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Biologically Inspired Robotics
a hybrid sensor that can measure both optical and bioelectrical signals
of the same spot simultaneously and evaluate it. The developed sensor
consists of holography laser modules and electrodes. The holography
laser modules contain an emitter and receiver. In order to evaluate the
hybrid sensor, three kinds of experiments were carried out: (1) operation
verification of the hybrid sensor probe in which the pulse waves and the
alpha wave were measured with the hybrid sensor probe; (2) an optical
data collection experiment in which the optical output was found to be
high when the participant was in relaxation state; on the other hand,
while the participant was executing mental tasks such as algebraic calculations the optical output lowered; and (3) an assistive device control
experiment in which the participant tried to move the upper limb assistive device 10 times. The upper limb movement was recorded 24 times
during this period. However, 7 times (out of 24) upper limb movement
corresponded to the participant’s intention was recorded 5 s before or
after the switch was pressed. We developed and evaluated a hybrid sensor that can collect both kinds of optical and bioelectrical signals from
the same spot on the scalp in order to measure brain activity by using
optical and bioelectrical data.
10.1 Introduction
It is difficult for patients suffering from advanced stages of amyotrophic
lateral sclerosis (ALS) and severe spinal cord injuries to transmit bioelectrical signals from the brain to peripheral nerves. They cannot use assistive
devices such as the robot suit HAL that are controlled using bioelectric signals (Hayashi et al. 2005; Kawamoto and Sankai 2005; Lee and Sankai 2003;
Nakai et al. 2001; Okamura, Tanaka, and Sankai 1999; Suzuki et al. 2007)
measured at the peripheral nerves. Residual functions such as voice or eye
movements can be used with assistive devices, but these methods place great
strain on patients. A brain–computer interface (BCI) that collects the patient’s
movement intentions and controls devices makes it easier for patients to use
assistive devices in this manner.
In order to realize a user-friendly BCI, it is necessary to measure brain
activity noninvasively. There are several methods for scanning brain activities. Functional magnetic resonance imaging (fMRI), positron emission
tomography (PET), and magnetoencephalography (MEG) are methods that
measure brain activity accurately. However, these methods require very
large and expensive equipment. Their readings also contain a delay, due to
the fact that they are based solely on blood flow. It is not possible to maintain
a comfortable lifestyle and use these devices for long periods of time.
On the other hand, there are methods using portable devices, such as
electroencephalograms (EEGs) and functional near-infrared spectroscopy
Biologically Inspired Robotics
a hybrid sensor that can measure both optical and bioelectrical signals
of the same spot simultaneously and evaluate it. The developed sensor
consists of holography laser modules and electrodes. The holography
laser modules contain an emitter and receiver. In order to evaluate the
hybrid sensor, three kinds of experiments were carried out: (1) operation
verification of the hybrid sensor probe in which the pulse waves and the
alpha wave were measured with the hybrid sensor probe; (2) an optical
data collection experiment in which the optical output was found to be
high when the participant was in relaxation state; on the other hand,
while the participant was executing mental tasks such as algebraic calculations the optical output lowered; and (3) an assistive device control
experiment in which the participant tried to move the upper limb assistive device 10 times. The upper limb movement was recorded 24 times
during this period. However, 7 times (out of 24) upper limb movement
corresponded to the participant’s intention was recorded 5 s before or
after the switch was pressed. We developed and evaluated a hybrid sensor that can collect both kinds of optical and bioelectrical signals from
the same spot on the scalp in order to measure brain activity by using
optical and bioelectrical data.
10.1 Introduction
It is difficult for patients suffering from advanced stages of amyotrophic
lateral sclerosis (ALS) and severe spinal cord injuries to transmit bioelectrical signals from the brain to peripheral nerves. They cannot use assistive
devices such as the robot suit HAL that are controlled using bioelectric signals (Hayashi et al. 2005; Kawamoto and Sankai 2005; Lee and Sankai 2003;
Nakai et al. 2001; Okamura, Tanaka, and Sankai 1999; Suzuki et al. 2007)
measured at the peripheral nerves. Residual functions such as voice or eye
movements can be used with assistive devices, but these methods place great
strain on patients. A brain–computer interface (BCI) that collects the patient’s
movement intentions and controls devices makes it easier for patients to use
assistive devices in this manner.
In order to realize a user-friendly BCI, it is necessary to measure brain
activity noninvasively. There are several methods for scanning brain activities. Functional magnetic resonance imaging (fMRI), positron emission
tomography (PET), and magnetoencephalography (MEG) are methods that
measure brain activity accurately. However, these methods require very
large and expensive equipment. Their readings also contain a delay, due to
the fact that they are based solely on blood flow. It is not possible to maintain
a comfortable lifestyle and use these devices for long periods of time.
On the other hand, there are methods using portable devices, such as
electroencephalograms (EEGs) and functional near-infrared spectroscopy