Research On The Key Technologies In The AMS-AIS System Based On A Data-driven Hardware-in-the-loop Simulation Methodology

The Alpha Magnetic Spectrometer(AMS)is a particle physics experiment mounted on the International Space Station,aiming at measuring antimatter in cosmic rays,and searching for evidence of dark matter.The AMS-02 detector is not easily accessible on orbit,and it does not have a complete copy on the ground.In the long duration of AMS-02 which would be over 10 years,the Antimatter Investigation System(AIS)on the ground could be utilized to simulate the flight system,and help investigate the techniques and the methods of particle detection in space,specifically support flight software test,fault diagnosis,and study of particle detection strategies.Combining the hardware-in-the-loop(HIL)method and the data-driven technique,a data-driven hardware-in-the-loop(DDHIL)simulation method is proposed,which provides an ar-chitecture of AIS that is easy to implement.The conventional HIL method is based on mathe-matical models of the simulated system,but the AMS-02 detector consists of many sub-systems and operates in a complex environment,which makes it difficult to build mathematical models.In a DDHIL system,virtual devices are driven by data instead of mathematical models.For complex systems like AMS-02,the DDHIL method could be much more applicable than the conventional HIL method.AMS-02 sub-systems use different communication protocols,which are supposed to be supported in the simulated environment,and a layered modular design is proposed to imple-ment the multi-protocol interface communications between the real hardware and the virtual environment.Based on a multi-protocol interface device,communication functions are im-plemented in separate modules,i.e.,hardware manipulation,communication protocols,data encapsulation,and software applications.Different modules could be configured and invoked separately,therefore this implementation would be flexible,configurable and portable.The basic functional units in a DDHIL simulation system are various data-driven devices,and a fully configurable template providing rich features is constructed to help define data-driven devices.With this template,device status could be simulated if the data source is spec-ified,and optional state variables are introduced to make the virtual devices reply to real con-trollers by recording state changes and switching data sources if needed.To establish the complete DDHIL simulation environment,a procedure is worked out,in-cluding instantiating virtual devices,preparing simulation data,and making the virtual devices interact with real controllers.A domain-specific language is designed to simplify the instan-tiation;a dedicated tool is made to convert the original runtime data into the simulation data format;and the main routine is programmed to organize the simulation.With the DDHIL methodology,AIS has been built up and it has already become a test and verification platform in the investigation of AMS-02 sub-system failures.Several problems were found in the flight software tests,e.g.,alarms were not triggered properly,parameters were not set as expected,the automatic protection executed wrong actions,etc.The corrected software was uploaded to AMS-02 and has been running stably ever since.In comparison to conventional HIL systems which are mostly used for software tests,a DDHIL system also supports long-term maintenance,specifically demonstration of anomalies in daily monitoring,practice of remote operations,fault diagnosis and recovery.The DDHIL methodology has been verified in the AMS-02 experiment,and it would be beneficial to other complex facilities as well.