This paper describes the development of an autonomous serpentine robot. This robot is a 12 degree of freedom, untethered, hyper-redundant planar robot, named Kaa. Experiments were conducted in its application to mobility tasks that would be useful in locomotion among parallel pipe structures similar to those found in industrial plants. Kaa utilizes a behavior control system. Unlike classical approaches, that decompose the control system functionally, behavior control approaches decompose the control system by task. This control scheme requires very little computation; Kaa uses two 8-bit, 1 MIP microprocessors with a total of 36 Kbytes of memory. Only simple tactile sensing is employed; the distances between objects in the environment and the robot are neither implicitly modeled nor explicitly sensed by the robot. The behavior control system developed allowed this robot to reliably perform complex autonomous mobility and manipulation tasks with limited computation and sensing resources.

This paper describes a series of robots developed at JPL to demonstrate the feasibility of using a behavior-control approach to control small robots on planetary surfaces. The round-trip light-time delay makes direct teleoperation of a mobile robot on a planetary surface impossible. Planetary rovers must therefore possess a certain degree of autonomy. However, small robots can only support small computers (due mostly to power, not size constraints). Behavior control provides a means of autonomous control that requires very little computation. The robots described in this paper all used 8-bit, 1-MIP microprocessors with as little as 4 k and no more than 40 k of memory, and extremely simple sensors. Despite these limitations they reliably perform both autonomous navigation and manipulation in both indoor and outdoor rough-terrain environments.>

The authors' long-term goal is to discover reasonable constraints under which an automatic uncertainty-handling strategy (for robot part-mating tasks) is guaranteed to succeed. As the first step they introduce a concept of contact formations to describe contacts among parts in a system, aiming at reducing the dimensionality of assembly verification. They also describe a technique for identifying contact formations in spite of errors in sensing and geometric uncertainties. It is impossible to verify termination conditions in general. The notion of design constraints is introduced, and design constraints for which verification can be guaranteed are formulated. The constraints are reasonable in the sense that they do not impose unrealistic conditions on typical designs. Results of implementation on a robot system consisting of PUMA robot with RTI force/torque sensors support the theoretical derivations and show empirically that the theoretical constraints can be relaxed somewhat and good results still be obtained.>

Grip determination is essential to any task-level planning process. The complete force/moment equations are presented for grasping employing a rigid two-fingered gripper with a thin elastic layer on the contacting surface. The surface contact is modeled as a linear pressure variation. The quality measure of a grip is taken to be the coefficient of friction needed to keep the held object from slipping between the fingers under applied forces and moments. The lower the coefficient of friction, the better the grip. Incorporation of this evaluation into general grip selection strategy is discussed, and several examples are given.

Grip determination is essential to any task level planning process and to situations in which the pose of the part to be grasped is not known a priori. This paper presents the complete force/moment equations for grasping via a rigid two-fingered gripper. Surface contact is modeled as a linear pressure variation. The quality measure of a grip is taken to be the coefficient of friction needed to keep it from slipping under applied forces and moments, the lower the coefficient of friction, the better the grip. The incorporation of this evaluation into a general grip selection strategy is discussed and several examples given.