Kouhei Ohnishi

Improvement of Tactile Sensation of a Bilateral Forceps Robot by a Switching Virtual Model

Interest in tele-operation started many decades ago. Today, tele-operation is becoming a reality with improved tele-communication systems. Bilateral control is also a subset of tele-operation. Usually in bilateral control, force position information is exchanged between a master and a slave. This structure successfully transmits tactile sensation from the slave environment to the master operator. A bilateral control system is capable of transmitting tactile sensation to the master side. This capability is also known as the transparency of the system. If bilateral control is used in a surgery, ideally the medical doctor should sense the feeling coming from the body tissue together with the reaction force of the special surgical tool. We have previously proposed a method to eliminate the special surgical tool with a simple tool tip and a virtual tool model. However, a physical tool as well as the proposed virtual tool add impedance to the system. Even if a virtual model is used, impedances are essential to carry out the tool action. In this paper, a novel method is proposed to switch off and on the virtual tool model when the tool action can be replaced by the environmental reaction forces. An experiment was carried out using a bilaterally controlled forceps robot. Results show the applicability of the idea.

Tactile sensation improvement of a bilateral forceps robot with a switching virtual model

Interest of tele-operation started many decades ago. In day today lives tele-operation is getting a reality with improved tele-communication systems. Bilateral control is also a subset of tele-operation. Usually in bilateral control, force position information is exchanged between master and slave. This structure successfully transmits tactile sensation from the slave environment to the master operator. Good bilateral system is capable of transmitting tactile sensation to the master side. This capability is also known as the transparency of a system. If bilateral control is used in a surgery, ideally the doctor should feel the feeling coming from the body tissue together with the reaction force of the special surgical tool. We proposed |6], [7] a method to eliminate the special surgical tool with a simple tool tip and a virtual tool model. However, physical tool as well as the proposed virtual tool, add impedance to the system. Even if virtual model is used, impedances are essential to carry out the tool action. In this paper a novel method is proposed to switch off and on the virtual tool model when the tool action can be replaced by the environmental reaction forces. Experiment was carried out using a bilaterally controlled forceps robot. Results show the applicability of the idea.

Traction force improvement of a two wheel mobile manipulator by changing the centre of gravity

In this paper, a traction control method for a two wheel mobile robot is presented. Traction force acting on a wheel is dependent upon the dynamic frictional coefficient and the reaction force acting on each wheel, it is proposed to obtain the maximum traction force by selecting the best value for slip percentage as well as selecting a suitable value for the reaction force. Reaction force variation is achieved by changing the centre of gravity (COG) of the mobile robot. Two electric motors are used to drive the two wheel manipulator.

Implementation of pedal feeling for Brake By Wire system using bilateral control

Brake-by-wire means that the direct mechanical link between brake pedal and braking cylinder is completely replaced by an electromechanical braking system. This concept, originally used for aircraft and military only, has distinct advantages for implementing in new car designs. However brake pedal feeling should be identical to the conventional brake pedal. Ideally, the pedal should behave like a conventional brake. Bilateral control is proposed to be used to for brake by wire system. In conventional brake system, a physical spring is used to move the pedal to its ldquopedal parking positionrdquo. In this study, this spring is replaced by a virtual spring. Virtual spring damper model is used within the bilateral control system. Experiment uses a bilateral controlled master slave system. Even though this experiment system is not a brake by wire system, this bilateral system is capable enough to show the applicability of the proposed concept. Braking feeling could be transferred from the slave side to the pedal. Virtual spring behaved identically to a physical spring.

Realization of Virtual Slave Model of a Forceps Robot Using Bilateral Control

Bilateral control enables the operator to be placed away from the working environment. Slave manipulator usually works in a remote site or in a hazardous environment. Master operator is sensing the environment through the slave manipulator. Bilateral control can also be used in surgeries. Usually doctors are very sensitive to the tactile sensation they feel through medical tools. If bilateral control is used in surgery, ideally doctor should feel the feeling of the body tissue and the reaction force from the specialized tool. In this paper bilateral control is implemented for a forceps robot. Virtual spring acting on the end of the forceps is implemented to the bilateral control so that operator at the master side could feel the spring feeling together with the environment

Realization of Virtual Master Manipulator Using Bilateral Control

Bilateral control has been widely used in many industries including medical surgery. Slave manipulator usually works in a remote site or in a hazardous environment. Master operator is sensing the environment through the slave manipulator. Usually doctors are very sensitive to the tactile sensation they feel through medical tools. If bilateral control is used in surgery, ideally doctor should feel the feeling of the body tissue and the reaction force from the specialized tool. In this paper specialized tool is replaced by a virtual model.

Bilateral Control interacting with a Virtual Model and Environment

Bilateral control enables the operator to be placed away from the working environment. Slave manipulator usually works in a remote site or in a hazardous environment. Master operator is sensing the environment through the slave manipulator. Usually if scaling is not used, master operator could feel the slave environment as it is. If the master operator should feel a feeling other than that is coming from the slave, a virtual model can be used to modify the feeling. Even though this concept can be used in many industrial applications, bilateral forceps robot is used to prove its applicability. If bilateral control is used in a surgery, ideally doctor should feel the feeling of the body tissue and the reaction force from the specialized tool. Virtual spring acting at the end of the forceps is implemented to the bilateral control so that operator at the master side could feel the spring feeling together with the environment. Reaction torque observer is used as the method of measuring the reaction force. Virtual model is inserted in-between the disturbance observer inputs so that the virtual model together with the environment is reflected in the output of the reaction torque observer.

Keynote paper — Real world haptics applied to forceps in robot surgery

This paper presents the technological achievements in realizing the force feedback in surgical robots. No force sensor is used in sensing the force. Disturbance observer and its variant, reaction torque observer is used to detect the force. Bilateral control is used to transmit vivid sensations from the forceps end to the surgeon.