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Robotics Research
K. Abdel-Malek, Department of Mechanical Engineering
H.J. Yeh, Microtek International, Inc., Taiwan
A. Hager, Qualicoat, Inc., NY
L. Adhami, Ecole Superieure en Sciences Informatiques, Sophia-Antipolis, France
J. Yang, PhD program at the University of Iowa

Research in the following areas:
1. Off-Line Simulation and Programming
2. Kinematics and Workspace analysis
3. Design of Robot Manipulators
4. Dexterity and Placement of robot manipulators
See our Publications List by Topic

1. Off-Line Simulation and Programming (Based on US Patent 5,511,147)
In a manufacturing environment consisti ng of a multiple of cells, cell-setup time is often the most costly aspect. Robotic manipulator arms have been used in the past increase productivity. Although in many cases, manipulators have reduced setup times, they do require sophisticated program m ing. Particularly when the tasks cannot be taught using a teaching device (e.g. teach pendant). The Objective of the three-dimensional computer-aided robotics interface (called 3D-CAI) is to provide the robot programmer with a simple tool to program complex ro b otic functions through interactive CAD techniques. Representations of the external environment is constructed using solid modeling techniques. Manipulation of solids using boolean operators is performed to represent complex objects. The configuration ( p osition and orientation) of a triad can be modified by the user. 3D-CAI provides an off-line programming method where logic, repetitive tasks, and sensory control can be programmed interactively. Trajectories are planned by manipulating three-dimensiona l curves on the screen. Icons are used to represent end-effector configurations of the manipulator. Linking icons via three-dimensional curves mandates the motion of the manipulator arm. The introduction of a graphical environment reduces the task of vi s ualizing points, orientations, and trajectories rendering the environment simple to use for non-robotics experts. Two implementations of this environment are discussed: an implementation into a sheet-metal manufacturing cell to reduce setup times, and an implementation into a workstation for aiding disabled individuals to feed themselfs through a voice recognition system. Difficulties encountered in those implementations are discussed. This work is based on US patent (Abdel-Malek 1995). Subsequent work included methods for checking and avoiding collisions.

• US Patent Number 5,511,147, US Patent and Trademark Office (1996), Washington, D.C.
• Abdel-Malek, K., (1996), "Graphical Interface for Robot", Robotics and Computer-Integrated
  Manufacturing, Vol. 12,(3), p. 288.
• Abdel-Malek, K. and Yeh, H.J., (1997), "Path Trajectory Verification for Robot Manipulators in a
  Manufacturing Environment" IMechE Journal of Engineering Manufacture, Vol. 211, part B, pp. 547-556.
• Abdel-Malek, K., (1999), "Collision Detection of Manipulator Arms with Complex Links," International Journal of Robotics and Automation, Vol. 14, No.2, pp. 78-86.

• Liu, J.F. and Abdel-Malek, K., (in press), "Robust Control of Planar Dual-Arm Cooperative Manipulators", Robotics and Computer-Integrated Manufacturing
  
  
  2. Kinematics and Workspace Analyses
  Rigorous mathematical formulations for modeling and analyzing serial robot manipulators have been created. Using these formulations, we are able to obtain closed form solutions of the workspace including barriers inside the workspace where the manipulator exhibits control difficulties. Because of this novel approach, we are able to address issues that were only addressed using numerical techniques. We have also been able to demonstrate the workspace envelope (and voids) for many manipulators. For example, the figures below show the workspace and internal surfaces (also called in the literature as singular surfaces).

• SEE ALSO A RELATED SITE: THE SWEPT VOLUME COMMUNITY

Figure 1 A 4R manipulator Fig. 2 The workspace depicting all singular surfaces

Extension of this work has been implemented to

Human Workspace Analysis

• Abdel-Malek, K., Yeh, H-J, and Khairallah, N., (1999), "Workspace, Void, and Volume Determination of the General 5DOF Manipulator, Mechanics of Structures and Machines, 27(1), 91-117.
• Liu, J.F., and Abdel-Malek, K., (1999), "On the Problem of Scheduling Parallel Computations of Multibody Dynamic Analysis", ASME Journal of Dynamic Systems, Measurement and Control, Vol. 121, No. 3, pp. 370-376.
  
  
  3. Design of Robot Manipulators
  Design aspects of a six degree-of-freedom high accuracy manipulator are presented. The manipulator arm (called the UTI-arm) comprises four rev olute and two prismatic joints. The mechanical design of the manipulator is aimed at obtaining high accuracy and a high stiffness to weight ratio of the links. Prestressing of mechanical elements is performed to transform strength to stiffness. Design o f links under tension load is carried out to enhance bending stiffness. In the past, researchers have reported inefficiency of prismatic joints due to their high compliance. Compared to a uniform thin walled tube, prismatic joints used in this design pr o vide an isotropic, higher bending stiffness, with a relatively low loss in torsional stiffness. Experiments were conducted to verify the theory presented for calculating torsional stiffness of such joints. A finite element model was also used to validat e the model. The mechanical design of the arm is presented in detail in view of the proposed prismatic joint cross section and the prestressing effects. }{\i }}
  
  
  Manipulator and Wrist
  
• Abdel-Malek, K. and Paul, B., (1998), "Criteria for the Design of Manipulator Arms for a High Stiffness to Weight Ratio," SME Journal of Manufacturing Systems, Vol. 17, No. 3, pp. 209-220.
  
  

4. Dexterity and Placement of Robotics Manipulators
Criteria and implementation for the placement robot manipulat ors with the objective to reach specified target points are herein addressed. Placement of a serial manipulator in a working environment is characterized by defining the position and orientation of the manipulator\rquote s base with respect to a fixed reference f rame. The problem has become of importance in both the medical and manufacturing fields, where a robot arm must be appropriately placed with respect to targets that cannot be moved. A broadly applicable numerical formulation is presented. While other met h ods have used inverse kinematics solutions in their formulation for defining a locality for the manipulator base, this type of solution is difficult to implement because of the inherent complexities in determining al inverse kinematic solutions. The appro a ch taken in this work is based on characterizing the placement forcing a cost function to impel the workspace envelope in terms of surface patches towards the target points and subject to functionality constraints, but that does not require the computatio n of inverse kinematics. The formulation and experimental code are demonstrated using a number of examples.

• Abdel-Malek, K. and Yeh, H. J., (2000) "Local Dexterity Analysis for Open Kinematic Chains," Mechanism and Machine Theory, Vol. 35, pp. 131-154.

• Abdel-Malek, K., (1996), "Criteria for the Locality of a Manipulator Arm with Respect to an Operating Point,"IMEChE Journal of Engineering Manufacture, Vol. 210 (1), pp. 385-394.