Motivation

1
Antonio Yordan-Nones University of Puerto Rico,
Mayagüez Mentors Prof. Edward A. Lee Xiaojun
liu
Heterogeneous Modeling Design of a Robot Arm
Control System for Ptolemy II
http//chess.eecs.berkeley.edu
Modeling Control Systems in Ptolemy II Modeling
embedded control systems for robotics in Ptolemy
is very flexible since there are a variety of
models of computation to choose from. For
example, an electro-mechanical system could be
represented under continuous dynamics, and a
digital communications system may be more
appropriately modeled under the discrete-event
domain. Systems that employ multiple modes of
operation with overlapping computational domains
are hybrid models. Lynx-5 Robot Arm To
apply modeling techniques in Ptolemy and
demonstrate embedded software control of a
robotic manipulator we chose the Lynx-5 Robot
Arm. The Lynx-5 is an articulated manipulator
(RRR) with 2 planar links in an elbow-like
configuration and 4 degrees-of-freedom - each of
the 4 joints are controlled by dedicated servo
motors.
Designing a Robot Arm Actor
Motivation Robots and embedded control systems
are traditionally programmed to perform automated
tasks, yet accomplishing dynamically changing
tasks will typically require the use of
specialized software systems. In order to design
these sophisticated control systems the use of
computational modeling and simulation techniques
is necessary to ensure that final implementations
of the system perform optimally. Since even the
simplest robotic control systems are
intrinsically a mixture of heterogeneous
sub-systems, each focusing on a particular task,
we need a means of modeling the different aspects
of the system accurately and intuitively. Ptole
myII An Overview The focus of study in the
Ptolemy project is on modeling, simulating, and
designing embedded systems that require
heterogeneous and hybrid modeling, component
concurrency, and real-time responsiveness.
Ptolemy extends component-based design principles
by accurately managing the time continuum and
maintaining concurrency among actors, features
that are especially useful when designing control
systems software.

• Input
• 3D Cartesian Coordinates
• Output
• Incremental Servo Positions
• Notify reaching outside of the
• robots workspace

• Design
• Calculate the inverse kinematics
• Convert the degrees of rotation to absolute
  servo positions
• Verify servo bounds to stay
• inside of the robots workspace
• Step through the sequence of
• movements / positions of
• the servo motors
• Output a stream of bytes to the
• external serial servo controller

CASE STUDY Lynx-5 meets X-10 Remote Control

• Features
• A novel embedded system
• concurrent components
• discrete-events (DE)
• X-10 wireless remote control
• sends commands through the
• X-10 network
• Specify the cardinal orientation
• to move the arm
• ( up - down - left - right )
• Implement communication
• between 2 different models
• 2 different computers by
• sending datagrams

August 7, 2003