Robot Joint Trajectory Planning for Dynamic Target Tracking Lag

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Solution Overview

Problem

Existing motion planning methods for robots face challenges in tracking dynamic targets due to delays in visual feedback frequency, leading to significant lag errors in online planning trajectories.

Innovation Solution

A dynamic target tracking method that predicts the motion of a target in real-time, compensates for lag in space, and performs online trajectory optimization using model prediction to reduce lag and ensure smooth motion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If online trajectory planning is used to track dynamic targets, then the robot can react to changes in the environment and moving targets, but significant lag error occurs due to delay in visual feedback frequency

Engineering Contradiction:
Improvereaction to environment changesVSAvoidtrajectory accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system performs motion prediction in advance to forecast the dynamic target's future position based on current motion state. This preliminary action compensates for the inherent delay in visual feedback, allowing the robot to plan trajectories toward predicted rather than historical target positions, thereby reducing lag error while maintaining adaptability to environmental changes

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If visual feedback frequency is increased to reduce lag error, then trajectory accuracy improves, but system complexity and computational burden increase

Engineering Contradiction:
Improvetrajectory accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system introduces a motion prediction module as an intermediary between visual feedback acquisition and trajectory planning. This mediator processes the low-frequency visual feedback to generate predicted target positions, effectively decoupling the trajectory accuracy from the visual feedback frequency. The intermediary transforms limited feedback data into accurate predictive information without requiring increased feedback frequency or system complexity

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If online trajectory planning is performed in real-time, then the robot can adapt to moving targets, but computational resources are insufficient for sufficiently fast solutions

Engineering Contradiction:
Improveonline adaptation capabilityVSAvoidcomputational speed
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The motion prediction module performs preliminary computation to forecast target positions before actual trajectory planning begins. By pre-calculating where the target will be rather than reacting to where it was, the system reduces the complexity and time required for real-time trajectory optimization, enabling faster computational responses while maintaining online adaptation capability

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the temporal parameter of target position from historical feedback values to predicted future values. This parameter transformation allows trajectory planning to work with anticipatory data rather than delayed data, reducing the computational burden of correcting large lag errors while maintaining real-time adaptability to moving targets

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS12420413B2Dynamic target tracking method, robot and computer-readable storage medium
Publication Date: 2025.09.23 UBTECH ROBOTICS CORP LTD
  • US12420413B2 patent drawing
  • US12420413B2 patent drawing
  • US12420413B2 patent drawing

AI summary

A dynamic target tracking method for a robot having multiple joints includes: obtaining a motion state of a tracked dynamic target in real time; performing motion prediction according to the motion state at a current moment to obtain a predicted position of the dynamic target; performing lag compensation on the predicted position to obtain a compensated predicted position; performing on-line trajectory planning according to the compensated predicted position to obtain planning quantities of multi-step joint motion states at multiple future moments, and determining a multi-step optimization trajectory according to the planning quantities and a multi-step optimization objective function; and controlling the joints of the robot to according to the multi-step optimization trajectory.