Abstract: A fleet management system for monitoring the tread depth of a plurality of tyres in use in a fleet of vehicles, includes an electronic database of information relevant to the depth of tread for each of a plurality of tyres in use in a fleet of vehicles, an apparatus (100) for testing vehicle tyres, the apparatus (100) including eddy current sensors (120) arranged for detecting the relative position of a metallic reference point within a tyre, and an electronic controller for automatically updating said electronic database in response to test data received from said apparatus (100).

Abstract: A telemetry unit (100) is provided for mounting inside a pneumatic tyre. The unit (100) includes a piezoelectric power generator for supplying power to the unit (100). A piezoelectric element (114) is supported in a housing (112) with an actuator 136 arranged for contact with the element (114), to deflect the element (114) in response to external forces acting on the actuator (136) during rotation of the tyre. For every rotation of the tyre, cyclic pulses of electrical charge are generated by the deflection of the element (114). The charge is stored and utilised under a power consumption protocol to operate pressure and temperature sensors and to transmit data from the unit (100). The telemetry circuitry is mounted for movement with the actuator (136) and therefore contributes to the actuating mass acting on the element (114).

Abstract: A telemetry unit (100) is provided for mounting to the inside of a pneumatic tyre, which includes sensors for measuring the pressure and temperature within the tyre and an RF transmitter for transmitting measured data to an on-board display remote location. The unit (100) includes a piezoelectric element (114) supported in a housing (112) with an actuator (136) arranged for contact with the element (114), to deflect the element (114) in response to external forces acting on the actuator (136) during rotation of the tyre. For every rotation of the tyre, cyclic pulses of electrical charge are generated by the deflection of the element (114). The unit (100) includes control means which controls the consumption of stored charge when measuring and transmitting data and is arranged to vary the rate of transmission of data from the unit (100) in dependance on the rotary speed of the tyre.

Abstract: Low power consumption protocol A telemetry unit (100) is provided for mounting inside a pneumatic tyre, which includes a piezoelectric element (114) supported in a housing (112), with an actuator (136) arranged for contact with the element (114), to deflect the element (114) in response to external forces acting on the actuator (136) during rotation of the tyre. For every rotation of the tyre, cyclic pulses of electrical charge are generated by the deflection of the element (114). The charge is stored and utilised under a power consumption protocol including the steps of: initiating power to a data measurement circuit for measuring data from the environment local to the unit (100); disabling power to the data measurement circuit; initiating power to a data transmission circuit; transmitting data from the measurement circuit; and disabling power to the transmission circuit.