RV减速器高应力加速退化试验及可靠性分析

High stress accelerated degradation test and reliability analysis of RV reducer

摘要:

针对工业机器人上使用的RV减速器寿命长且性能退化缓慢的特点,提出一种基于RV减速器高应力加速退化试验与传动精度退化模型建模的方法,对RV减速器可靠性进行评估。对RV减速器薄弱环节的强度进行校核,确定加速试验最大加载值；在该加载值下对3台RV减速器开展加速退化试验,获得加速条件下RV减速器传动精度退化量；根据RV减速器传动精度退化特性,使用样本数据分离的极大似然估计法,对每台减速器的传动精度展开退化轨迹建模；将Wiener退化模型中的初始性能退化量和漂移系数设为定值,获得扩散系数的变异系数,假设扩散系数服从正态分布,求得RV减速器可靠性。结果表明:高应力加速退化试验可为RV减速器可靠性分析提供切实可信的试验数据,节约试验时间及成本。基于加速退化试验和传动精度退化模型建模的求解RV减速器可靠性的方法,在体现个体差异的同时,实现了小样本条件下RV减速器的可靠性分析,并且能够准确计算出RV减速器的失效概率,对于提升工业机器人的工作性能具有重要意义。

Abstract:

In view of the long life and slow degradation of RV reducers used in industrial robots, a method is proposed to evaluate the reliability of RV reducers based on the high stress accelerated degradation test and the modeling of transmission accuracy degradation. The maximum loading value of the accelerated test is determined by strength verification of the weak links. To obtain the degradation amount of the RV reducer transmission accuracy, the accelerated degradation test is conducted on three RV reducers under this loading value. According to the degradation characteristics of the RV reducer transmission accuracy, the degradation trajectory of the transmission accuracy of each reducer is modeled by using the maximum likelihood estimation method with sample data separation. The initial performance degradation and drift coefficient in the Wiener degradation model are set as constant values, and the coefficient of variation of the diffusion coefficient is obtained, assuming that the diffusion coefficient obeys normal distribution to find the reliability of the RV reducer. The results show that the high stress accelerated degradation test can provide reliable test data for RV reducer reliability analysis and save test costs. The proposed method can realize the reliability analysis of RV reducer under small sample conditions while reflecting individual differences, and can accurately calculate the failure probability of RV reducer, which is important for improving the working performance of industrial robots.