Event-driven displays for manipulator control

The problem of constructing event-related information displays from multidimensional data generated by proximity, force-torque and tactile sensors integrated with the terminal device of a remotely controlled manipulator is considered. Event-driven displays are constructed by using appropriate algorithms acting on sensory data in real time. Event-driven information displays lessen the operator's workload and improve control performance. The paper describes and discusses several event-driven display examples that were implemented in the JPL teleoperator project, including a brief outline of the data handling system which drives the graphics display in real time. The paper concludes with a discussion of future plans to integrate event-driven displays with visual (TV) information

Displays for supervisory control of manipulators

The problem of displaying information generated by sensors attached to the terminal device of a remotely controlled manipulator is considered. The sensors under consideration are proximity, force-torque, tactile and slip-page sensors. The paper describes and evaluates several examples that have been implemented in the JPL teleoperator project using audio and graphic displays of information generated by four proximity sensors attached to a manipulator end effector. Design schemes are also discussed related to the display of information generated by a six-dimensional force-torque sensor, a multipoint proportional tactile sensor, and a directional slippage sensor. The paper concludes with a discussion of future integrated displays of visual (TV) and handbased sensor information

Shallow Seismic Data Acquisition, Processing, and Interpretation at Playa 5, Carson County, Texas

Seismic methods were used to determine the physical properties and geological development of Playa 5, a playa basin located on the U.S. Department of Defense's former Pantex Ordnance Plant, for comparison with results from other basins (Sevenmile Basin, Pantex Playa 3, and Pantex Lake) as well as with results from seismic data collected in interplaya areas. These studies have led to a better understanding of stratigraphic differences between playa basins, which serve as preferential recharge points for the Ogallala aquifer, and between playa and unaltered interplaya areas, where little Ogallala recharge is thought to occur. Playa 5 is a nearly circular playa that is 0.7 to 0.9 km across. It is enclosed by a basin that is about 2 km across and has 5 m of relief between the highest and lowest closed elevation contours. Refraction surveys show that the surface layer at Playa 5 is a few meters thick and has typical seismic velocities of 420 to 440 m/s. This layer is underlain by a layer with higher seismic velocities of 808 to 910 m/s that has similar texture but more pedogenic carbonate. Refraction methods also detected a layer at more than 60-m depth with significantly higher seismic velocities of about 2000 m/s. This layer probably represents a competent horizon above the modern Ogallala water table that has been cemented by either pedogenic or hydrologic processes. Reflection data collected across Playa 5 show that relief on seismic horizons increases with age. Modern surface relief is 6 m, which increases to 30 m on a horizon that is interpreted to be correlative to a fine-grained zone that perches groundwater beneath parts of the Pantex Plant. Relief increases to 50 m on a horizon that is interpreted to be the top of Permian or Triassic bedrock. Internal bedrock reflectors dip toward the basin center beneath the playa, suggesting that subsidence related to dissolution of underlying Permian salt has contributed to the development of the Playa 5 basin. Playa 5 subsidence has occurred at average rates of 0.33 to 0.42 m per meter of deposition, rates that are similar to those at Playa 3 and Pantex Lake and are less than half those inferred for Sevenmile Basin.Bureau of Economic Geolog

Geophysical imaging of possible faulted strata near Matagorda, Texas

We utilized ground-penetrating radar (GPR) and shallow seismic reflection methods to image the shallow subsurface across the surface trace of the suspected fault crossing tidal flats, marshes, and open water on Matagorda Peninsula near Matagorda, Texas. The fault is believed to be the potential surface expression of a deeper gulfward-dipping growth fault cutting through Cenozoic strata.Bureau of Economic Geolog

Identifying and Assessing Ground Water in the Lower Rio Grande Valley, Texas Using Airborne Electromagetic Induction

- Airborne EM can be used to explore to depths of 150 to 300m in fresh to moderately saline coastal plain aquifers. - Airborne EM surveys are a realistic alternative to drilling and seismic surveys to investigate Quaternary depositional systems. - Groundwater quality (as measured by TDS) appears to correlate to conductivity derived from airborne EM data. - Depositional patterns can be detected and environments inferred from airborne EM if the surveys are flown at appropriate line spacing and orientation. - Anomaly shapes and conductivity contrasts can be used to interpret likely water resource quality by combining geological and hydrological concepts.Bureau of Economic Geolog

Shallow Seismic Studies of an Ephemeral Lake (Playa A) Basin on the Southern High Plains, Texas Panhandle

Shallow seismic data collected at Sevenmile Basin, a large ephemeral lake (playa) basin in the Texas Panhandle, reveal that subsidence has been an important agent in the formation of the basin. Several hypotheses have been considered for the origin of thousands of playa basins on the Southern High Plains of Texas and New Mexico, including eolian deflation, evaporite or carbonate dissolution and subsidence, piping, and animal activity. Seismic methods, adapted to investigations in the shallow subsurface (200 m or less), provide data that indicate subsidence caused by evaporite dissolution is the most important of these mechanisms at Sevenmile Basin. Sevenmile Basin is 5.5 by 3.6 km across and 14 m deep and is inset into the Quaternary Blackwater Draw Formation. The Blackwater Draw overlies the upper Tertiary Ogallala Formation, which hosts the economically important Ogallala aquifer. Shallow seismic refraction and reflection data were collected from this unconsolidated and variably saturated elastic sequence to understand the physical properties, geological history, and hydrogeological framework of playa basins, which are the principal recharge areas for the Ogallala aquifer.Bureau of Economic Geolog

Seismic Reflection, Refraction, and Surface Wave Studies at the Proposed Low-Level Radioactive Waste Repository, Hudspeth County, Texas

Seismic reflection, refraction, and surface wave methods were employed to characterize the shallow subsurface at the proposed low-level radioactive waste repository site located on Faskin Ranch about 5 miles (8 km) southeast of Sierra Blanca, Texas. Reversed seismic refraction data were used to (1) determine near-surface compressional velocities for elevation datum corrections, (2) obtain preliminary velocity profiles for processing seismic reflection data, and (3) obtain depth-to-bedrock estimates. Seismic reflection data were used to determine basin geometry beneath the site, depth to bedrock, and internal basin-fill stratigraphy. Surface waves were analyzed to generate shear-wave-velocity models of the shallow subsurface. Seismic reflection, refraction, and surface wave data were acquired in May and June of 1992 using a 500-lb (230-kg) accelerated weight drop seismic source, a 48-channel seismograph, and an acquisition crew supplied by the Bureau of Economic Geology (BEG) and The University of Texas at El Paso (UTEP). Refraction data were collected at six sites on Faskin Ranch and were processed and analyzed at BEG. Nearly 3.9 miles (6.2 km) of seismic reflection data were collected along one line oriented northwest-southeast across the site and three crossing lines oriented northeast-southwest. These data were processed and analyzed at both BEG and UTEP. Surface wave data were collected near the center of the proposed repository and were processed and analyzed at UTEP.Bureau of Economic Geolog

Shallow Seismic Data Acquisition, Processing, and Interpretation at Playa 3, Pantex Plant, Carson County, Texas

Shallow seismic refraction and reflection data were collected in 1993 at Pantex Playa 3, a small (0.5-kilometer diameter), nearly circular ephemeral lake near the northern boundary of the Pantex Plant, as part of a hydrogeological study of the Pantex area playa and interplaya environments. These studies will be used to help understand the hydrogeological framework of the Pantex Plant and the paths of groundwater and potential contaminants in the subsurface. Seismic refraction data collected along two reversed spreads show that near-surface compressional velocities increase from less than 400 meters per second at the surface to 700 to 1200 meters per second a few meters below the surface. Two shallow seismic reflection lines across Playa 3, each 1.8 kilometers long, reveal the presence of four major reflecting horizons beneath the playa basin. Horizon 0, the shallowest, is interpreted to be from the Ogallala caprock and appears to be absent directly beneath Playa 3. Horizon 1 is interpreted as a fine-grained zone within the upper Ogallala Formation that may perch groundwater above the main Ogallala aquifer. Horizon 2, the strongest reflector on the seismic sections, is a lower Ogallala reflector that may be either a stratigraphic unit or a horizon related to past Ogallala water levels. Horizon 3, the deepest major reflector recognized, is interpreted to be the top of Permian or Triassic bedrock. Each horizon visible on the reflection lines mimics surface topography. Relief increases with depth: the playa floor is 8 meters below the upland, Horizon 0 (caprock) has 16 to 24 meters of relief, Horizon 1 (upper Ogallala fine-grained zone) has 30 meters of relief, Horizon 2 (lower Ogallala reflector) has 35 meters of relief, and Horizon 3 (bedrock) has 75 meters of relief. Increasing relief with age, coupled with the presence of internal bedrock reflectors that dip toward the basin center beneath the margins of Playa 3, indicate that subsidence has been important in the formation of the basin. Subsidence is probably caused by dissolution of underlying Permian evaporites.Bureau of Economic Geolog

Establishing Acceptable Ground Motion at the TDA Metrology Laboratory, Austin, Texas

In August 2001, researchers at the Bureau of Economic Geology (Bureau) conducted a geophysical investigation for the Texas Department of Agriculture (TDA) to establish vibration characteristics at the Metrology Laboratory (Figure 1) for future comparison with proposed sites. We employed a vibration-monitoring instrument to establish ground-motion characteristics at the laboratory under a representative range of conditions. Tasks included recording ground motion at the laboratory, analyzing recorded data to determine velocities, accelerations, and frequency characteristics in the vertical and horizontal directions, and comparing ground motion recorded inside and outside the laboratory under representative conditions.Bureau of Economic Geolog

Airborne geophysical assessment of salinization in the Lacy Creek area, Sterling County, Texas

In late August and early September 2001, a high-resolution airborne geophysical survey was flown over a 162 km2 area west of Sterling City in Sterling County, Texas. This survey, flown to delineate salinization and estimate its intensity in the shallow, relatively fresh groundwater of the alluvial and Antlers aquifers, acquired magnetic field data to aid the identification of oil and gas wells and electromagnetic (EM) induction data to reveal the electrical conductivity of the ground to depths of 150 m or more. We used water well data from the Texas Water Development Board (TWDB) database and oil and gas well locations from the Texas Railroad Commission (RRC) to assess the accuracy and usefulness of the magnetic field and ground conductivity data. Additionally, we collected ground conductivity data along several transects using a ground-based conductivity meter. We used these data to design the airborne survey, anticipate airborne exploration depths, select the appropriate airborne instruments, compare airborne and ground-based measurements over the same area, and investigate evidence for salinization at several representative locations. We combined aerial photographs, oil and gas well data, water well data, and airborne and ground-based geophysical data in a geographic database (GIS) to facilitate analysis of geophysical anomalies and determine the relationship between water properties and geophysical measurements.Bureau of Economic Geolog