SphinxPC

Our computer aided linkage design software SphinxPC is in use in many research laboratories exploring the applications of a special class of spatial mechanisms, known as spherical linkages. The goal of a linkage design project in SphinxPC is a 4R linkage that guides a body either through four planar positions or through four spatial orientations. Here is the most recent paper describing SphinxPC:

• D. Alan Ruth, and J. Michael McCarthy: The Design of Spherical 4R Linkages for Four Specified Orientations.
• Here is the SphinxPC Manual.

Design of Spatial Mechanisms

We are developing new theoretical and software methodologies for the design of general spatial mechanisms that perform robotic tasks. Virtual Reality is being examined as a means to address the severe visualization challenge posed by these systems. Some recent papers in this area are:

• J. Michael McCarthy, "The Synthesis of Planar RR and Spatial CC Chains and the Equation of a Triangle," Special Combined Issue of theASME J. of Mechanical Design and J. of Vibration and Acoustics, 117(B):101-106, June 1995.
• Andrew P. Murray and J. Michael McCarthy, "Determining Burmester Points from the Analysis of a Planar Platform," ASME J. of Mechanical Design, 117(2A):303-307, June 1995.
• Pierre Larochelle and J. M. McCarthy, "Designing Planar Mechanisms using a Bi-invariant Quaternion Metric,"ASME Journal of Mechanical Design. 117(4):646-651, December 1995.
• Andrew P. Murray and J. M. McCarthy, "Passing a Central-axis Congruence through Six Arbitrary Lines in Space," ASME J. of Mechanical Design. 118(4):515- 519, December 1996.
• Andrew P. Murray and J. M. McCarthy, "Center-point Curves through Six Arbitrary Points," ASME Journal of Mechanical Design 119(1):36-39, March 1997.
• Karl R. Etzel and J. M. McCarthy, "Interpolation of Spatial Displacements using the Clifford Algebra of E4," ASME Journal of Mechanical Design, 121(1):39-44, 1999.

Recent Papers:

• Andrew P. Murray and J. M. McCarthy, "Burmester Lines for Five Position Synthesis from the Analysis of a 3-CPC Platform," ASME Journal of Mechanical Design, 121(1):45-49, 1999.
• J. M. McCarthy and S. G. Ahlers, "Dimensional Synthesis of Robots using a Double Quaternion Formulation of the Workspace," Proc. 9th Int. Symp. Robotics Research, Snowbird, UT, Oct. 9-12, 1999, pg. 1-6.
• Shawn G. Ahlers and J. Michael McCarthy, "The Clifford Algebra of Double Quaternions and the Optimization of TS Robot Design," Applications of Clifford Algebras in Computer Science and Engineering, (E. Bayro and G. Sobczyk, editors), Klewer, 2000.
• J.M. McCarthy and R.Mohan C. Bodduluri, "Avoiding singular configurations in finite position synthesis of spherical 4R linkages," Mechanism and Machine Theory, 35:451-462, 2000.
• A. Perez and J. M. McCarthy, "Dimensional Synthesis of Spatial RR Robots," Advances in Robot Kinematics, J. Lenarcic, ed.
• J. Michael McCarthy, "Mechanisms Synthesis Theory and the Design of Robots," Proc. Int. Conf. Robotics and Automation, San Francisco, CA, April 24-28, 2000.

Novel Assistive Devices for the Severely Disabled

Powered assistive devices have been shown to provide improvements in psychosocial and developmental skills of severely disabled children, as well as increases in their general activity level. Advances in the design of spatial linkages is yielding new devices with unique capabilities for deploying and stowing accessories for the wheel-chair bound. The result is the efficient design and construction of devices that provide singly-actuated spatial movement for the disabled, expanding the opportunity for independent activity fundamental to cognitive development.

Here are photos of a wheelchair with prototype devices installed.