Hierarchical Power Management for Low-Latency Multi-Device AR
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Solution Overview
Problem
Existing power management systems for artificial reality systems, particularly mixed reality headsets, face challenges in managing power efficiently due to their distributed and always-on nature, with implicit triggers and varied computing requirements that complicate centralized power management.
Innovation Solution
Implementing a hierarchical power management system with a parent energy processing unit (EPU) and child EPUs, where the parent EPU manages power decisions across distributed child EPUs, allowing for fine-grained, localized power management of subsystems, including explicit and implicit triggers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If centralized power management is used, then system control is simplified, but power management latency increases and responsiveness to local triggers decreases
Solution Approach 1:
The power management function is segmented into hierarchical levels: a root EPU that manages system-wide power policies and child EPUs that manage local subsystem power states. This segmentation allows centralized coordination while enabling local rapid response to power triggers without waiting for central authorization.
Solution Approach 2:
Child EPUs act as intermediaries between local subsystems and the root EPU. They receive power management decisions from the root EPU but can independently execute power state transitions based on local triggers, serving as buffered intermediaries that reduce latency while maintaining system-wide coherence.
2Loss of energy
If fine-grained localized power management is implemented, then power efficiency improves, but system complexity increases
Solution Approach 1:
The power management architecture is segmented into multiple EPUs at different hierarchical levels, each managing specific power domains. This segmentation enables fine-grained control of individual subsystems while distributing the complexity across multiple manageable units rather than requiring a monolithic complex system.
Solution Approach 2:
Each EPU level manages power according to local characteristics and triggers specific to its domain. The root EPU considers system-wide policies while child EPUs respond to local events, creating locally optimized power management that adapts to specific subsystem requirements without imposing uniform complexity throughout the system.
3Adaptability or versatility
If distributed power management with multiple child EPUs is used, then power management modularity increases, but coordination overhead between EPUs increases
Solution Approach 1:
The power management system is divided into independently functional EPU modules that can be configured and managed separately. Each EPU manages its own power domain with standardized interfaces, enabling modular expansion and reconfiguration without requiring redesign of the entire coordination mechanism.
Solution Approach 2:
EPUs implement universal power management interfaces and standardized communication protocols that allow them to function independently while coordinating through common mechanisms. This universality reduces coordination overhead by providing standardized interaction patterns rather than requiring custom coordination logic for each EPU pair.
Data Source
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AI summary
The disclosure describes artificial reality (AR) systems and techniques that enable hierarchical power management of multiple devices within a multi-device AR system. For example, a multi-device AR system includes a device comprising one of a peripheral device configured to generate artificial reality content for display or a head-mounted display unit (HMD) configured to output artificial reality content. The device comprises a System on a Chip (SoC) that includes a host subsystem and plurality of subsystems. Each subsystem includes a child energy processing unit configured to manage power states for the subsystem. The host subsystem includes a parent energy processing unit configured to direct power management of each of the child energy processing units of the plurality of subsystems.