Engine state detection device
A device for collecting vehicle on-board diagnostics (OBO) data is disclosed, together with an associated method of collecting OBD data in such devices. In embodiments, the OBO data collection device includes a connector for connecting the device to a vehicle OBO port to receive OBO data and power and a processor for controlling collection of the OBO data. The processor is arranged to determine a vehicle engine state by monitoring a voltage at the connector, taken in combination with OBO data relating to vehicle speed and/or engine revolutions. Such devices are able to reliably detect both engine ‘on’ and ‘off’ states in modern vehicles that use “smart charging” technology.
1. A device for detecting a state of a vehicle's engine using vehicle on-board diagnostics (OBD) data, the device comprising:
a connector for connecting the device to a vehicle OBD port to receive OBD data and power; and
a processor arranged to determine a vehicle engine state by monitoring a voltage at the connector, the processor:
(i) detecting an engine ‘on’ state from a temporary voltage drop of at least a predetermined magnitude; and
(ii) detecting an engine ‘off’ state by:
detecting a pending engine ‘off’ state from a voltage value that is less than a threshold;
confirming the pending engine ‘off’ state from the OBD data indicating at least one of vehicle speed and engine revolutions are at a constant non-zero value for a first predetermined time period; and
detecting a final engine ‘off’ state after a second predetermined time period; and
based on detecting the engine ‘off’ state, changing a level of operation of the device from a running mode to a sleep mode, wherein, in the sleep mode, no power is drawn by the device from the ODB port.
2. The device according to claim 1 , wherein the processor is arranged to detect the pending engine ‘off’ state from a voltage value that is less than the threshold for a third predetermined time period.
3. The device according to claim 2 , wherein the third predetermined time period is at least 1 second.
4. The device according to claim 1 , wherein the threshold is at least 13 volts.
5. The device according to claim 1 , wherein the first predetermined time period is at least 5 seconds.
6. The device according to claim 1 , wherein the second predetermined time period is at least 10 seconds.
7. The device according to claim 1 , where the processor is arranged to detect the engine ‘on’ state from a temporary voltage drop of at least 2 volts.
8. The device according to claim 1 , where the processor is arranged to detect the engine ‘on’ state from a temporary voltage drop of at least a predetermined magnitude that lasts for a time period of less than 1 second.
9. The device according to claim 1 , wherein the processor is arranged to detect the engine ‘on’ state by sampling the voltage at the connector at a frequency of at least 8 Hz.
10. The device according to claim 1 , wherein the processor is arranged to control collection of the OBD data by at least one of: starting the collection of the OBD data when the engine ‘on’ state is detected; and by stopping the collection of the OBD data when the final engine ‘off’ state is detected.
11. The device according to claim 1 , wherein the processor is arranged to use the determined vehicle engine state to set a start and an end of a trip, so as to determine a trip duration.
12. The device according to claim 1 , wherein the processor is arranged to, based on detecting the engine ‘on’ state, change a level of operation of the device from a sleep mode to a running mode.
13. A non-transitory computer readable medium comprising computer readable instructions that, when executed by at least one processor of a device having a connector for connecting the device to a vehicle OBD port, causes the device to perform a method comprising:
receiving OBD data and power from the vehicle OBD port;
determining a vehicle engine state by monitoring a voltage at the connector, said determining comprising:
(i) detecting an engine ‘on’ state from a temporary voltage drop of at least a predetermined magnitude; and
(ii) detecting an engine ‘off’ state by:
detecting a pending engine ‘off’ state from a voltage value that is less than a threshold;
confirming the pending engine ‘off’ state from the OBD data indicating at least one of vehicle speed and engine revolutions are at a constant non-zero value for a first predetermined time period; and
detecting a final engine ‘off’ state after a second predetermined time period; and
based on detecting the engine ‘off’ state, changing a level of operation of the device from a running mode to a sleep mode, wherein, in the sleep mode, no power is drawn by the device from the ODB port.
14. The computer readable medium according to claim 13 , wherein the pending engine ‘off’ state is detected from a voltage value that is less than the threshold for a third predetermined time period.
15. The computer readable medium according to claim 13 , wherein the computer readable instructions, when executed, further cause the device to control collection of the OBD data by at least one of: starting the collection of the OBD data when the engine ‘on’ state is detected; and by stopping the collection of the OBD data when the final engine ‘off’ state is detected.
16. The computer readable medium according to claim 13 , wherein the computer readable instructions, when executed, further cause the device to use the determined vehicle engine state to set a start and an end of a trip, so as to determine a trip duration.
17. The computer readable medium according to claim 13 , wherein the computer readable instructions, when executed, further cause the device to, based on detecting the engine ‘on’ state, change a level of operation of the device from a sleep mode to a running mode.
18. A method of detecting a state of a vehicle's engine from vehicle on-board diagnostics (OBD) data using a device having a connector for connecting the device to a vehicle OBD port, the method comprising:
receiving OBD data and power from the vehicle OBD port;
determining a vehicle engine state by monitoring a voltage at the connector, said determining comprising:
(i) detecting an engine ‘on’ state from a temporary voltage drop of at least a predetermined magnitude; and
(ii) detecting an engine ‘off’ state by:
detecting a pending engine ‘off’ state from a voltage value that is less than a threshold;
confirming the pending engine ‘off’ state from the OBD data indicating at least one of vehicle speed and engine revolutions are at a constant non-zero value for a first predetermined time period; and
detecting a final engine ‘off’ state after a second predetermined time period; and
based on detecting the engine ‘off’ state, changing a level of operation of the device from a running mode to a sleep mode, wherein, in the sleep mode, no power is drawn by the device from the ODB port.