Steven Legowik

Driving autonomously off-road up to 35 km/h

A robotic highly mobile multipurpose wheeled vehicle drives autonomously off-road at speeds up to 35 km/h (10 m/s, 20 mph). The key features of the implementation that enable the vehicle driving at these speeds are: 1) planning the next 20 m with dynamically feasible trajectories; and 2) increasing the lateral clearance to obstacles at higher speeds. Clothoid trajectories are used in planning the vehicles immediate path. The speed-indexed clearance requirement improves the safety margin for the vehicle over a range of speeds while retaining the ability to maneuver in close quarters when necessary.

Repository of sensor data for autonomous driving research

We describe a project to collect and disseminate sensor data for autonomous mobility research. Our goals are to provide data of known accuracy and precision to researchers and developers to enable algorithms to be developed using realistically difficult sensory data. This enables quantitative comparisons of algorithms by running them on the same data, allows groups that lack equipment to participate in mobility research, and speeds technology transfer by providing industry with metrics for comparing algorithm performance. Data are collected using the NIST High Mobility Multi-purpose Wheeled Vehicle (HMMWV), an instrumented vehicle that can be driven manually or autonomously both on roads and off. The vehicle can mount multiple sensors and provides highly accurate position and orientation information as data are collected. The sensors on the HMMWV include an imaging ladar, a color camera, color stereo, and inertial navigation (INS) and Global Positioning System (GPS). Also available are a high-resolution scanning ladar, a line-scan ladar, and a multi-camera panoramic sensor. The sensors are characterized by collecting data from calibrated courses containing known objects. For some of the data, ground truth will be collected from site surveys. Access to the data is through a web-based query interface. Additional information stored with the sensor data includes navigation and timing data, sensor to vehicle coordinate transformations for each sensor, and sensor calibration information. Several sets of data have already been collected and the web query interface has been developed. Data collection is an ongoing process, and where appropriate, NIST will work with other groups to collect data for specific applications using third-party sensors.

High-level mobility controller for a remotely operated unmanned land vehicle

The U.S. Army Laboratory Command, as part of the Department of Defense Robotics Testbed Program, is developing a testbed for cooperative, real-time control of unmanned land vehicles. The program entails the development and integration of many elements which allow the vehicles to perform both autonomous and teleoperated functions. The National Institute of Standards and Technology (NIST) is supporting this program by developing the vehicle control system using the Real-time Control System (RCS) architecture. RCS is a hierarchical, sensory-based control system, initially developed for the control of industrial robots and automated manufacturing systems. NIST is developing the portions of RCS that control all vehicle mobility functions, coordinate the operations of the other subsystems on the vehicle, and communicate between the vehicle and the remote operator control station. This paper reviews the overall control system architecture, the design and implementation of the mobility and communication functions, and results from recent testing.

Control system architecture for a remotely operated unmanned land vehicle

Techbase Enhancements for Autonomous Machines (TEAM) is a joint effort among several US Army organizations, national laboratories, and commercial contractors to develop a vehicle control system that can support a mix of capabilities ranging from master-slave teleoperation to autonomous control. The overall TEAM control system architecture and the design of the mobility and communication functions are described. The architecture is based on the real-time control system (RCS), a hierarchical, sensory-based control system. In this application, RCS controls all vehicle mobility functions, coordinates the operations of the other subsystems on the vehicle, and communicates between the vehicle and the remote operator control station. The functional modules of the control system and their responsibilities are described, with emphasis placed on the modules that support mobility functions. The design of the mobility and communication subsystems and the implementation of the mobility and communication control systems are outlined.<<ETX>>

GPS aided retrotraverse for unmanned ground vehicles

A computer controlled HMMWV automatically retraces a previously recorded path using navigation data, a process we have termed retrotraverse. A Kalman filter combines the output of two navigation systems, an inertial dead reckoning systems and a differential GPS both with and without carrier phase detection. During retrotraverse, the mobility controller uses a velocity controller and pure pursuit steering. Obstacles such as another vehicle can be detected with a laser range imaging device.

Mobile Manipulator Performance Measurement Towards Manufacturing Assembly Tasks

Mobile manipulator performance measurement research is relatively minimal as compared to that of robot arms. Measurement methods, such as optical tracking systems, are useful for measuring the performance of mobile manipulators, although at a much higher relative cost as compared to artifacts. The concept of using test artifacts demonstrates to potential manufacturers and users of mobile manipulator systems that relatively low cost performance measurement methods exist. This paper discusses the concept of reconfigurable mobile manipulator artifacts that were designed and built. An artifact was then used through experimentation to measure the performance of a mobile manipulator to demonstrate the feasibility of the test method. Experimental results show a promising test method to measure the performance of mobile manipulators that are to be used for manufacturing assembly tasks, where at least the mobile manipulator tested has the capability to perform assembly to 1 mm positional accuracy or greater.

Mobile robot and mobile manipulator research towards ASTM standards development

Performance standards for industrial mobile robots and mobile manipulators (robot arms onboard mobile robots) have only recently begun development. Low cost and standardized measurement techniques are needed to characterize system performance, compare different systems, and to determine if recalibration is required. This paper discusses work at the National Institute of Standards and Technology (NIST) and within the ASTM Committee F45 on Driverless Automatic Guided Industrial Vehicles. This includes standards for both terminology, F45.91, and for navigation performance test methods, F45.02. The paper defines terms that are being considered. Additionally, the paper describes navigation test methods that are near ballot and docking test methods being designed for consideration within F45.02. This includes the use of low cost artifacts that can provide alternatives to using relatively expensive measurement systems.