Engineering topics

Bryant, Richard B., Jr.

Publications and source records attributed to Bryant, Richard B., Jr..

3 records

NASA NTRS2006

Software Tools for Developing and Simulating the NASA LaRC CMF Motion Base

The NASA Langley Research Center (LaRC) Cockpit Motion Facility (CMF) motion base has provided many design and analysis challenges. In the process of addressing these challenges, a comprehensive suite of software tools was developed. The software tools development began with a detailed MATLAB/Simulink model of the motion base which was used primarily for safety loads prediction, design of the closed loop compensator and development of the motion base safety systems1. A Simulink model of the digital control law, from which a portion of the embedded code is directly generated, was later added to this model to form a closed loop system model. Concurrently, software that runs on a PC was created to display and record motion base parameters. It includes a user interface for controlling time history displays, strip chart displays, data storage, and initializing of function generators used during motion base testing. Finally, a software tool was developed for kinematic analysis and prediction of mechanical clearances for the motion system. These tools work together in an integrated package to support normal operations of the motion base, simulate the end to end operation of the motion base system providing facilities for software-in-the-loop testing, mechanical geometry and sensor data visualizations, and function generator setup and evaluation.

Bryant, Richard B., Jr.↗

NASA NTRS2006

Evaluating the Performance of the NASA LaRC CMF Motion Base Safety Devices

This paper describes the initial measured performance results of the previously documented NASA Langley Research Center (LaRC) Cockpit Motion Facility (CMF) motion base hardware safety devices. These safety systems are required to prevent excessive accelerations that could injure personnel and damage simulator cockpits or the motion base structure. Excessive accelerations may be caused by erroneous commands or hardware failures driving an actuator to the end of its travel at high velocity, stepping a servo valve, or instantly reversing servo direction. Such commands may result from single order failures of electrical or hydraulic components within the control system itself, or from aggressive or improper cueing commands from the host simulation computer. The safety systems must mitigate these high acceleration events while minimizing the negative performance impacts. The system accomplishes this by controlling the rate of change of valve signals to limit excessive commanded accelerations. It also aids hydraulic cushion performance by limiting valve command authority as the actuator approaches its end of travel. The design takes advantage of inherent motion base hydraulic characteristics to implement all safety features using hardware only solutions.

Gupton, Lawrence E.↗

NASA NTRS2005

Mitigating Motion Base Safety Issues: The NASA LaRC CMF Implementation

The NASA Langley Research Center (LaRC), Cockpit Motion Facility (CMF) motion base design has taken advantage of inherent hydraulic characteristics to implement safety features using hardware solutions only. Motion system safety has always been a concern and its implementation is addressed differently by each organization. Some approaches rely heavily on software safety features. Software which performs safety functions is subject to more scrutiny making its approval, modification, and development time consuming and expensive. The NASA LaRC's CMF motion system is used for research and, as such, requires that the software be updated or modified frequently. The CMF's customers need the ability to update the simulation software frequently without the associated cost incurred with safety critical software. This paper describes the CMF engineering team's approach to achieving motion base safety by designing and implementing all safety features in hardware, resulting in applications software (including motion cueing and actuator dynamic control) being completely independent of the safety devices. This allows the CMF safety systems to remain intact and unaffected by frequent research system modifications.

Bryant, Richard B., Jr.↗