Road surface state determination device and tire system including same

A road surface state determination device comprising:

• a tire-side device attached to each of a plurality of tires included in a vehicle;
• and
• a vehicle-body-side system included in a body of the vehicle, wherein:
• the tire-side device includes
• a vibration detector configured to output a detection signal corresponding to a magnitude of vibration of the tire,
• a processor and a memory configured to sense the detection signal and generate road surface data indicative of a road surface state appearing in a waveform of the detection signal, and
• a first data communication unit configured to transmit the road surface data;
• the vehicle-body-side system includes
• a second data communication unit configured to perform bidirectional communication with the first data communication unit of the tire-side device by wireless communication based on BLUETOOTH Low Energy, and receive the road surface data transmitted from the first data communication unit, and
• a processor and a memory configured to determine the road surface state of a road surface on which the vehicle is traveling based on the road surface data;
• the vehicle-body-side system processor further configured to determine a signal processing condition for the detection signal, and transmit instruction data indicative of the determination to the tire-side device through the wireless communication between the second data communication unit and the first data communication unit;
• and
• the tire-side device processor further configured to receive the instruction data through the wireless communication between the first data communication unit and the second data communication unit, and set the signal processing condition based on the instruction data,
• wherein
• the vehicle-body-side system processor determines, as the signal processing condition, an arithmetic condition for calculating a feature quantity indicative of a feature of the vibration of the tire and a weighting correction factor for calculating the feature quantity by a weighting arithmetic operation and causes the second data communication unit to transmit, as the instruction data, the determination of the signal processing condition,
• the tire-side device processor acquires the feature quantity by performing the signal processing of the detection signal based on the signal processing condition,
• the tire-side device processor generates the road surface data including the feature quantity,
• the vehicle-body-side system processor stores support vectors for each type of the road surface, compares feature quantity included in the road surface data transmitted from the tire-side device with the support vectors for each type of the road surface stored in advance, and determines the road surface state of the road surface on which the vehicle is travelling, and
• wherein the feature quantity indicative of a feature of the vibration of the tire represents the feature quantity for one rotation of the tire, in a form of a determinant.

A road surface state determination device comprising:

• a tire-side device attached to each of a plurality of tires included in a vehicle;
• and
• a vehicle-body-side system included in a body of the vehicle, wherein:
• the tire-side device includes
• a vibration detector configured to output a detection signal corresponding to a magnitude of vibration of the tire,
• a processor and a memory configured to sense the detection signal and generate road surface data indicative of a road surface state appearing in a waveform of the detection signal, and
• a first data communication unit configured to transmit the road surface data;
• the vehicle-body-side system includes
• a second data communication unit configured to perform bidirectional communication with the first data communication unit of the tire-side device by wireless communication based on BLUETOOTH Low Energy, and receive the road surface data, and
• a processor and a memory configured to determine the road surface state of a road surface on which the vehicle is traveling based on the road surface data;
• the vehicle-body-side system processor further configured to determine a communication frequency for transmitting the road surface data and transmit instruction data indicative of the communication frequency to the tire-side device through the wireless communication between the second data communication unit and the first data communication unit;
• the tire-side device processor further configured to receive the instruction data through the wireless communication between the first data communication unit and the second data communication unit, and set the communication frequency based on the instruction data;
• and
• the communication frequency is set to be equal to a frequency of sensing of the detection signal by the vibration detector,
• wherein
• when it is determined that the vehicle is about to make a lane change, both the communication frequency and the frequency of sensing increase greater than a reference value.