Multi-Chip Camera Control for Low-Latency Synchronized VCM Outputs
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Solution Overview
Problem
Existing camera control systems face challenges in efficiently extending voice coil motor (VCM) driver outputs beyond the capabilities of a single device while maintaining tight synchronization and minimizing latency.
Innovation Solution
A system and method involving a primary and secondary camera controller device connected by a communication link, where the primary device processes sensor data and generates control data, which is mirrored by the secondary device to achieve synchronized VCM driver outputs, using a Universal Asynchronous Receiver/Transmitter (UART) and Event Timer to ensure tight synchronization and minimize latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single camera controller device is used, then device complexity is reduced, but the capability to extend VCM driver outputs beyond single-device limits is restricted
Solution Approach 1:
The system divides the camera controller functionality into multiple independent devices (primary CCD and secondary CCD), where each device can independently sense position sensors and generate control data. This segmentation allows the system to extend VCM driver outputs beyond single-device capabilities while maintaining manageable complexity at each device level.
Solution Approach 2:
Multiple camera controller devices are merged into a coordinated system through inter-chip communication, combining their individual VCM driver outputs into a unified controlled system. The primary and secondary devices work together as a single logical unit, achieving extended output capability while distributing the computational load.
2Adaptability or versatility
If multiple camera controller devices are used to extend VCM driver outputs, then output capability is improved, but synchronization between devices becomes more difficult
Solution Approach 1:
The system implements feedback mechanisms where each camera controller device independently senses position sensors and provides this information to the other device through inter-chip communication. This feedback loop ensures that both devices have access to the same position information, enabling them to generate synchronized control data despite operating as separate physical devices.
Solution Approach 2:
Position sensor information is sensed and prepared in advance by each device before being exchanged through the communication link. This preliminary action ensures that when control data is generated, both devices have the necessary synchronized information ready, reducing latency and improving synchronization accuracy.
3Adaptability or versatility
If position sensor information is exchanged between devices, then remote sensing capability is improved, but communication latency increases
Solution Approach 1:
Each camera controller device independently senses position sensors and prepares position information in advance before exchange is needed. This preliminary sensing and preparation eliminates waiting time during the actual control cycle, reducing the effective latency of inter-chip communication while enabling remote sensing capability.
Solution Approach 2:
The system maintains continuous sensing of position sensors by both devices, ensuring that position information is always available and up-to-date. This continuous action eliminates gaps in data availability, allowing immediate use of position information for control data generation without additional latency.
4Productivity
If demand for position sensor information is prepared at offset from control loop period start, then secondary position sensor information is received within current control loop period, but timing precision requirements increase
Solution Approach 1:
The demand for position sensor information is prepared at a predetermined time offset before the control loop period begins. This preliminary preparation ensures that the information exchange and processing are completed within the current control loop period, improving overall control loop efficiency while the offset timing is precisely managed.
Solution Approach 2:
Each camera controller device independently manages its own timing and processing of position sensor information, with the primary device preparing demands at calculated offsets. This self-service approach allows each device to optimize its internal timing without requiring complex external synchronization, reducing the burden of timing precision requirements.
Data Source
AI summary
A system that controls a lens/image sensor position includes primary and secondary camera control devices (CCDs) and a communication link connecting them. The CCDs periodically sense respective primary and secondary position sensors to obtain respective primary and secondary position samples. The primary prepares a demand for secondary position sensor information and transmits the demand to the secondary. The secondary produces the secondary position sensor information by decimating secondary position samples that are youngest with respect to the demand and transmits the secondary position sensor information to the primary. The primary produces primary position sensor information by decimating primary position samples and generates control data by processing the primary and secondary position sensor information. The primary prepares the demand at a predetermined time offset from a start of a current control loop period such that the secondary position sensor information is received by the primary within the current control loop period.