Biomedical Engineering Reference
In-Depth Information
2.5 ROBOT CONTROLLER AND THERAPY MODES
In addition to the mechanical hardware of the robot, the RUPERT system consists
of other components that are required for using the robot to administer robot-
assisted therapy. The schematic diagram of the overall RUPERT system is shown
controller software that senses the state of the robot (joint and pressure signals) and
modulates its output to the electronic pressure reagulators (E22 series, Numatics,
Inc.), which in turn control the air pressure inside
the PMAs actuating the robot. The maximum input pressue to these pressure
regulators is set to 80 psi. The box housing the single board computer and the pres-
sure regulators (control box) is connected to a host PC through an Ethernet cable.
The communication between these two computers is achevied through the TCP/IP
and UDP protocols. The host PC houses a GUI that the therapist/physician uses
to set up the robot and the biofeedback interface for administering therapy.
2.5.1 RUPERT Controller Overview
The RUPERT controller was developed and tested in a Matlab/Simulink environ-
ment using the xPC toolbox. The overall structure of the controller for RUPERT,
Outer-Loop (OL), each with its own controller. The IL controller works at the level
of the individual joints. It consists of five independent PID-based joint position
controllers, corresponding to each DOF in RUPERT. These controllers are basically
PID controllers with some structural modifications, such as
(1) Saturation limit for the integrator.
(2) Saturation limit and a rate limit for the output from the controller. The
saturation limits on the output restricts the control output between
,where
0 corresponds to 0
psi
(relative to the atmospheric pressure) and 5 corresponds
to maximum pressure limit set for a given PMA.
[
0, 5
]
Figure 2.2
Schematic of the overall RUPERT system.
