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J. Daniel Morrow

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4 papers

1 author row

ICRA Conference 1997 Conference Paper

Manipulation task primitives for composing robot skills

J. Daniel Morrow
Pradeep K. Khosla

A manipulation task primitive is classified by the relative motion between two (rigid) parts. Only twenty different relative motions are possible and these can be used to guide the identification and development of manipulation task primitives. The goal is to build a richer library of robot capabilities in the manipulation domain. By identifying manipulation task primitives and instantiating solutions to them with available sensors and robot hardware in the form of sensorimotor primitives, we provide a higher-level abstraction for composing solutions to complex manipulation tasks. A key benefit is the ability to re-use costly sensor-based control algorithms for executing these primitives. We discuss the implementation of a few manipulation task primitives using force damping control and active vision feedback. Finally, we decompose a common task into two different skills using the primitives described.

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IROS Conference 1995 Conference Paper

Fast stable contact transitions with a stiff manipulator using force and vision feedback

Bradley J. Nelson
J. Daniel Morrow
Pradeep K. Khosla

Ideal manipulator end-effector transitions from noncontact to contact states should be fast and stable with minimal impact forces and without bounce. These specifications, however are difficult to simultaneously achieve, especially for the most common manipulator force control configuration employing a wrist force sensor and a stiff manipulator position loop. In this paper the authors present a control strategy that uses high bandwidth vision feedback (30 Hz) in addition to force feedback (100 Hz) for contact transient control. A nonlinear control strategy is proposed that considers force and vision feedback simultaneously and then switches to pure force control when the camera-lens system becomes unable to accurately resolve the location of the end-effector relative to the surface to be contacted. Experimental results are presented which demonstrate that a stiff manipulator can quickly contact a stiff surface stably without bounce. Results also show that the magnitude of the impact force spike is directly related to the accuracy with which contact surfaces are visually observed.

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ICRA Conference 1995 Conference Paper

Sensorimotor Primitives for Robotic Assembly Skills

J. Daniel Morrow
Pradeep K. Khosla

Many researchers are interested in developing robust, skill-achieving robot programs. The authors propose the development of a sensorimotor primitive layer which bridges the gap between the robot/sensor system and a class of tasks by providing useful encapsulations of sensing and action. Skills can then be constructed from this library of sensor-driven primitives. This reflects a move away from the separation of sensing and action in robot programming of task strategies towards the integration of sensing and action in a domain-general way for broad classes of tasks. For the domain of rigid-body assembly, the authors exploit the motion constraints which define assembly to develop force sensor-driven primitives. The authors report on the experimental results of a D-connector insertion skill implemented using several force-driven primitives.

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IROS Conference 1995 Conference Paper

Vision and force driven sensorimotor primitives for robotic assembly skills

J. Daniel Morrow
Bradley J. Nelson
Pradeep K. Khosla

Integrating sensors into robot systems is an important step towards increasing the flexibility of robotic manufacturing systems. Current sensor integration is largely task-specific which hinders flexibility. The authors are developing a sensorimotor command layer that encapsulates useful combinations of sensing and action which can be applied to many tasks within a domain. The sensorimotor commands provide a higher-level in which to terminate task strategy plans, which eases the development of sensor-driven robot programs. This paper reports on the development of both force and vision driven commands which are successfully applied to two different connector insertion experiments.

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