Engineering topics
Peng, Chia-Yen
Publications and source records attributed to Peng, Chia-Yen.
End to End Simulation of the Mars 2020 Rover Mobility Deployment and Touchdown
No abstract available
Development of MSL Rover Loads by Integrated ADAMS-GNC Skycrane Simulation
No abstract available
Determining Wheel-Soil Interaction Loads Using a Meshfree Finite Element Approach Assisting Future Missions with Rover Wheel Design
A wheel experiencing sinkage and slippage events poses a high risk to rover missions as evidenced by recent mobility challenges on the Mars Exploration Rover (MER) project. Because several factors contribute to wheel sinkage and slippage conditions such as soil composition, large deformation soil behavior, wheel geometry, nonlinear contact forces, terrain irregularity, etc., there are significant benefits to modeling these events to a sufficient degree of complexity. For the purposes of modeling wheel sinkage and slippage at an engineering scale, meshfree finite element approaches enable simulations that capture sufficient detail of wheel-soil interaction while remaining computationally feasible. This study demonstrates some of the large deformation modeling capability of meshfree methods and the realistic solutions obtained by accounting for the soil material properties. A benchmark wheel-soil interaction problem is developed and analyzed using a specific class of meshfree methods called Reproducing Kernel Particle Method (RKPM). The benchmark problem is also analyzed using a commercially available finite element approach with Lagrangian meshing for comparison. RKPM results are comparable to classical pressure-sinkage terramechanics relationships proposed by Bekker-Wong. Pending experimental calibration by future work, the meshfree modeling technique will be a viable simulation tool for trade studies assisting rover wheel design.
Development of MSL Rover Loads by ADAMS Skycrane Simulation
No abstract available
System Verification of MSL Skycrane Using an Integrated ADAMS Simulation
Mars Science Laboratory (MSL) will use the Skycrane architecture to execute final descent and landing maneuvers. The Skycrane phase uses closed-loop feedback control throughout the entire phase, starting with rover separation, through mobility deploy, and through touchdown, ending only when the bridles have completely slacked. The integrated ADAMS simulation described in this paper couples complex dynamical models created by the mechanical subsystem with actual GNC flight software algorithms that have been compiled and linked into ADAMS. These integrated simulations provide the project with the best means to verify key Skycrane requirements which have a tightly coupled GNC-Mechanical aspect to them. It also provides the best opportunity to validate the design of the algorithm that determines when to cut the bridles. The results of the simulations show the excellent performance of the Skycrane system.
Incorporation of Uncertainties in the Mars Science Laboratory Rover Loads Analysis
No abstract available
A 'Super Bowl' Approach to Mars Rover Touchdown Loads Analysis
Touchdown Driving Requirement: The mechanical system surface element shall be capable of facilitating a safe, stable landing at terrain angles up to 15 degrees, given an initial vertical velocity of 1 m/sec, horizontal velocity of 0.5 m/sec, and Z-axis spin rate of [4] deg/sec.Touchdown Loads Development: A multi-year development effort has been successfully conducted leading to an innovative analytical methodology for the prediction of rover touchdown design loads and the assessment of rover touchdown stability.
Measurement of vibrational damping at cryogenic temperatures for silicon carbide foam and silicon foam materials
The Terrestrial Planet Finder mission requires extreme dynamic stability at cryogenic temperatures in order to carry out its objectives of searching for and observing extraterrestrial planets.
Experimental Observations on Material Damping at Cryogenic Temperatures
This paper describes a unique experimental facility designed to measure damping of materials at cryogenic temperatures for the Terrestrial Planet Finder (TPF) mission at the Jet Propulsion Laboratory. The test facility removes other sources of damping in the measurement by avoiding frictional interfaces, decoupling the test specimen from the support system, and by using a non-contacting measurement device. Damping data reported herein are obtained for materials (Aluminum, Aluminum/Terbium/Dysprosium, Titanium, Composites) vibrating in free-free bending modes with low strain levels (< 10(exp -6) ppm). The fundamental frequencies of material samples are ranged from 14 to 202 Hz. To provide the most beneficial data relevant to TPF-like precision optical space missions, the damping data are collected from room temperatures (around 293 K) to cryogenic temperatures (below 40 K) at unevenly-spaced intervals. More data points are collected over any region of interest. The test data shows a significant decrease in viscous damping at cryogenic temperatures. The cryogenic damping can be as low as 10(exp -4) %, but the amount of the damping decrease is a function of frequency and material. However, Titanium 15-3-3-3 shows a remarkable increase in damping at cryogenic temperatures. It demonstrates over one order of magnitude increase in damping in comparison to Aluminum 6061-T6. Given its other properties (e.g., good stiffness and low conductivity) this may prove itself to be a good candidate for the application on TPF. At room temperatures, the test data are correlated well with the damping predicted by the Zener theory. However, large discrepancies at cryogenic temperatures between the Zener theory and the test data are observed.
Test Verification of the Cassini Spacecraft Dynamic Model
The Cassini spacecraft mission to Saturn will be launched in October 1997, on a Titan IV/Centaur launch vehicle. Cassini is the largest interplanetary spacecraft ever developed. Before launch approval can be obtained, a test verified finite element model of the Cassini spacecraft must be completed and approved by NASA. The correctness of this model is critical to the final verification coupled loads analysis and margin of safety assessments.
Mars Pathfinder Cruise Stage/Entry Vehicle Separation Dynamics
Prior to atmospheric entry, Mars Pathfinder flight system will separate its entry vehicle from its cruise stage, and establish the entry conditions for a passive and unconventional entry, descent, and landing approach. This paper summarizes a separation dynamics analysis conducted to demonstrate that the cruise separation system design is viable and ensure that adequate design margins exist with the effects from parameter uncertainty included.