Table Tennis Stroke Planning for Spin-Aware Ball Return
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Solution Overview
Problem
Existing table tennis robots struggle to predict and return a ball with precision when the ball is spun, as they do not account for rotational velocity in their decision-making processes.
Innovation Solution
A stroke decision device and method that acquires state information including position, velocity, and rotational velocity of the incoming ball, and computes a stroke condition for the striking implement to accurately return the ball to a target arrival position, adjusting post-strike velocity to minimize error and ensure precise targeting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If simple aerodynamic modeling is used that does not require input of rotational velocity, then the processing load is reduced, but the precision of predicting ball trajectory when the ball is spun deteriorates
Solution Approach 1:
The patent changes the parameter set by explicitly incorporating rotational velocity as an input parameter alongside position and velocity. This allows the aerodynamic modeling to account for spin effects on ball trajectory while maintaining computational efficiency through the structured approach of using defined state information parameters.
Solution Approach 2:
The patent performs preliminary computation of trajectory information based on state information (position, velocity, rotational velocity) before the ball is struck. This pre-computation of predicted trajectory allows the system to plan the stroke in advance, reducing processing load during critical real-time decision-making while maintaining prediction precision.
2Device complexity
If rotational velocity is not taken into consideration, then the decision-making process is simplified, but the precision of returning the ball to target arrival position deteriorates when the ball is applied with spin
Solution Approach 1:
The patent modifies the decision-making parameters by including rotational velocity in the state information that feeds into the stroke decision process. This enables the system to compute appropriate stroke conditions (racket position, velocity, orientation) that compensate for spin effects, thereby maintaining precision without excessive complexity.
Solution Approach 2:
The patent employs a feedback mechanism where the predicted trajectory (computed from state information including rotational velocity) is used to adjust and optimize the stroke condition. The arrival position prediction based on post-strike state information provides feedback that allows the system to refine its stroke decisions, ensuring precise ball return even when spin is involved.
3Measurement precision
If trajectory prediction based on state information including rotational velocity is performed, then the precision of predicting pre-strike and post-strike trajectory is improved, but the processing complexity increases
Solution Approach 1:
The patent performs trajectory prediction computations preliminarily, calculating the predicted trajectory of the incoming ball based on state information (position, velocity, rotational velocity) before the actual strike occurs. This advance computation allows the system to prepare stroke decisions without excessive real-time processing complexity, as the heavy computational work is done in advance.
Solution Approach 2:
The patent segments the trajectory prediction into distinct phases: pre-strike trajectory prediction (based on incoming ball state information) and post-strike trajectory prediction (based on predicted post-strike state information). This segmentation allows each phase to be handled with appropriate computational methods, reducing overall processing complexity while maintaining precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the robot to return the ball to a target arrival position with good precision even when the ball is applied with spin, by considering and adjusting for rotational velocity in its decision-making process.
Implementation Method 1
trajectory prediction section configured to compute trajectory information relating to a predicted trajectory of the incoming ball based on the state information for the ball
Implementation Method 2
when the ball is applied with spin... compute trajectory information relating to a predicted trajectory of the incoming ball based on the state information for the ball
Data Source
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AI summary
A stroke decision device that decides a stroke capable of returning a ball to a target arrival position with good precision even when the ball is applied with spin. A stroke decision device 30 includes an acquisition section 31 configured to acquire state information including a position, a velocity, and a rotational velocity of an incoming ball, and a stroke decision section 32 configured to decide a stroke condition including a position, a velocity, and an orientation of a striking implement at a time point when hitting back the ball toward a target arrival position, based on the state information for the ball and the target arrival position when hitting back the ball with the striking implement.