Cooperative Robotic Manipulators

Robots doing a cooperative insertion of a flexible object

Totally Cooperating Manipulator Summary

To date, the use of robots within the manufacturing environment has been limited to non-contact type applications such as spray-painting, welding and inspection. To extend their use, robots need to be able to identify, acquire and manipulate objects with care and precision. To achieve precise object manipulation, two-arm cooperation and force sensing are essential. Equally important is the development of control techniques that are robust to practical-system issues such as motor cogging, joint flexibility, etc.

To study the problem of cooperative manipulation, the ARL has developed a state-of-the-art facility.

Critical Technologies

• Hierarchical control of cooperative manipulators.
• Object-based task-level control.
• Robot control in the present of joint flexibility.
• Non-linear feedback.

Experimental Platforms

• Two two-degree-of-freedom SCARA-type manipulators with endpoint force sensors and a vision system.
• Two four-degree-of-freedom SCARA-type manipulators with end-point position sensors, end-point force sensors, joint encoders, torque sensors, and a vision system. These robots exhibit exaggerated joint flexibility.

Experimental Demonstrations to Date

• Dynamic control of end-effectors and objects using direct visual feedback in real-time by Stan Schneider~\cite{Schneider:89}.
• Cooperative manipulation of delicate objects: Fluorescent Lamp Assembly by Larry Pfeffer~\cite{Pfeffer:93,PfefferC:93}.
• Robotic composite-tape layout by Rick Hosey~\cite{DARPAfinal:91}.
• Object acquisition and insertion by Stan Schneider~\cite{Schneider:89,SchneiderC:93}.
• Capture and cooperative manipulation from a moving base by Rob Vasquez~\cite{Vasquez:92}.
• Capture and cooperative manipulation of an object with internal dynamics by Dave Meer~\cite{Meer:94}.