IEEE Robotics & Automation Magazine - March 2023 - 74

threatened. Therefore, the control technique for ensuring the
safe movement of human-robot systems is a key factor in the
design of rehabilitation robots.
This study discusses the development of a rehabilitation robot
with passive and active direct switching training [rehabilitation
robot direct switching (RRDS)] [17]. Only the passive training
mode of the rehabilitee following robot movement was examined
in [17], and the mode transitioning to active training following the
development of the rehabilitee's leg strength was not taken into
account compared with other walking training robots. The main
features of RRDS are as follows:
1) The passive and active training modes of the robot can be
directly switched in line with the walking characteristics of
people with dysfunctional walking.
2) A stochastic configuration network (SCN) with a simple
structure is used to estimate the uncertainty, and the hidden
layer nodes are randomly configured to accurately
depict human-robot motion environments.
3) A novel passive and active direct switching control method
is proposed, and passive constraints and active decisionmaking
concerning movement velocity can be realized.
Several simulation comparative analyses and experimental
studies have been performed on RRDS.
STRUCTURE DESCRIPTION OF THE RRDS
The RRDS is a rehabilitation walking training robot designed
for rehabilitees with lower-extremity disorders. The robot stores
many paths as desired movement paths after the physiotherapist
creates various training paths based on the rehabilitee's capacity
for walking. To help the rehabilitee walk more easily and
address the shortage of physiotherapists for rehabilitation, the
robot typically needs to follow a predetermined path. The overall
structure consists of a touch panel, an armrest, ultrasonic
sensors, omnidirectional wheels, and a height-adjustable main
body bracket, as shown in Figure 1.
■ The touch panel, as shown in Figure 1(a), can be used to
select the training mode of the robot and stop the robot in
the case of an emergency. In the rehabilitation training
process, a rehabilitee can walk in multiple directions, such
as forward and backward, or turn according to the doctor's
training program. Moreover, training can be stopped
immediately when an emergency is encountered. The
RRDS can help in independent rehabilitation training
without the need for doctor on-site care.
■ An armrest, as shown in Figure 1(b), is used to support
the rehabilitee's body. In walking training, rehabilitees
should place their forearms on the armrest to reduce the
pressure on the lower limbs. Pressure sensors were
placed under the armrest to obtain the pressure information
of the forearm on the RRDS.
■ When the ultrasonic sensor, as shown in Figure 1(c), is running,
it sends ultrasonic information to the surroundings and
feeds back the motion environment to a certain extent. It is
also used to avoid obstacles in the case of collision risk.
■ As shown in Figure 1(d), the omniwheel is a prominent
structural feature of the RRDS design. There are four omniwheels,
each of which is independently driven by a dc
motor. Combined with the appropriate tracking control
(a)
(b)
(c)
(d)
(e)
FIGURE 1. RRDS structure and walking training. (a) Touch panel, (b) armrest, (c) ultrasonic sensor, (d) omniwheel, and (e) safety seat.
74 IEEE ROBOTICS & AUTOMATION MAGAZINE MARCH 2023

IEEE Robotics & Automation Magazine - March 2023

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