Task Scheduling for Robot Systems Using Precedence and Residual Time
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Solution Overview
Problem
Real-time systems, such as robot systems, face challenges in efficiently scheduling periodic and aperiodic tasks, especially when using general Operating Systems (OS) like Linux and Windows, as they struggle to maintain real-time execution and precedence relations between tasks, leading to issues like loss of periodic execution and difficulty in controlling component tasks in real-time.
Innovation Solution
A task scheduling method that schedules periodic tasks based on precedence relations and residual time, allowing aperiodic real-time tasks to be executed during leftover time, using a graph structure to prioritize tasks and adjust timer intervals for reliable execution, ensuring both periodic and aperiodic tasks are managed effectively within a robot system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a general OS is applied to the robot system, then ease of operation and recyclability are improved, but real-time execution capability and periodic task reliability deteriorate
Solution Approach 1:
The patent introduces a real-time execution manager as an intermediary layer between the general OS and robot control tasks. This manager component schedules and executes periodic tasks in real-time while utilizing the general OS for non-critical operations, thereby maintaining real-time execution capability while enjoying the ease of operation and recyclability of general OS platforms.
2Adaptability or versatility
If on-line scheduling is used, then flexibility is improved, but ability to handle precedence constraints deteriorates
Solution Approach 1:
The patent performs preliminary offline scheduling to determine execution order and allocate time slots for periodic tasks based on their precedence constraints. This pre-planned schedule is then executed by the real-time execution manager, ensuring that precedence constraints are satisfied while maintaining flexibility for aperiodic task insertion.
3Reliability
If off-line scheduling is used, then periodic task scheduling capability is improved, but ability to schedule aperiodic real-time tasks deteriorates
Solution Approach 1:
The patent implements a dynamic scheduling mechanism where the real-time execution manager continuously monitors system state and adjusts task execution accordingly. Periodic tasks are scheduled offline with fixed time slots, while aperiodic tasks are dynamically inserted into available time slots or preemption points, combining the reliability of offline scheduling with the adaptability needed for aperiodic tasks.
4Adaptability or versatility
If middleware is used to control component tasks, then adaptability and recyclability are improved, but real-time control capability deteriorates
Solution Approach 1:
The patent segments the task control mechanism into two parts: a real-time execution manager that handles time-critical periodic tasks with precise scheduling, and a middleware layer that manages component coordination and data flow. This segmentation allows the system to maintain real-time control capability for critical functions while preserving the adaptability and recyclability benefits of middleware for non-critical operations.
Data Source
AI summary
A task scheduling method and apparatus are provided to execute periodic tasks together with an aperiodic real-time task in a single system, to perform scheduling while satisfying a precedence relation between periodic tasks, and to perform scheduling so that an aperiodic real-time task may be efficiently executed for a residual time left after scheduling of the periodic tasks. Additionally, a component scheduling method and apparatus in robot software are provided.