Cyber-Physical Systems (CPSs) are often safety-critical and deployed in uncertain environments. Identifying scenarios where CPSs do not comply with requirements is fundamental but difficult due to the multidisciplinary nature of CPSs. We investigate the testing of control-based CPSs, where control and software engineers develop the software collaboratively. Control engineers make design assumptions during system development to leverage control theory and obtain guarantees on CPS behaviour. In the implemented system, however, such assumptions are not always satisfied, and their falsification can lead to loss of guarantees. We define stress testing of control-based CPSs as generating tests to falsify such design assumptions. We highlight different types of assumptions, focusing on the use of linearised physics models. To generate stress tests falsifying such assumptions, we leverage control theory to qualitatively characterise the input space of a control-based CPS. We propose a novel test parametrisation for control-based CPSs and use it with the input space characterisation to develop a stress testing approach. We evaluate our approach on three case study systems, including a drone, a continuous-current motor (in five configurations), and an aircraft.Our results show the effectiveness of the proposed testing approach in falsifying the design assumptions and highlighting the causes of assumption violations.

翻译：信息物理系统（CPSs）通常具有安全关键特性，并部署于不确定环境中。识别CPS不满足需求的场景是基础性但具挑战性的任务，其根源在于CPS的多学科交叉特性。本文研究基于控制的CPS测试方法，在该类系统中，控制工程师与软件工程师协同开发软件。控制系统开发过程中，工程师基于控制理论做出设计假设以获取CPS行为的理论保障。然而在实际部署系统中，这些假设并非总能成立，其失效可能导致保障机制的丧失。我们将基于控制的CPS压力测试定义为：通过生成测试用例来证伪此类设计假设。本文重点分析采用线性化物理模型这一典型假设类型，并借助控制理论对基于控制的CPS输入空间进行定性刻画，从而生成能够证伪此类假设的压力测试。我们提出一种针对基于控制的CPS的新型测试参数化方法，并将其与输入空间刻画相结合，开发出完整的压力测试方案。通过在包括无人机、直流电机（五种配置）及飞行器在内的三个案例系统上的实验评估，验证了所提测试方法在证伪设计假设及揭示假设违规原因方面的有效性。