Yuki Yokoo

Development of a novel FES control system based on treadmill motor current variation for gait rehabilitation of hemiplegic patients after stroke

In consideration of a large proportion of stroke survivors with persistent deficits, current interventions have limited ability to restore normal motor function. We propose a gait training system for gait rehabilitation of hemiplegic patients with convalescent stroke. It consists of a functional electrical stimulation (FES) device which is used to influence the gait pattern instantly to improve the quality of the gait, and a treadmill with two separated belts. The stimulus triggers from the FES could be controlled automatically by the subjects gait phase determination, including stance phase and swing phase. Gait phase could be estimated and recognized through observing current value variation of the treadmill motor during the subjects walking on the treadmill belts. In this paper, we have preliminarily tested the feasibility of the proposed method through hemiplegic simulation experiments. Also, Tibialis Anterior (TA) and quadriceps on the hemiplegic side were successfully stimulated by the expected FES stimuli during gait.

Intuitive operability evaluation of robotic surgery using brain activity measurement to identify hand-eye coordination

Surgical robots have undergone considerable improvement in recent years, but the intuitive operability, representing user inter-operability, has not been quantitatively evaluated. Thus, we propose a method for measuring brain activity to determine intuitive operability in order to design a robot with intuitive operability. The objective of this paper is to clarify the angle between the endoscope and the manipulator that facilitates users perceiving the manipulator as part of their body. In the experiments, while subjects controlled the hand controller to position the tip of the virtual slave manipulator on the target in the surgical simulator, we measured the brain activity through brain imaging devices. We carried out the experiment a number of times with the virtual slave manipulator configured in a variety of ways. The results show that activation of the brain is significant with the slave manipulator configured such that the angles are slanted with respect to the horizontal. We conclude that the body image affects hand-eye coordination, which is related to visual and somatic sense feedback.

Configuration of slave and endoscope in surgical robot based on brain activity measurement

Surgical robot has been considerable improvement in recent years, but their intuitive operability, representing user interoperability, has yet to be quantitatively evaluated. Thus, we propose a method for measuring brain activity to determine intuitive operability so as to design a robot with intuitive operability. The objective of this paper is to determine the angle and radius between the endoscope and the manipulator that allows users to perceive the manipulator as part of their body. In the experiments, subjects moved the hand controller to position the tip of the virtual slave manipulator on the target in the surgical simulator, measured the brain activity through brain imaging devices. The experiment was carried out a number of times with the virtual slave manipulator configured in a variety of ways. The results show that brain activation is significantly greater with a particular slave manipulator configuration. It concludes that the hand-eye coordination between the body image and the robot should be closely matched in the design of a robot with intuitive operability.

Intuitive operability evaluation of surgical robot using brain activity measurement to determine immersive reality

Surgical robots have improved considerably in recent years, but intuitive operability, which represents user inter-operability, has not been quantitatively evaluated. Therefore, for design of a robot with intuitive operability, we propose a method to measure brain activity to determine intuitive operability. The objective of this paper is to determine the master configuration against the monitor that allows users to perceive the manipulator as part of their own body. We assume that the master configuration produces an immersive reality experience for the user of putting his own arm into the monitor. In our experiments, as subjects controlled the hand controller to position the tip of the virtual slave manipulator on a target in a surgical simulator, we measured brain activity through brain-imaging devices. We performed our experiments for a variety of master manipulator configurations with the monitor position fixed. For all test subjects, we found that brain activity was stimulated significantly when the master manipulator was located behind the monitor. We conclude that this master configuration produces immersive reality through the body image, which is related to visual and somatic sense feedback.

Brain Activity Analysis for the Configurational Determination of Surgical Manipulation and Endoscope

This paper presents a novel method for evaluating a user’s feelings in a master–slave robotic surgical operation. By measuring brain activity, an engineer can quantify the user’s feelings during the operation from a cognitive science perspective. In contrast with conventional methods, the engineer can consider the user’s feelings in designing a robot with intuitive operability. The brain activity measurement method is well suited to not only surgical robots but also all master–slave robots. The objective of this paper is to determine the optimal distance between the slave and endoscope using brain activity measurement. We find that brain activity shows a significant peak when the user controls the virtual arm in a position matching the most natural hand-eye coordination.

Development of a novel gait rehabilitation system based on FES and treadmill-walk for convalescent hémiplégie stroke survivors

Recently, a large amount of stroke survivors are suffering from motor impairment. However, existed therapy interventions have limited effects to restore normal motor function. Thus, we proposed a novel control strategy for gait rehabilitation of hemiplegic patients. The whole system consists of a Functional Electrical Stimulation (FES) device and Treadmill-Walk system. FES contributes to improve the quality of the gait based on real-time adjustment of gait pattern. During gait, the electrical stimuli from separate output channels of an FES device are launched to stimulate two lower extremity muscles (Tibialis Anterior (TA) and Hamstrings). Stimulus launching procedure is based on identifying subjects gait state (stance and swing phases). According to the current variation of treadmill motor, gait phase and muscle activation of lower limbs can be determined during walking on Treadmill-Walk. Three able-bodied subjects simulated hemiplegic patients in the experiment. The results indicated that the proposed method is a safe, feasible and promising intervention.

Brain activity measurement based evaluation of active control of a treadmill

Many devices that offer lifestyle support, especially movement support, for the elderly have been recently developed. We have developed a new personal mobility device, Tread-Walk (TW), which is a walking support system for the elderly. Here we proposed a new control of a treadmill that enables users to walk with the same feeling as in normal level-ground walking. In this paper, we evaluated our proposed control method using a brain activity measurement, namely near-infrared spectroscopy. In particular, we quantitatively evaluated the operability, which has only been qualitatively evaluated previously. Results showed a notable tendency that brain activity depends on the accuracy of our proposed treadmill control. Then a possibility that a walking state could be evaluated from a brain activity was suggested. Our study validates the active velocity control of a treadmill according to brain activity measurement.