Author: ravikiranramesh

Distortion Invariant Joint-Feature for Visual Tracking in Catadioptric Omnidirectional Vision

  By

Abstract

Central catadioptric omnidirectional images exhibit serious nonlinear distortions due to quadratic mirrors involved. Conventional visual features developed based on the perspective model are hard to achieve a satisfactory performance when directly applied to the distorted omnidirectional image. This paper presents a parameterized neighborhood model to efficiently calculate the adaptive neighborhood of an object based on the measurable radial distance in image plane. On the basis of the parameterized neighborhood model, a distortion invariant joint-feature framework implemented with contour-color fragment mixture model of Gaussian is proposed for visual tracking in catadioptric omnidirectional camera system. Under the framework of Gaussian Mixture Model, the problem of feature matching is converted into feature clustering. A weight contribution mechanism is presented to flexibly weight the fragments based on their responses, which makes the system robustly guided by limited visible fragments even when serious partial occlusion happens. The experiments validate the performance of the proposed algorithm.

full text

Optimal teleoperation control of a constrained tendon-driven serpentine manipulator

  By

Abstract

In this paper, optimal remote control strategies to a novel master-slave flexible manipulator (FM) are presented. The system contains a constrained tendon-driven serpentine manipulator (CTSM), the base platform, a microcontroller, a PC and the Novint Falcon haptic input device. The bending of the CTSM backbone is controlled by the tendons and the length of the bending section is controlled by a constraint tube. Compared with other FMs, the CTSM has an improved workspace and dexterity. The CTSM is controlled using the Novint Falcon haptic input device, and two remote control modes are implemented, one is direct mapping and the other is incremental mode. Two optimal remote control strategies are proposed for the CTSM, i.e., highest stiffness and minimal movement. Experimental results show that the direct mapping is appropriated for fast movements and the incremental mode is adequate for accurate tasks. In combination with the optimal control strategies, a set of different applications for the CTSM are presented.

full text

Design of a Novel Flexible Endoscope – Cardioscope

  By

Abstract

In this paper, we present a novel flexible endoscope (FE) which is well suited to minimally invasive cardiac surgery (MICS). It is named the cardioscope. The cardioscope is composed of a handle, a rigid shaft, a steerable flexible section, and the imaging system. The fexible section is composed of an elastic tube, a number of spacing disks, a constraint tube, and four wires. It employs the constrained wire-driven fexible mechanism (CWFM) with a continuum backbone, which enables the control of both the angulation and the length of the flexible section. Compared to other endoscopes, e.g., rigid endoscope (RE) and fixed-length FE, the cardioscope is much more dexterous. The cardioscope can bend over 180 deg in all directions, and the bending is decoupled from the distal tip position. Ex vivo tests show that the cardioscope is well suited to MICS. It provides much wider scope of vision than REs and provides good manipulation inside confned environments. In tests, the cardioscope successfully explored the full heart through a single hole, which shows that the design is promising. Despite being designed for MICS, the cardioscope can also be applied to other minimally invasive surgeries (MISs), such as laparoscopy, neurosurgery, transnasal surgery, and transoral surgery.

full text

Kinematic Analysis and Motion Control of Wheeled Mobile Robots in Cylindrical Workspaces

  By

Abstract

Wheeled mobile robots (WMRs) are often used for maintenance of round pipes or ducts, which can typically be represented as a cylindrical workspace. Working in round pipes or ducts, kinematic models of WMRs are different from those applying on a plane and thus pose significant challenges in terms of kinematic analysis and motion control. To address these challenges, the kinematic properties of WMRs in a cylindrical workspace are analyzed in this paper. First, we discuss the kinematic properties of a single wheel in a cylindrical workspace. Then, we analyze the geometric constraints of WMRs in round pipes or ducts with analytical geometry. Based on these analyses, kinematic properties of WMRs in cylindrical workspaces are discussed with screw theory. A control law based on biaxial clinometer information is proposed, and it enables the robot to move horizontally in round pipes or ducts. Finally, the motion of a single wheel purely rolling in a cylindrical workspace is simulated. Experiments using a car-like mobile robot moving in round ducts are carried out to show the feasibility of the proposed algorithm.

full text

Condition Monitoring for Image-Based Visual Servoing Using Kalman Filter

  By

Abstract

In image-based visual servoing (IBVS), the control law is based on the error between the current and desired features on the image plane. The visual servoing system is working well only when all the designed features are correctly extracted. To monitor the quality of feature extraction, in this paper, a condition monitoring scheme is developed. First, the failure scenarios of the visual servoing system caused by incorrect feature extraction are reviewed. Second, we propose a residual generator, which can be used to detect if a failure occurs, based on the Kalman filter. Finally, simulation results are given to verify the effectiveness of the proposed method.

full text

Prototype Development of a Hand-Held Robotic Light Pipe for Intraocular Procedures

  By

Abstract

Light pipe is a tool providing illumination for delicate operations inside the eyeball in an eye surgery. Traditional light pipes with straight shafts have to be reoriented in order to enlarge its illustration range, which implies more risk of damage to the sclera and requires greater operation space for the handle. In order to overcome these limitations, this paper has proposed a novel robotized handheld light pipe based on concentric tubular structure. Tube parameters are selected based on the anatomical dimension of eyeballs. Novel actuation designs are described to meet the requirements of the intraocular procedures. An intuitive control scheme is implemented to facilitate surgeons’ operations. Furthermore, the benefit of the precurved tube compared with that of a straight tube is evaluated through experiments. It has been demonstrated that the proposed design as a light pipe holds the promise of enhancing intraocular surgeries.

full text

Motion planning of continuum tubular robots based on features extracted from statistical atlas

  By

Abstract

Continuum tubular robots, which are constructed by telescoping pre-curved elastic tubes, are capable of balancing the force application and steerability during minimally invasive surgeries. These devices are able to reach the desired surgical sites in body cavities without colliding with critical blood vessels, nerves and tissues. However, the motion planning of continuum tubular robots is quite challenging because of their complicated kinematics as well as the high dimensional configuration space. In this paper, a sampling-based motion planning method is proposed based on the Rapidly-exploring Random Tree (RRT) algorithm for continuum tubular robots in 3D environments, such as medullary cavities. The proposed motion planner enables a continuum tubular robot to maneuver roughly along the central axis of the statistical humerus atlas in an approximate follow-the-leader manner. The experiment results have demonstrated the effectiveness and superiority of the proposed motion planning algorithm.

full text

Hierarchical Recognition System for Target Recognition from Sparse Representations

  By

Abstract

A hierarchical recognition system (HRS) based on constrained Deep Belief Network (DBN) is proposed for SAR Automatic Target Recognition (SAR ATR). As a classical Deep Learning method, DBN has shown great performance on data reconstruction, big data mining, and classification. However, few works have been carried out to solve small data problems (like SAR ATR) by Deep Learning method. In HRS, the deep structure and pattern classifier are combined to solve small data classification problems. After building the DBN with multiple Restricted Boltzmann Machines (RBMs), hierarchical features can be obtained, and then they are fed to classifier directly. To obtain more natural sparse feature representation, the Constrained RBM (CRBM) is proposed with solving a generalized optimization problem. Three RBM variants, L 1 -RNM, L 2 -RBM, and L 1 / 2 -RBM, are presented and introduced to HRS in this paper. The experiments on MSTAR public dataset show that the performance of the proposed HRS with CRBM outperforms current pattern recognition methods in SAR ATR, like PCA + SVM, LDA + SVM, and NMF + SVM.

full text

Model-free Image Guidance for Intelligent Tubular Robots with Pre-clinical Feasibility Study: Towards Minimally Invasive Trans-orifice Surgery

  By

Abstract

Comprised of multiple curved concentric tubes, continuum tubular robots are capable to reach surgical targets while bypassing critical anatomical obstacles during minimally invasive surgeries, such as transnasal and transoral surgeries. To automatically track the surgical target and compensate undesired disturbance, an eye-in-hand image-based visual servo algorithm is presented in this paper to control in-house continuum tubular robots. The proposed visual servoing approach does not require any prior knowledge of kinematic models of the robots in order to avoid the errors introduced by imaging-sensor calibration and 3D position reconstruction. Preclinical cadaveric experiments have been demonstrated in the paper to illustrate the feasibility of the model-free automatic visual serving method

full text