A number of control methodologies have been studied for assistive robotic technologies. Since the human motions in a daily life consist of multiple phases, such as walking, sitting and standing, controllers for assistive robots are required to be able to cope with different motion phases. For this reason, hybrid control which is able to occasionally switch control algorithms according to the motion phases has been preferred in the assistive robots, in particular wearable robots. In this paper, a generalized control framework is proposed as a fundamental framework for the hybrid assistive control and its stability is analyzed using the framework. The proposed control framework is implemented into a lower-limb exoskeleton robot and its effectiveness is verified thorough experiments.

Exoskeletons are attracting a great attention as a new means of rehabilitation devices. In such applications, control algorithms of exoskeletons are often inspired by nature for natural and effective assistance for patients. In this paper, a control algorithm is inspired by aquatic therapy. Aquatic therapy has various benefits for rehabilitation processes based on useful properties of water, e.g. buoyancy and drag. However, realization of such effects is challenged by limitations in hardware, such as mechanical impedance or impreciseness of actuator forces. Therefore, the resistive forces generated by actuators, which cause serious discomfort to patients, are precisely modeled and compensated to realize the control algorithm inspired by aquatic therapy effectively. The proposed methods are implemented in SUBAR developed by Sogang University and verified by experiments.

The Sogang University biomedical assistive robot (SUBAR), which is an advanced version of the exoskeleton for patients and the old by Songang (EXPOS) is a wearable robot developed to assist physically impaired people. It provides a person with assistive forces controlled by human intentions. If a standard geared DC motor is applied, however, the control efforts will be used mainly to overcome the resistive forces caused by the friction, the damping, and the inertia in actuators. In this paper, such undesired properties are rejected by applying a flexible transmission. With the proposed method, it is intended that an actuator exhibits zero impedance without friction while generating the desired torques precisely. Since the actuation system of SUBAR has a large model variation due to human-robot interaction, a control algorithm for the flexible transmission is designed based on a robust control method. In this paper, the mechanical design of SUBAR, including the flexible transmission and its associated control algorithm, are presented. They are also verified by experiments.

Recently the technology of capsule endoscopy has developed dramatically and many researchers are making efforts to combine surgical function into the capsule type endoscope. In this paper, the micro biopsy module which is a part of the capsule endoscope is proposed. The proposed module is less than 2 mm in thickness and has a diameter of 10 mm. It consists of a trigger with paraffin block, rotational tissue-cutting razor with a torsion spring and controller. This module makes it possible for the capsule endoscope to obtain a sample tissue inside the small intestine which can not be reached by a conventional biopsy device. Through dedicated experiments, tissue samples were successfully extracted using the proposed biopsy module and the cells in samples were extracted and tested by a microscope.

This paper presents a novel minimally invasive MEMS (micro-electromechanical system)-based micro-biopsy catheter for the diagnosis of gastrointestinal tissue samples. Conventional macro-scale biopsy tools such as biopsy forceps often cause a significant discomfort, infectious risk, and injury to the patients. In this study, a disposable micro-scale biopsy tool is proposed for the first time and MEMS technology is implemented for the fabrication process. Micro-biopsy catheter successfully extracts tissue samples from the small intestines of the anesthetized rabbit and pig. The proposed micro biopsy catheter is found to be useful in minimally invasive diagnosis.

The learning control is applied to hybrid force and position control of robot manipulators. When the geometry and position of a constraint surface is known, the hybrid force and position controller and the feedforward compensator can be designed in the constraint coordinates. When the operation is periodic, the learning hybrid force and position control enhance the control performance as the feedforward compensator is updated in each cycle by the force and position error in the preceding trials. This scheme is proved to be asymptotically stable. A two degree of freedom SCARA-type direct-drive robot manipulator is used to test the learning hybrid force and position control. The deburring tool mounted on the upper link of the robot could follow a flat, tilted flat, and curved 1/4 " aluminum plate with a desired contact force of 10 N (within the root-mean-square force error of 1.95 N) and with a desired tangential velocity. The experiments confirmed the effectiveness of the learning hybrid force and position controller.>

A hybrid force and position controller with a feedforward compensator is designed in the constraint coordinates. When the operation is periodic, the learning control is applied to enhance the performance of the hybrid force and position control as the feedforward compensator is updated in each cycle by the force and position error in the preceding trials. This scheme is proved to be stable. In the experiments, a two-degree-of-freedom SCARA-type direct-drive robot manipulator was used. The deburring tool mounted on the upper link of the robot could follow a flat, tilted flat, and curved 1/4 inch aluminum plate with a desired contact force of 10 N, and with desired tangential velocity. Considering the loss of contact observed at the initial trial, the performance of the system improved significantly.>