N.K. Mehta

Design and Development of In Vivo Robot for Biopsy

In vivo robot is an emerging medical technology that could greatly help biopsy and surgery. This paper proposes to design and develop a miniature in vivo robot for biopsy as an add-on to the current endoscope. To allow more dexterity and flexibility, a four degree of freedom (DOF) robot manipulator is proposed. Accordingly, a wire actuated robot with articulated links like in a snake robot has been conceptualized. The robot was mathematically modeled and designed. To test the design, a 4-scaled aluminum model was manufactured. The kinematics of the model is verified experimentally. The four degree of freedom of the miniature robot are: a linear motion of the flexible shaft (first DOF); an axial rotation of the flexible shaft (second DOF); planar through differential wire movement (third DOF); and a combined wire motion for clipper action to take biopsy (fourth DOF). The proposed robot manipulator was modeled in SolidWorks and the kinematic and dynamic analysis was performed using the Robotics Toolbox in MATLAB.

Forward kinematic analysis of in-vivo robot for stomach biopsy

The introduction of robotic medical assistance in biopsy and stomach cavity exploration is one of the most important milestones in the field of medical science. The research is still in its infancy and many issues like limitations in dexterity, control, and abdominal cavity vision are the main concerns of many researchers around the globe. This paper presents the design aspects and the kinematic analysis of a 4 degrees of freedom (DOF) hyper-redundant in-vivo robot for stomach biopsy. The proposed robot will be inserted through the tool channel of a conventional 4-DOF endoscope and this will increase the dexterity and ease in reaching the furthest parts of the stomach beyond the duodenum. Unlike the traditional biopsy tool, the present design will enhance dexterity due to its 4 DOF in addition to the endoscope’s DOF. The endoscope will be positioned at the entrance to the stomach in the esophagus and the robot will move to the desired position inside the stomach for biopsy and exploration. The current robot is wire-actuated and possesses better maneuverability. The forward kinematic analysis of the proposed robot is presented in this paper.

Mixture D-Optimal Desing of Electrolyte Composition in ECH of Bevel Gears

In Electrochemical Honing (ECH), most of the metal is removed by electrolytic dissolution and therefore, the electrolyte composition plays a crucial role in the study. This paper presents the experimental investigation to find out the optimal electrolyte composition in improving surface quality of gear teeth profile during surfacing finishing of bevel gears by ECH process. In this study, mixture of sodium chloride and sodium nitrate in different ratios were used as input parameter and the percentage improvement in bearing ratio of gear teeth profile was used as response parameters while the experimental runs were designed and planned according to the Mixture D-Optimal design. Analysis of variance was carried out and optimal electrolyte composition was investigated to conduct the confirmation experiment.

Study of electrochemical-mechanical finishing of bevel gears

This study discusses the performance assessment of high precision finishing of bevel gears by electrochemical-mechanical finishing (ECMF) process. In the present study, experimental investigation has been carried out on an indigenously developed experimental setup for ECMF of bevel gears of AISI 1040 steel to evaluate the process capability in improving the surface quality of gear teeth profile. Surface integrity of ECMFed surface was analysed and it was found that the process has capability to enhance the surface quality of gear teeth profile by minimising the irregularities. The emphatic features of the newly developed experimental setup have also been discussed.

Machinability Studies in Hot Machining of Ti-6Al-4V Alloy

This work presents the influence of workpiece preheat temperatures on the machinability of Ti-6Al-4V alloy and chip formation. Machinability has been studied in terms of cutting forces, surface roughness and tool wear. Influence of preheat temperatures on chip morphology and roughness of chip back surface has been studied using scanning electron microscope and atomic force microscope respectively to get better insight of tribology at tool-chip interface. Based on overall observations, preheat temperature of 300 0C was found as the most appropriate parameter.

Inverse kinematics and control of 4-degree-of-freedom wire-actuated in vivo robot

Endoscopes have been in use for many clinical procedures including biopsy and limited surgery. A biopsy is one of its most common applications. For more than a decade, research is in continuation on various limitations encountered by surgeons in this area like dexterity, manoeuverability and controlling of the scope tip to bring it to an exact point of interest. Existing endoscopes have limitations in number of degrees of freedom. To counter this problem, a 4-degree-of-freedom in vivo robot has been proposed by the authors earlier. This article presents an inverse kinematic solution of the wire-actuated in vivo robot for trajectory control. For this, a kinematic analysis has been performed and the tip positions were obtained analytically. For a known tip position, the length of the wire to be wrapped and un-wrapped is decided from the relational approach and accordingly the desired pulley rotation is performed using the proportional–derivative controller. Simulations have been carried out for three different cases and satisfying results were obtained.

Modelling and experimental study of chip serration frequency in dry turning of Ti-6Al-4V alloy

This paper presents the investigation on the effects of cutting speed, feed rate and depth of cut on chip serration frequency in dry turning of Ti-6Al-4V alloy. The chip serration frequency plays a vital role in determining the machinability of this alloy as the serrated chips are observed at low cutting speed. Serrated chip formation causes a cyclic variation of cutting forces and often leads to serious vibrations resulting in chatter. The chip serration frequency is calculated by the distance between two consecutive shearing planes. Using the results of experiments, a regression model has been developed for chip serration frequency. Based on analysis of variance at 95% confidence interval the model is found to be highly significant. Cutting speed is found to be the most significant factor affecting the chip serration frequency. The effect of feed rate is much less and that of the depth of cut is insignificant.

Prediction of surface roughness using cutting parameters and vibration signals in minimum quantity coolant assisted turning of Ti-6Al-4V alloy

In this work, an attempt has been made to investigate the role of vibration signals in prediction of surface roughness in minimum quantity coolant assisted turning of Ti-6Al-4V alloy. Initially, a model of surface roughness as a function of cutting parameters was developed to serve as the reference data. Subsequently, two more models were developed - one representing the variation of surface roughness with the vibration and the other represents the variation of surface roughness as a function of cutting parameters and vibration signal considered in tandem. A comparison of the three models established that the model based on simultaneous consideration of cutting parameters and vibration was the most accurate of the three.

Machining with minimum quantity lubrication: a step towards green manufacturing

Increased cost associated with the use of coolant in machining operations, increased environmental awareness, and strict protection laws and health regulations for occupational safety demanded elimination/reduction of cutting fluids in metal cutting operations. Minimum quantity lubrication (MQL)/near dry machining (NDM), which relies on total use without residue has been gaining popularity as a new alternative for flood cooling. The quantity of cutting fluid in MQL is in ml/hr instead of in l/min as in flood cooling. The paper begins with an overview regarding the problems associated with the use of conventional flood cooling method leading to the need of MQL, and subsequently discusses the components and working principle of MQL system. The literature related to turning and milling operations has been reviewed and presented in two major headings: effect of operating parameters on MQL performance and effect of MQL on machinability to provide a clear and complete understanding of the system.

Bond graph modelling of in vivo robot for biopsy

Abstract Endoscopes have been in use for many procedures including limited surgery. And biopsy is one of its very common applications. Existing endoscopes have limitations in number of degrees of freedom. This paper presents a new design of In- Vivo robot. The work presents bond graph model of a robot for taking a biopsy sample inside the stomach. To develop the bond graph model a kinematic analysis is carried out and various transformer modulli required for drawing of bond graph model are evaluated. The developed bond graph model can be used for trajectory or force control of in vivo robots.