Numerical Simulation and Influence of Non-Gaussian Vibrations on the Design of Flexible Robotic Systems

Random vibration excitation is a widely used method to obtain dynamic properties of structures and is commonly applied as a loading condition for aerospace structures. Random vibration spectra are defined most commonly through a power spectral density (PSD) curve which provides the magnitude of the excitation as a function of frequency. A typical analysis for the vibrational response of structures designed with aerospace applications is the application of a predefined PSD curve representing vibrations from launch, landing, or operation. Shakerbased random excitation and traditional finite element analysis techniques employ random vibrations assuming a Gaussian distribution of excitation impulse magnitudes. In reality, while some vibrational environments may be adequately described by Gaussian signals, many true excitations have non-Gaussian properties. A non-Gaussian signal is one that has a skewness or kurtosis not aligned with typical values of a Gaussian distribution. Non-Gaussian random vibrations contain vibrational impulses magnitudes larger than those found in a Gaussian signal and could damage a system if not considered. Flexible systems, notably flexible robotic systems, often manifest dynamic nonlinearities which may produce magnified responses to these impulses. This paper examines two case studies of robotic rover chassis architectures: NASA JPL’s Pop-Up Flat Folding Explorer Robot (PUFFER) and Cooperative Autonomous Distributed Robotic Explorer (CADRE). PUFFER has a flexible architecture and CADRE has a rigid chassis. The influence of non-Gaussian random vibrations on each system is examined and results are presented to aid in the design of flexible robotic systems. The results indicate that Non-Gaussian excitation should be considered in the design of flexible robotic systems and that a typical enveloping procedure, such as a 3dB increase of the input PSD for a Gaussian random vibe excitation, did not bound the response of PUFFER subjected to a non-Gaussian excitation.