This paper presents a novel methodology to control walking speed of an exoskeleton for gait rehabilitation of stroke patients using feasibility-guaranteed trajectories. The controller uses interaction forces to estimate the desired walking speed. Instead of allowing each joint to move around a nominal trajectory, which could lead to infeasible gait patterns, the control algorithm proposed in this paper chooses joint trajectories for desired walking speed, which generates feasible gait patterns. With the interaction forces measured during walking, the walking speed intended by the patient is estimated. Then, based on the estimated walking speed, a reference trajectory stored in a database, which is checked if kinematic constraints required for walking are met, is chosen. Since checking feasibility is performed off-line before the training sessions, it is possible to ensure stability of walking without causing any computational time on-line.

This paper presents a novel motion control method of a micro-robot for biomedical applications. The proposed micro-robot is composed of a permanent magnet with oblique magnetization, and the electromagnetic actuation (EMA) system consists of only two pairs of Helmholtz coils arranged at a right angle on a horizontal plane. While conventional systems generally use the magnetic field gradient for the propulsion, the proposed system uses only a uniform magnetic field. By virtue of these strategies, we can make the system smaller and reduce the power consumption compared to the pre-existing EMA systems. To verify the feasibility of the proposed system, basic experiments and trajectory tracking were performed under different environments.

This paper introduces a novel exoskeleton system for gait rehabilitation, which allows natural pelvic movements. The developed lower extremity exoskeleton system, COWALK, has 14 degrees of freedom including four degrees of freedom for pelvic motion. From 113 healthy human subjects, 3D motion capture data were collected to determine mechanical design parameters and to generate gait patterns for the COWALK system. In order to reduce the affect of the weight of the robot, a gravity compensator was installed to support the weight of the robot. The performance of the COWALK system was validated by experiments. The experimental results from joint trajectories and pelvis movements show that the developed exoskeleton system can produce natural gait movements by augmenting the degrees of freedom for pelvic motion.

Training for balancing, which is governed by the motion of pelvis and thorax, is a key for gait rehabilitation. COWALK, which is a gait rehabilitation robot under development in our institute, is capable of pelvic motion training. In this paper, we describe a statistical method to generate pelvic motion which is considered to fit each person, i.e., personalized pelvic motion. We measured 14 anthropometric features of human and captured gait motion using an optical motion capture system from 113 healthy subjects. We setup a database of gait motion and body measurements; we define a 4 dimensional compact vector representation of pelvic motion, and body meta-feature, which is a weighted linear combination of the anthropometric measurements, to maximize statistical correlation between the former and the latter. To synthesize a personalized pelvic motion for a new subject, we search for k nearest neighbors in the space of body meta-feature (k-NN algorithm), and average the pelvic motions of them. We validate the algorithm using the database of 113 subjects by excluding each person, synthesizing a personalized pelvic motion for the subject, and comparing it with actual motion of the subject.

Lip synchronization is one of the most important technologies in the field of intelligent robotics. The natural and precise lip synchronization of robots could contribute to the improvement of human robot interaction and communication. In this paper, we designed a lip synchronization system for intelligent face robots using a text-to-speech system and robot mouth module. By applying several suggested lip synchronization control methods to this robot, we developed a reliable and high-performance robot lip synchronization system. Then, the overall performance of this system was verified through the experiments.

In this paper a safe arm with passive compliant joints and visco-elastic covering for human-friendly service robots is presented. The passive compliant joint (PCJ) is composed of a magneto-rheological (MR) damper and a rotary spring. The rotary spring gives the arm compliant property, but also it might be a source of vibration. Therefore the damper is introduced for damping effect and works as a rotary viscous damper by controlling the electric current according to the angular velocity of spring displacement. In an unexpected collision, the joints and cover passively operate and attenuate the applied collision force. The force attenuation property is being verified through collision experiments showing that the proposed passive arm overcomes limitations of an active compliant control approach.