Summary form only given. We discuss the unique architectural elements of the Los Alamos message passing interface (LA-MPI), a high-performance, network-fault-tolerant, thread-safe MPI library. LA-MPI is designed for use on terascale clusters which are inherently unreliable due to their sheer number of system components and trade-offs between cost and performance. We examine in detail the design concepts used to implement LA-MPI. These include reliability features, such as application-level checksumming, message retransmission, and automatic message rerouting. Other key performance enhancing features, such as concurrent message routing over multiple, diverse network adapters and protocols, and communication-specific optimizations (e.g., shared memory) are examined.

The Los Alamos Message Passing Interface (LA-MPI) is an end-to-end network-failure-tolerant message-passing system designed for terascale clusters. LA-MPI is a standard-compliant implementation of MPI designed to tolerate network-related failures including I/O bus errors, network card errors, and wire-transmission errors. This paper details the distinguishing features of LA-MPI, including support for concurrent use of multiple types of network interface, and reliable message transmission utilizing multiple network paths and routes between a given source and destination. In addition, performance measurements on production-grade platforms are presented.

This paper describes the analysis and implementation of a motor drive control system for an intelligent wheelchair being developed at the Robotics Institute at Carnegie-Mellon University. The experimental mobile platform is mounted on four so-called Ilonators which permit motion in any direction without conventional steering of the wheel axes. The kinematics of the platform were determined analytically and a simulation program was developed to generate reference wheel velocity trajectories corresponding to several basic platform trajectories. These reference trajectories were used to drive the platform under open-loop control. The paper includes a description of the motor-drive hardware implementation, and experimental results. The results of this work provide the foundation for the implementation of feedback control of the wheels and higher-level supervisory control.