Robotic Task Sequencing With Demonstration-Guided Primitive Planning
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Solution Overview
Problem
Designing controllers for long-horizon, sequential robotic tasks is challenging due to a large search space and the need for careful reward engineering in reinforcement learning, making it inefficient and data-intensive.
Innovation Solution
The proposed method uses learning from demonstration (LfD) to decompose long demonstrations into meaningful sequences and compose them optimally for novel tasks, employing dynamic movement primitives and graph-search based planning to identify and execute sequences efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If reinforcement learning is used to learn sequences for long-horizon tasks, then the robot can find solutions in the large search space, but it requires enormous amount of data and careful reward engineering
Solution Approach 1:
The patent segments long-horizon tasks into smaller sub-tasks or sequences. Instead of learning entire long sequences at once, the system breaks down complex tasks into manageable chunks that can be learned and reused. This segmentation allows the robot to learn from demonstrations more efficiently without requiring enormous amounts of data, as each segment can be independently learned and then composed to solve novel tasks.
Solution Approach 2:
The patent employs preliminary action by pre-segmenting demonstrated tasks into reusable sequences before encountering novel tasks. The system learns from demonstrations in advance, creating a library of sequences that can be later composed to solve new tasks. This preliminary learning phase reduces the data requirements when facing novel tasks, as the system already has pre-learned sequences to work with.
2Device complexity
If the robot learns full tasks as single motor skills, then the learning process is simplified, but it cannot handle sequential tasks with multiple steps
Solution Approach 1:
The patent applies segmentation by dividing long-horizon tasks into multiple sequences or sub-tasks. Instead of treating each task as a single monolithic skill, the system breaks them down into smaller, reusable sequence segments. This allows the robot to maintain simpler learning models for each segment while still handling complex sequential tasks through composition of these segments.
Solution Approach 2:
The patent introduces dynamics by making the task representation flexible and composable. The system learns sequences that can be dynamically selected and composed based on the specific task requirements. This dynamic composition capability allows the robot to adapt to different sequential tasks using the same set of learned sequences, maintaining simplicity while achieving versatility.
3Manufacturing precision
If reinforcement learning with dense rewards is used for long-horizon tasks, then the robot can learn optimal sequences, but it requires prohibitive amount of data and complex reward engineering
Solution Approach 1:
The patent extracts the reward engineering complexity from the overall system by using demonstration-based learning instead of reinforcement learning. Instead of requiring complex reward functions to guide learning, the system extracts sequences directly from demonstrations, which inherently contain the optimal behavior. This extraction approach achieves sequence optimization without the need for complex reward engineering.
Solution Approach 2:
The patent uses copying by replicating sequences from demonstrations rather than learning them from scratch through reinforcement learning. The system copies successful sequences from demonstrated tasks and reuses them for novel tasks, achieving optimization accuracy without requiring the prohibitive data and complex reward structures that reinforcement learning would demand.
Data Source
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AI summary
A robotic controller is provided for generating sequences of movement primitives for sequential tasks of a robot having a manipulator. The controller includes at least one control processor, and a memory circuitry storing a dictionary including the movement primitives, a pretrained learning module, and a graph-search based planning module having instructions stored thereon. The controller to perform steps acquiring a planned task provided by an interface device operated by a user, wherein the planned task is represented by an initial state and a goal state with respect to an object, generating a planning graph by searching a feasible path of the object for the novel task using the graph-search based planning module and selecting movement primitives from the dictionary in the pretrained learning module, wherein the pretrained learning module has been trained based on demonstration tasks, parameterizing the feasible path represented by the movement primitives as dynamic movement primitives (DMPs) using the initial state and goal state, and implementing the parameterized feasible path as a trajectory according to the selected movement primitives using the manipulator of the robot by tracking and following the parameterized for the planned task.