A novel tactile probe with medical and surgical applications

Purpose The paper aims to discuss design, fabrication, testing and simulation of a novel tactile probe used for measuring the stiffness of biological soft tissues/materials with a view to medical and surgical applications. Design/methodology/approach Both finite element modeling and experimental approach were used in this research. The novel tactile probe capable of recording force-deformation feedback is accompanied with the tactile-status-display which is a custom-designed user-friendly interface. This system can evaluate the stiffness in each part of force-deformation status. Findings The new system named novel tactile probe was fabricated, and the results on artificial materials (with different stiffnesses) and the sheep kidney (containing a hard object) were reported. Recording different stiffnesses, detecting hard object embedded in soft tissue and predicting the exact location of it are the main results that have been extracted through the diagrams obtained by the novel tactile probe system. Research limitations/implications The designed and fabricated system can be modified and miniaturized to be used during different minimally invasive surgeries in the future. Practical implications The most distinguishing feature of this novel tactile probe is its applicability during different laparoscopic surgeries, so the in vivo data can be obtained. Originality/value For the first time, a tactile probe has been designed and tested in the form of laparoscopic instrument which upgrades the efficiency of available laparoscopic instruments. Also, the novel tactile probe can be used in both in vivo and in vitro experimental setups for measuring the stiffness of sensed objects.

Optical Tracking of a Tactile Probe for the Reverse Engineering of Industrial Impellers

Different sensor technologies are available for dimensional metrology and reverse engineering processes. Tactile systems, optical sensors, and computed tomography (CT) are being used to an increasing extent in various industrial contexts. However, each technique has its own peculiarities, which may limit its usability in demanding applications. The measurement of complex shapes, such as those including hidden and twisted geometries, could be better afforded by multisensor systems combining the advantages of two or more data acquisition technologies. In this paper, a fully automatic multisensor methodology has been developed with the aim at performing accurate and reliable measurements of both external and internal geometries of industrial components. The methodology is based on tracking a customized hand-held tactile probe by a passive stereo vision system. The imaging system automatically tracks the probe by means of photogrammetric measurements of markers distributed over a plate rigidly assembled to the tactile frame. Moreover, the passive stereo system is activated with a structured light projector in order to provide full-field scanning data, which integrate the point-by-point measurements. The use of the same stereo vision system for both tactile probe tracking and structured light scanning allows the two different sensors to express measurement data in the same reference system, thus preventing inaccuracies due to misalignment errors occurring in the registration phase. The tactile methodology has been validated by measuring primitive shapes. Moreover, the effectiveness of the integration between tactile probing and optical scanning has been experienced by reconstructing twisted and internal shapes of industrial impellers.

Property Evaluation of Eccentric Astigmatic Method to Apply Micro Tactile Probe

Displacement detection of a small sphere with high sensitivity is required for realizing the micro tactile probe used in micro-coordinate-measuring machines (CMMs). Therefore, the authors have proposed a new technique for detecting the three-dimensional displacement of a small sphere by a kind of astigmatic method, termed the “eccentric astigmatic method (EAM).” In the EAM, a spherical mirror as a spherical tactile probe is placed on the focus of an objective lens. At this position, three eccentric beams, focused by the objective lens, are incident on the mirror surface at right angles and the reflected rays return on the incident paths. In contrast, when the sphere moves from this position even by a small distance, the return path of each reflected ray changes drastically. This change can be detected by the EAM using a condenser lens and a photodetector. The changes in the spot radius caused by the EAM were calculated using a ray-tracing code. As a result, a change in the spot shape was found to occur only for displacement along one axis. Moreover, simulations based on wave optics were performed, whose results confirmed the feasibility of detection of the three-dimensional displacement of a sphere by the EAM.