Biomedical Engineering Reference
In-Depth Information
Tab l e 2 . 3
Degrees of Freedom of RUPERT and their Direction of
Actuation.
Degree-Of-
Direction of
Actuation in the
Freedom
Actuation
other direction
Shoulder Flexion/
Shoulder Flexion
Gravitational pull
Extension
on the arm
Elbow Flexion/
Elbow Extension
Subject's motor
Extension
control
Elbow Supination/
Elbow Supination
Subject's motor
Pronation
control
Wrist Flexion/
Wrist Extension
Subject's motor
Extension
control
Humeral Internal/
Humeral External
Subject's motor
External Rotation
∗
Rotaiton
control
∗
Additional DOF present in RUPERT IV.
•
Low Cost
- These actuators can be easily built using parts that can be
obtained off-the-shelf, which lowering the cost of the acuator.
These features of the PMA fit very well with the primary goal which is to develop
a simple, light-weight and low cost rehabiliation robot.
All versions of RUPERT are instrumented with two types of sensors - (a) joint
angle sensors to sense the angular position of each DOF, and (b) pressure sensors
to monitor the pressure inside the PMA actuating each DOF. The joint angle data
provides the joint space kinematics of the movement performed with RUPERT,
which can be used for deriving other kinematic variables. The pressure sensor
data, on the other hand, can be used for obtaining some very basic and crude
information about some variables related to movement kinetics. RUPERT IV uses
non-contact magnetic angle sensors (Ametes 360 ASMC-01, GWM Assosciates)
and peizoelectic pressure sensors (MPX5700GP, Freescale) for sensing the angular
position of the joints and the pressure in the PMAs respectively.
RUEPRT has two unique features that distinguish it from the other therapy
robots currently available for the upper-extremity. The first and most important
feature of RUPERT is that it is a wearable exoskeleton robot that allows a greater
degree of mobility to the patient. There are a few exoskeleton rehabilitation robots
used in various research labs (Nef and Riener (2008), Sanchez
et al.
(2005), Carignan
et al.
(2005)). All these robots, however, are grounded i.e. they are fixed to a
static structure. The wearablity of RUPERT, on the other hand, allows it to be used
for training tasks in different settings, sitting or standing etc., which is important
from a task-oriented training perspective. For example, a simple reaching task
might involve the same set of UE muscles both in a standing or a seated position;
while, the postural control muscles will be drastically different in these two cases.
Thus the availability of a wearable robot makes it possible to practice tasks in all
