Abstract
The aim of this project is to develop a novel and remotely accessible Hardware-in-the-loop
Simulator (HILS) System as a multipurpose, multilevel laboratory test-bed for
undergraduate and graduate education in robotics, mechatronics and control.
The proposed HIL architecture will be used for the real-time simulation of the
PUMA 560 robot manipulator at the UAF Electrical and Computer Engineering Department
where both structures will be made accessible simultaneously for on-site and
remote experiments via the Internet. The state-of-the-art motion control and
information technologies proposed in the project will provide a low-cost and
highly efficient solution for the wide range of experimentation needs of both
on-site and remote students in the above mentioned engineering courses.
Project Description
The HIL concept proposed in this project is different from the previous robotics
related HILS, in that besides its capability for remote access, it involves
a major part of the actual hardware creating the motion, in the physical robot
system hence providing a more realistic educational and research tool in robotics,
mechatronics and control related courses in comparison to merely computer based
simulations. The goal of the project requires the problem to be addressed in
two parts:
- Development of dynamic modeling and control software
for the robot in consideration:
The proposed HIL architecture involves two motors
coupled to one another by their shaft to perform the joint-by-joint simulation
of any given robot configuration. In this architecture, which can simulate 1
degree-of-freedom (DOF) at a time, one of the motors is used as the joint actuator,
while the other motor coupled to it, is used as the dynamic load simulator to
generate in real-time the internal and external dynamics affecting the joint
actuator for that particular DOF in a given configuration. The choice of the
joint actuator is made based on the motor used in the actual robot; while a
direct-drive motor (DDM) is used as the dynamic load simulator, considering
the high speed, high accuracy demands of real-time simulation. Both motors are
run by a high performance controller board, which will be used to develop the
designed control methods for the joint motor, while also generating the external
and internal dynamics affecting that joint. Thus, by performing the joint-by-joint
simulation for each DOF, the joint trajectories will be combined to obtain the
trajectory and performance of the end-effector under the designed control methods
and disturbances taken into consideration. The motion trajectories can also
be combined to perform the computer animation of the actual robot.
Although the proposed HIL could be used to simulate
any robotic configuration, in this project, we aim to design a HIL simulator
for the open-architecture PUMA 560 robot at the UAF ECE Department. The two
systems will be used simultaneously for control and robotics related courses
and will be accessible for both on-site and remote users. The HIL simulator
for PUMA 560 comprises of a permanent DC motor - which is the joint actuator
in PUMA 560, a DDM used as the load simulator and DS1104 MATLAB/Simulink compatible
high performance controller to run the control algorithms and dynamics simulation.
- Development of Software for Remote Accessibility
is involved with the development of software to facilitate the client/server
communication and multilevel access to control tools provided to the remote
user.
As a Web server, we plan to use Apache Web Server
with Tomcat. Tomcat is a free open-source implementation of Java Server and
Java Server Pages (JSP) technologies or any other commercial web server, which
will allow a better security and access control.
For the database server, we will use MySQL ; the database will contain the list
of users that have permission to control our systems. In addition to that, it
might contain sets of predefined operations to be used for training or teaching,
or to demonstrate the performance of various control algorithms developed by
our team. Java Classes will communicate with mySQL Database using a free JDBC
driver. MySQL Connector/J converts Java Database Connectivity calls into the
network protocol used by the MySQL database. It simplifies the process of interaction
of Java programs with a database, even in a heterogeneous environment. MySQL
Connector/J is a Type IV JDBC driver and has a complete JDBC feature set that
supports the capabilities of MySQL.
Users access the remote robotic lab using any device
capable of running a web browser, such as desktop computers, notebooks, and
personal digital assistants. A simple graphical interface will allow users to
perform experiments in three different ways. The results of simulation will
be presented to the user through the graphical interface, and will include the
animation of movements of the simulated environment. In addition to that, a
user will be able to request an image of the robot and its environment, to confirm
the successfulness of the operation. A separate set of client-server programs
will be written to facilitate image capturing from the camera and transfer of
images to the user's web browser.
The first and simplest way to control the hardware
using our system would be to select simulation parameters for the set of pre-defined
commands that control the movements of the robot. After analyzing the results
of the operation, user can decide to repeat the experiment with another set
of parameters and/or commands.
However, the main contribution of this software
system is that users not only will be able to test the system performance for
certain trajectories by changing the allowed parameters in a variety of control
algorithms provided in advance, but will also have the capability to perform
a full open-architecture control on the experimental setup, by using his/her
own algorithms.. To facilitate that, users will be given the capability to submit
their own C programs that perform actuator control. To make it easier for a
user to use our platform, the graphical interface will make use of pre-defined
blocks that implement hardware-dependent operations, such as I/O operations,
access to analog/digital converters, etc. By selecting appropriate blocks and
by establishing connections between them, users will quickly build a hardware
interface for their control applications. Our software system will make sure
that a proper hardware interface for our particular board is built and integrated
with the control program submitted by the user.
Finally, users who have access to MATLAB and Simulink
environments on their computers, as well as the same control board used in
our systems will be given the opportunity to submit a Simulink program that
can be directly compiled and downloaded to our board, once it passes safety
checking.
We plan to keep the basic user interface simple,
so that it can be accessed quickly even over slower modem connections. At the
same time, the simple graphical interface will allow users to control our systems
even from devices with limited graphical capabilities, such as personal digital
assistants and mobile phones.
Impact
The proposed HIL simulator for PUMA 560 will be
used in combination with the PUMA 560 robot manipulator in the undergraduate
course "Fundamentals of Automatic Control" and graduate courses "Robot Modeling and Control and Modern Control Engineering"
taught by the PI. The open architecture PUMA 560 is an excellent tool of education
and research for students who already have some practical experience with robots;
however, due to its open architecture features, it should always be used after
appropriate simulations are performed. The proposed HIL setup will provide a
more realistic simulation platform in comparison to computer simulations and
moreover, will add to the quality of teaching and learning in highly theoretical
areas such as system modeling, analysis, and design of control methods involved
in all robotics and control courses. It will also provide a practical understanding
of the need for simulation, as well as a means for interpretation of discrepancies
between simulation and actual results.
Those classes have so far been taught on a theoretical
basis with no labs, but with computer support provided with MATLAB/Simulink
simulations; therefore, the addition of the HIL setup to the courses will
definitely add versatility and increase quality and motivation.
The remotely controllable HIL robot simulator ultimately
will serve as an efficient research/education tool, saving the user money and
time.
Innovation
The proposed HIL simulator architecture for on-site
and remote robotics/mechatronics/control education is the major innovation offered
by this project. The proposed HIL structure provides the users the capability
to experiment with any robotic configuration they desire, without the need for
the actual physical presence of the equipment. An important contribution is
the open architecture characteristic of the HIL simulator enabling the user
to develop his/her own control algorithms on the system, once again without
the need for costly open-architecture robot systems. internet-based remote control
of the system. Finally, the approaches taken to provide internet based full
remote controllability for the system are also the contributions of the proposed
project.
Feasibility
The equipment of the project is provided by an NSF-CISE
grant as well as the TAB Committee of UAF. The Northwestern Academic Computing
Consortium (NWACC) will provide summer salaries for the graduate students.
Technology Transfer and Outreach
The sharing of information and resources is the
major goal of the project. The remote capability outcomes of the project will
also be used in our future projects to reach remote K-12 students and native
communities.
