Vehicle diagnostic system

A vehicle diagnostic system that diagnoses a target vehicle using sound data obtained by recording a sound produced from the target vehicle, the target vehicle being a vehicle to be diagnosed, the vehicle diagnostic system comprising:

• processing circuitry;
• and
• a storage device, wherein
• the storage device stores:
• data of a learned model trained by supervised learning to generate operation data from training sound data using training data including the training sound data and the operation data, the training sound data being recorded while operating a reference vehicle in which no anomaly has occurred, and the operation data indicating an operation status of the reference vehicle collected simultaneously with the training sound data;
• and
• probability distribution data obtained by generating pieces of generated data that is the operation data generated by the learned model using pieces of sound data recorded using vehicles in which types of anomalies are identified and by obtaining, for each of the types of anomalies, a probability distribution of a loss variable indicating a magnitude of an error of each of the pieces of the generated data from the operation data collected simultaneously with the sound data, and
• the processing circuitry is configured to execute:
• a loss calculation process that generates the pieces of the generated data by the learned model using pieces of diagnostic sound data recorded while operating the target vehicle, and obtains data of a probability distribution of a loss variable in the pieces of the generated data as sample data;
• and
• a diagnostic process that determines which probability distribution of an anomaly the sample data matches using the sample data and the probability distribution data, and outputs a diagnosis result indicating that a type of anomaly corresponding to the probability distribution that is determined to match the sample data has occurred in the target vehicle.