Hardware-based time synchronization for heterogeneous sensors in autonomous vehicles

A system for synchronization in a vehicle, comprising:

• a plurality of sensors configured to provide sensing capabilities for vehicle navigation;
• a first navigation unit;
• a first synchronization unit, coupled to the plurality of sensors and the first navigation unit and configured to:
• generate, based on a nominal pulse-per-second (PPS) signal, a plurality of output trigger pulses configured to synchronize operations of a plurality of sensors, each of the plurality of output trigger pulses having a frequency equal to an operating frequency of a corresponding sensor of the plurality of sensors, and
• transmit the plurality of output trigger pulses to the plurality of sensors, wherein a triggered frequency of at least one of the plurality of sensors is compared with a frequency provided by a synchronization module in the vehicle to detect abnormalities,
• wherein, when the first navigation system functions correctly, the nominal PPS signal is provided by the first navigation unit, and
• wherein, when the first navigation unit does not function correctly, the nominal PPS signal is generated by a simulated clock source of the first synchronization unit;
• a second navigation unit;
• a second synchronization unit, coupled to the second navigation unit and configured to perform functions of the first synchronization unit when an error signal is received from the first synchronization unit,
• wherein the first synchronization unit and the second synchronization unit are further configured to:
• receive a timing signal comprising a timestamp corresponding to an absolute time, and
• perform a periodic exchange of heartbeat messages, wherein an interruption of the periodic exchange is indicative of a failure of the first synchronization unit or the second synchronization unit, and, in an event of a failure of the first synchronization unit or the second synchronization unit, the functional synchronization unit is configured to propagate the plurality of output trigger pulses,
• wherein the first synchronization unit, coupled to the second navigation unit, is further configured to transmit the timestamp to the plurality of sensors, and
• wherein at least one of the first synchronization unit or the second synchronization unit is further configured to:
• align a first timestamp from the first navigation unit and a second timestamp from the second navigation unit.

A device for synchronization in a vehicle, comprising:

• a processor configured to:
• generate, based on a nominal pulse-per-second (PPS) signal, a plurality of output trigger pulses configured to synchronize operations of a plurality of sensors, each of the plurality of output trigger pulses having a frequency equal to an operating frequency of a corresponding sensor of the plurality of sensors;
• and
• transmit the plurality of output trigger pulses to the plurality of sensors,
• wherein a triggered frequency of at least one of the plurality of sensors is compared with a frequency provided by a synchronization module in the vehicle to detect abnormalities,
• wherein, a rising edge of at least one of the plurality of output trigger pulses resets at least one parameter of a sensor of the plurality of sensors, wherein, when a navigation unit in the vehicle functions correctly, the nominal PPS signal is provided by the navigation unit, and
• wherein, when the navigation unit does not function correctly, the nominal PPS signal is generated by a simulated clock source of the synchronization unit.