## 1 Introduction
In order to further improve test efficiency, reduce the test sample size and apply to more kinds of products, scholars have expanded the research content from single stress level selection to more test factors. [PERSON] [17] and [PERSON] [18] researched the ADT optimization method for the degradation process following a gamma process. [PERSON] [19] researched an optimal sample ratio under each sample size and the influence of each stress on the objective function. [PERSON] [20] researched the optimal stress level change time in SSADT, and [PERSON] [21] determined the optimal sample size under each stress level, based on different expected utility functions. [PERSON] [22; 23] researched the optimization design method of an ADT scheme for multiple degradation processes under multiple stresses using a simulation method. [PERSON] [24] researched the optimization design method of ADT when prior information is insufficient, and used the information theory to dynamically modify the test scheme, which effectively shortened the test time. [PERSON] [25] proposed a new optimization criterion, which pays more attention to the equivalence of the degradation mechanism, rather than the evaluation accuracy and prediction accuracy. The optimization results of the criterion were compared with the existing criteria. The results showed that the criterion can effectively reduce the stress distance between the normal stress level and the higher stress level, and caused the test arrangement to be more in line with the practical application. For an object with an uncertain degradation mechanism, [PERSON] [26] used the competitive failure model to research the optimization method of ADT schemes for products with multiple failure mechanisms, and optimized the established model by using three conventional optimization criteria (\(D\)-optimality, a-optimality and v-optimality). The results showed that the optimal scheme under random impact was very different from the traditional ADT optimization scheme. [PERSON] [27] and others have also carried out research on this kind of object. They proposed an improved Bayesian \(D\)-optimality criterion to solve this kind of problem, and verified the effectiveness of the method through simulations. In order to maximize the efficiency of the ADT test, [PERSON] [28] optimized the test method to maximize the test stress, and took carbon film resistors as an example to verify the effectiveness of the method. [PERSON] [29] mixed ALT and ADT to reduce test costs to the greatest extent while ensuring accuracy. [PERSON] [30] proposed a multi-stress and multi-degradation ADT optimization design method to solve the problem that the existing single degradation measure ADT cannot be applied to expensive and high reliability products. The proposed method, with the evaluation accuracy of the optimization scheme as the optimization objective, along with the stress, stress level, sample size, detection interval and detection time as the optimization variables, the detection time and cost as the constraints, and the product with multiple degradation measures, was studied, and the effectiveness of the method was verified using a rubber sealed O-ring. However, the above literature regarding the optimization of multi-stress ADT are all about the stress level, sample size, test time and degradation mode. Instead of considering the effect of different stresses on the product, the multiple stresses were directly optimized with the same influence value or influence weight, which leads to the problem of low evaluation accuracy of model parameters of important stresses when using the degradation data generated by the optimized scheme for reliability evaluations. In addition, the main examples of the above ADT scheme optimization methods are electronic components or mechanical products with simple structures, and there are no complex mechanical and electrical products, such as motorized spindles.