microsurgical needle. In the preoperative preparation stage, contour models of the microsurgical needle are generated using a 3-D CAD model and saved in a database. During the operation, the system extracts the contours of the microsurgical needle from the microscopic image using the edge and the color information. The system then calculates the likelihood of the contour models in the database by matching the contours extracted from the microscopic image. The experimental results indicated that our proposed method has high accuracy when tracking a microsurgical needle, and that it performed robustly with different needle postures.
Control, Automation and Systems (ICCAS), 2013 13th International Conference on; 01/2013
[Show abstract][Hide abstract] ABSTRACT: In orthopedic operations, no sound solutions exist to avoid conditions like tool breakage, bone fracture/cracks and thermal necrosis for lacking understanding of the mechanics of the bone cutting process. In this work, analysis of variance (ANOVA) and regression analysis were performed to investigate effects of cutting conditions on cutting and thrust forces based on a full factorial design. Then applicability of Merchant's analysis for calculating cutting force with respect to rake angle and feed was evaluated by comparison with experiments. Finally, the friction coefficient was evaluated by calculation. ANOVA shows that forces are much more sensitive to feed, cutting direction and rake angle than to cutting speed. Regression equations including all four factors were obtained by introduction of dummy variables. Cutting forces from experiments and from Merchant's analysis are partially comparable (maximum relative error = 34%) when feed and rake angle are changed. Friction coefficient was affected by rake angle and cutting direction. Cutting speed had little effect on the coefficient. These results can deepen the understanding of the mechanics of the bone-cutting process and assist the development of innovative cutting devices and selection of favorable cutting conditions for the procedure.
Machining Science and Technology 01/2013; 17(4). · 0.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This paper reports fabrication of retinal microvessels model for evaluation of microcannulation. Because microcannulation as a new treatment for retinal vein occlusion is difficult surgery operation, development and evaluation of microsurgical robot systems to assistant vitreoretinal surgery is needed. Evaluation of microcannulation needs a retinal microvessels model without individual difference. Therefore, we fabricated artificial microvessel models with the scale and the cross-sectional shape simulating the actual vascular by using the micro-nano-processing technology.
Micro-NanoMechatronics and Human Science (MHS), 2013 International Symposium on; 01/2013
[Show abstract][Hide abstract] ABSTRACT: Loss of haptic sensation in a master-slave system is one of the open problems in robotic surgery, and recognition of surgical situations through haptic sensation is a challenge. In this paper we propose an autonomous risk-detection system for a master-slave surgical robotic system in order to estimate a property of an object (i.e., contact impedance) using a force sensor mounted on a surgical robotic instrument. The system autonomously detects the risk based on the estimated contact impedance and accordingly activates the motion at the slave unit as well as the force feedback at the master unit. We implemented the proposed method in a teleoperated master-slave system to detect the perforation risk of a membranous object. The performance of the system was evaluated through experiments. The classification accuracy for perforation risk was about 98.5 % in fourfold cross-validation. The experiments verified that the risk detection system accurately detected the perforation risk and improved the safety of the master-slave system.
Intelligent Robots and Systems (IROS), 2013 IEEE/RSJ International Conference on; 01/2013