This paper describes an experimental test-bed that was developed to assist
and assess rehabilitation during physical and occupational therapy. A PUMA
260 robot was used with a controller and interface software developed in-ho
use. The robot is designed to operate in two modes: (1) passive and (2) act
ive. In the passive mode, the robot moves the subject's arm through specifi
ed paths. In the active mode, a subject guides the robot along a predefined
path overcoming specified joint stiffness. In this mode, the controller co
mpensates for gravity so that the robot can support its own weight in an ar
bitrary configuration, The developed graphical interface enables display of
the current configuration of the robot in real-time, and allows us to cust
omize experiments for a subject, and collect force and position data during
an experiment. The results of a preliminary study with healthy subjects us
ing this test-bed are also presented along with issues involved in the choi
ce of paths and interpretation of the results.