Showing papers by "William Whittaker published in 1992"

Position estimator for underground mine equipment

Abstract: A 2-D perception system that exploits the accuracy and resolution of a laser range sensor to determine the position and orientation of a mobile robot in a mine environment is described. The perception system detects features from range sensor data and matches the features to a map of the mine to compute the sensor position. The features used are line segments and corners, which represent the typical geometry of the mine walls and intersections found in room-and-pillar-type mining. The position estimate is refined by minimizing the error between the map and sensed features. This position information can be used for autonomous navigation when a map of the mine is available or to survey the mine in order to build such a map. The technique is applied to robot navigation in a mine mockup. A refinement of this system could guide machines to yield productive, safe mining operations. >

A walking prescription for statically-stable walkers based on walker/terrain interaction

Abstract: The walker/terrain interaction phenomena for the control of a statically stable walking machine are described. The algorithms, measures, and knowledge of walker/terrain interaction phenomena are then combined to form a prescription for how to walk on general terrain. This prescription consists of two parts: nominal control and reactive control. The function of nominal control is the evaluation and execution of planned motions, based on predicted foot force redistributions, to achieve reliable locomotion. The function of reactive control is the monitoring of walker/terrain interaction in real-time to detect anomalous conditions and then respond with the appropriate reflexive actions. Simulations and experiments have been used to test and verify various aspects of the walking prescription. >

Progress towards robotic exploration of extreme terrain

Abstract: A high degree of mobility, reliability, and efficiency are needed for autonomous exploration of extreme terrain. These requirements have guided the development of the Ambler, a six-legged robot designed for planetary exploration. To address issues of efficiency and mobility, the Ambler is configured with a stacked arrangement of orthogonal legs and exhibits a unique circulating gait, where trailing legs recover directly from rear to front. The Ambler is designed to stably traverse a 30 degree slope while crossing meter sized features. The same three principles have provided many constraints on the design of a software system that autonomously navigates the Ambler through natural terrain using 3-D perception and a combined deliberative/reactive architecture. The software system has required research advances in real-time control, perception of rugged terrain, motion planning, task-level control, and system integration. This paper presents many of the factors that influenced the design of the Ambler and its software system. In particular, important assumptions regarding the mechanism, perception, planning, and control are presented and evaluated in light of experimental and theoretical research of this project.

Ambler - Performance of a six-legged planetary rover

Abstract: In this paper we quantify several performance metrics for the Ambler, a six-legged robot configured for autonomous traversal of Mars-like terrain. We present power consumption measures for walking on sandy terrain and for vertical lifts at different velocities. We document the performance of a novel dead-reckoning approach, and analyze its accuracy. We describe the results of autonomous walking experiments in terms of terrain traversed, walking speed and endurance.

1991 Year End Report Autonomous Planetary Rover

Abstract: This report describes progress in research on an autonomous robot for planetary exploration performed during 1991 at the Robotics Institute, Carnegie Mellon University. The report summarizes the achievements during calendar year 1991, and lists personnel and publications. In addition, it includes several papers resulting from the research. Research in 1991 focused on understanding the unique capabilities of the Ambler mechanism and on autonomous walking in rough, natural terrain. We also designed a sample acquisition system, and began to configure a successor to the Ambler. Understanding Mechanism Capablities In 1991 we concluded an investigation of the interaction between the Ambler and the terrain. This work led to new stability measures, novel force redistribution models, and reactive control schemes. In order to quantify the performance of the Ambler, we measured the power consumption of the Ambler while walking, and while raising and lowering the body. We also calibrated more exactly the kinematics of the mechanism. Autonomous Walking The experimental program in walking on rough terrain continued and expanded. Highlights include the following: 0 Long-term autonomous walking over challenging terrain, including a live demona Autonomous walking outdoors, including night-time navigation. 0 Installation of all computing and electronics on-board the Ambler. stration to sponsors. Sample Acquisition In 1990 we demonstrated sampling capabilities on a testbed separate from the Ambler. In 1991 we designed a sampling system for the Ambler. It consists of a commercial manipulator, a short-range light-stripe sensor, and a storage receptacle. The arm and sensor are mounted on the horizontal link of a leg, rather than underneath a body. This design was not fabricated during 1991 for financial reasons. Configuration of a Successor to the Ambler We began to configure an integrated lander/walker for planetary exploration. This preliminary work is incomplete, and we expect this topic to be one of the central concerns for the research program in 1992.