Yung-Ho Jo

An implementation of sensor-based force feedback in a compact laparoscopic surgery robot.

Despite the rapid progress in the clinical application of laparoscopic surgery robots, many shortcomings have not yet been fully overcome, one of which is the lack of reliable haptic feedback. This study implemented a force-feedback structure in our compact laparoscopic surgery robot. The surgery robot is a master-slave configuration robot with 5 DOF (degree of freedom corresponding laparoscopic surgical motion. The force-feedback implementation was made in the robot with torque sensors and controllers installed in the pitch joint of the master and slave robots. A simple dynamic model of action-reaction force in the slave robot was used, through which the reflective force was estimated and fed back to the master robot. The results showed the system model could be identified with significant fidelity and the force feedback at the master robot was feasible. However, the qualitative human assessment of the fed-back force showed only limited level of object discrimination ability. Further developments are underway with this result as a framework.

Development of an Implantable Intrathecal Drug Infusion Pump

An intrathecal drug infusion system has been designed, manufactured and tested. The system is composed of a drug reservoir and a pump/controller assembly. The drug reservoir made of SUS316L is a negative pressure gas chamber enclosing a bellows type drug chamber. The pump/controller assembly includes a bacterial filter, a controller circuit board, a battery and a micropump, and is connected to a catheter for intrathecal infusion. The micropump implements a peristaltic pumping of the drug by a sequential motion of three pairs of cam and cam-follower. In vitro performance tests were conducted with prototypes.

Micro Tube Pump for an Implantable Drug Infusion Device

This paper proposes a tube pump composed of small-sized cams and followers for an implantable intrathecal drug infusion device. Each followers is driven by a cam and liquid is discharged by a sequential reciprocal motion of the followers. The advantage of this structure is that it allows the pump to be clean and valveless. To design a small-sized, low power pump some analysis were performed to determine the design parameters of the cam, follower and the tube. To verify the feasibility of the experiment, a prototype was manufactured and its operating characteristics were investigated. Experimental results were in accordance with the expected results obtained from analysis.

Relationship Between Atrial Pressures and the Interventricular Pressure in the Moving Actuator Type Total Artificial Heart

The right and left atrial pressures are important parameters in the automatic control of a total artificial heart (TAH) within normal physiological ranges. Our TAH is composed of a moving actuator, right and left ventricles, and the interventricular space (IVS) enclosed by a semirigid housing. During operation of the TAH, the IVS volume is changed dynamically by the difference between the ejection volume of one ventricle and the inflow volume of the other. Therefore, the change in pressure of the IVS is related to both right and left atrial pressures. We measured the interventricular pressure (IVP) waveform using a pressure sensor and attempted to estimate indirectly the changes in atrial pressures. This method has the advantage that the sensor does not contact the blood directly. Furthermore, the IVP waveform has a zero baseline in each pump cycle, thus the pressure measurements are free from transducer drift problems because the peak pressure can be measured from these baseline values. From in vitro experiments, we found that the IVP waveform contained several useful parameters such as negative peak IVP value, dP/dton the initial break, and the area enclosed by the profile for each stroke, each of which are associated with the left and right atrial pressures and the filling conditions of the ventricles. The measured atrial pressures were linearly related to the negative peak value of the interventricular pressure.

Laparoscope Manipulator Control for Minimally Invasive Surgery

An efficient laparoscope manipulator robot was designed to automatically control the position of laparoscope via a passive joint on end-effector position. The end position of the manipulator is controlled to have corresponding velocity defined in the global coordinate space using laparoscopic visual information. Desired spatial position of laparoscope was derived from detected positions of surgical instrument tips, then the clinical viewing plane was moved by visual servoing task. The laparoscope manipulator is advantageous for automatically maintaining clinically important views in the laparoscopic image without any additional operator. A laparoscope is mounted to a holder which is linked to four degree of freedom manipulator via universal joint-type passive rings connection. No change in the design of laparoscope or manipulator is necessary for its application to surgery assistant robot system. Expanded working space and surgical efficiency were accomplished by implementing slant linking structure between laparoscope and manipulator. To ensure reliable positioning accuracy and controllability, the motion of laparoscope in an abdominal space through trocar was inspected using geometrical analysis. A designed laparoscope manipulating robot system can be easily set up and controlled in an operation room since it has a few subsidiary devices such as a laparoscope light source regulator, a control PC, and a power supply.

Development of an Implantable Drug Infusion Pump for Pain Control in Cancer Patients

This paper presents a implantable intrathecal drug infusion pump for pain control in cancer patients. This device consists of micropump module, drug reservoir module and control module. The micropump module using cam-follower mechanism composed of small-sized four cams and four followers. Each followers is driven by a cam and liquid is discharged by a sequential reciprocal motion of the followers. The advantage of this structure is that it allows the pump to be clean and valveless. The drug reservoir module composed of drug chamber, gas chamber and diaphragm. The control module composed of battery, wireless communication unit and controller. To design a small-sized, low power pump some analysis were performed to determine the design parameters. To verify the feasibility of the experiment, a prototype was manufactured and its operating characteristics were investigated. Experimental results were in accordance with the expected results obtained from analysis. 1. 서 론***

Development of a vision integration framework for laparoscopic surgical robot.

In order to realize intelligent laparoscopic surgical robot, a vision integrated system constitutes one of the fundamental components. The authors have constructed a vision framework in the current version of NCC (National Cancer Center) laparoscopic surgical robot controlled on a real-time OS (RTLinux-Pro, FSMLabs Inc., U.S.A.). Adding vision framework, we have been applying and testing image processing algorithms- edge detection of object for positioning surgical tool, Watersheds for recognizing object. This paper documents the implementation of the framework and preliminary results of the image segmentation using Watersheds algorithm. Finally the real-time processing capability of our vision system is discussed

Automatic Regulation of Output of an Electrohydraulic Left Ventricular Assist Device Using the Polymer Bellows Water Pressure and Motor Current

An electrohydraulically driven left ventricular assist device (LVAD) has been developed in our laboratory. Over years of in vitro and in vivo testing, a “suction” problem has been pointed out as one of the major problems related to the device mechanism. The suction problem involves collapse of the left atrium, which can be caused by excessive negative pressure generated by the active blood-filling mechanism, and can lead to damage to the atrium or an air-embolism. We have developed methods for properly controlling the assistance output, depending upon the inlet pressure conditions. Algorithms have been developed for setting an absolute limit to negative pressure and for the regulation of the diastolic velocity of the device. The regulating system is based on the estimation of left atrial pressure (LAP), using the internal pressure of the polymer bellows and the motor current as raw information indicating the status of the left atrium. The estimation is based upon direct analysis of the signal wave form, coupled with the use of fuzzy logic in determining significant parameters such as the systolic peak, diastolic peak, and diastolic integral. Results of experiments using a mock-circulation system have shown that the new control system performs satisfactorily in detecting suction. An animal experiment was conducted to verify the feasibility of the methods. In a 17-day experiment using an adult sheep with a left ventricular assist device, there was no sign of damage or suction-related problems when we used the new method for controlling the diastolic velocity depending upon the bellows water pressure. In this paper, the methods are described and the results are documented.