Reliability-Based Design Opitimization For Harmonic Gear Reducer Of The Solar Array Drive Assembly

Harmonic gear reducer is one of the most important parts in solar array driveassembly (SADA), mainly made up of a flexspline, rigidity gear and harmonic generator.In the design, manufacturing process and using environmental of the harmonic gearreducer there are many uncertainties. Currently, safety-factor method is the usual designmethod. However, the determination of the safety factor is subjective. Further, the safetydegree can not be expressed and the impact on the system performance due to theuncertainty of design variables and parameters can also not be described.Because of this, the armonic gear reducer is taken as the study objective. A staticstate reliability-based design optimization (RBDO) model with the mixture of randomand interval variable and a dynamic RBDO model with considering strengthdegradation are proposed baseing on depth analysising the uncertainty factors. Thesequentail single loop method is used to handle the RBDO model and the quasi-MonteCarlo method is uesd to handle the reliabllity-based sensitivity. This paper’s maincontributions are summaried as follow:(1) The knowledge of the harmonic gear reducer which including the basicprinciple of the harmonic gear drive, composition, classification and characteristics andso on is introduced in detail on the basis of extensive literature review. The researchstatus of the harmonic gear drive at home and abroad is summarized. Besides, theproblems of the research status are also summarized.(2) The sequentail single loop method which using to handle the RBDO modelwith the mixture of random and interval variable are introduced. The basic idea of thesequentail single loop method is to employ a series of cycles of deterministicoptimization and reliability analysis basing on an inverse reliability problem. It willimprove the computational effciency by using the sequentail single loop method.(3) The uncertainties which existing in the harmonic gear reducer’s designning,manufacturing and application environment are quantified. Because of the epistemicuncertainty and aleatory uncertainty’s existing, using the interval variables and randomvariables to quantify the uncertainties in the proposed method (4) In this paper, a RBDO model which considering both epistemic uncertainty andaleatory uncertainty is developed. According to Matlab optimazition program, thesequentail single loop method is used to sloving the optimazition problem. The mostsensitive design parameters to affect the harmonic gear transmission reliability werefounded out by the quasi-Monte Carlo reliabllity-based sensitivity method.(5) The strength degradation is described by the Gamma process. Then, a RBDOmodel with considering the strength degradation for the harmonic gear reducer isproposed. Then, the results analysis is also conducted.