Sensor Data Processing Device Timestamp Synchronization

Solution Overview

Problem

Existing sensor systems face inaccuracies in converting sensor hub time stamps to host processor time stamps due to interrupt response latency and the infrequent nature of interrupts, leading to degraded accuracy of clock factor and offset calculations.

Innovation Solution

A sensor-data processing device that includes interfaces for communication with sensor elements and computer devices, generates its own time base, and assigns time stamps, allowing for the transmission of request signals to acquire synchronized time stamps for determining conversion parameters, such as offset and clock ratio, thereby enabling accurate and reliable conversion of time stamps between the sensor device and computer device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If interrupt-based time stamp comparison is used, then the system can operate with simple hardware, but the measurement precision of time stamps is degraded due to interrupt response latency

Engineering Contradiction:

Improvehardware complexityVSAvoidtime stamp accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

A dedicated time stamp counter unit is introduced as an intermediary hardware component that independently captures time stamps without being affected by interrupt response latency. This mediator unit runs parallel to the main processor and provides accurate time stamp measurements solely through hardware operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The software-based interrupt handling mechanism is replaced with a hardware-based time stamp counter. This substitution eliminates the dependency on software interrupt response time, providing continuous and accurate time stamp measurements independent of processor workload and interrupt priority handling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If interrupt-based time stamp acquisition is used, then the system structure remains simple, but the reliability of time stamp conversion is degraded due to long intervals between interrupts

Engineering Contradiction:

Improvesystem structureVSAvoidtime stamp conversion reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The time stamp counter operates continuously without interruption, continuously incrementing and capturing time values. This continuous operation ensures that time stamps are always available and accurately reflect the current time, eliminating gaps that occur with interrupt-based periodic sampling.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The time stamp counter is a self-sufficient hardware unit that autonomously generates and maintains accurate time stamp values without requiring external triggering or software intervention. It independently performs its time measurement function, ensuring reliable operation regardless of system state or interrupt frequency.

Inventive Principle:

Principle #25Self-service

3Device complexity

If software-based interrupt time stamp measurement is used, then hardware requirements remain minimal, but the measurement precision is reduced due to undefined temporal offsets from interrupt response latency

Engineering Contradiction:

Improvehardware requirementsVSAvoidtime stamp measurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

A dedicated time stamp counter unit is introduced as an intermediary hardware component that independently captures time stamps without being affected by interrupt response latency. This mediator unit runs parallel to the main processor and provides accurate time stamp measurements solely through hardware operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The software-based interrupt handling mechanism is replaced with a hardware-based time stamp counter. This substitution eliminates the dependency on software interrupt response time, providing continuous and accurate time stamp measurements independent of processor workload and interrupt priority handling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11493948B2Sensor-data processing device

Publication Date: 2022.11.08 ROBERT BOSCH GMBH

AI summary

A sensor-data processing device, including at least one interface to communicate with at least one sensor element for detecting sensor events; at least one interface to communicate with at least one external computer device for processing sensor data representing the sensor events; devices for generating at least one time base specific to the sensor-data processing device; a device for assigning time stamps to the sensor events, the time stamps being based on the time base of the sensor-data processing device and being specific to the sensor-data processing device; a device for receiving a request signal from the computer device; with the aid of the computer device, the request signal being able to be assigned a time stamp based on a time base specific to the computer device; and a device for assigning a time stamp specific to the sensor-data processing device, to the request signal.