LOPES (exoskeleton)

The goal of the LOPES project (LOwer-extremity Powered ExoSkeleton) is to design and implement
a gait rehabilitation robot for treadmill training. The target group consists of people who have
suffered a stroke and have impaired motor control.
The main goals of LOPES are:
The mechanical construction should offer assistance in leg movements in the forward direction
and in keeping lateral balance. Within the LOPES project, it has been decided to realize this
by connecting the limbs of the patient to an exoskeleton so that robot and patient move in parallel.
Most gait rehabilitation robots that are currently being developed [1, 2] focus on the support of the
entire gait cycle as a single unit. These robots use joint trajectories of the entire gait cycle and
offer a uniform (more or less) stiff control along this trajectory. This means that the patient
receives support in gait phases where support is necessary but also in phases where support isn’t
necessary. Studies have been done on an exoskeleton [3] that propose adaptive control methods which
minimize the interaction forces with the patient with respect to an adaptable reference pattern,
but these still control the entire gait cycle. Studies have also shown that walking with the 
Lokomat requires significantly less energy than normal walking [4]. LOPES aims to support
and not take over those tasks that the patient is unable to perform without help using an impedance
control scheme. This will lead to a more active participation from the patient’s side. The tradeoff
for more active walking will likely be a smaller overall distance during therapy sessions. The
implication of selective function support is that the robot will have two extreme modes in which it
should be able to function, these are:
Currently the first prototype has been completed. This prototype has 8 actuated DOF (series elastic actuation) following the design as in [5]. Clinical evaluations will be done in the course of 2007.