Trajectory Generation for Humanoid Robots

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing trajectory generation systems for humanoid robots can result in discrete temporal differentiation values, such as velocity or acceleration, when the specified time for foot contact with the ground is varied, leading to non-smooth trajectories.

Innovation Solution

A trajectory generation system comprising a first element that sets variable times and a second element that generates a function over a specified period, ensuring the integral value of the third-order temporal differentiation function is minimal, maintaining smoothness of first and second-order temporal differentiation functions while allowing time variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the specified time for foot contact is varied to adapt to different walking conditions, then the adaptability of the trajectory generation system is improved, but the smoothness of temporal differentiation functions (velocity, acceleration trajectories) deteriorates and becomes discrete

Engineering Contradiction:

Improveadaptability of trajectory generation systemVSAvoidsmoothness of temporal differentiation function

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent changes the parameter being optimized from the traditional approach (matching position at specified time) to minimizing the integral of the absolute value of the third-order temporal differentiation function. This parameter change allows the system to maintain smoothness in velocity and acceleration trajectories even when the specified time for foot contact is varied, thereby resolving the contradiction between adaptability and smoothness.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the trajectory is generated to match the desired value at the specified time using a dead beat filter, then the positioning accuracy is improved, but the temporal differentiation trajectories become discrete when specified time varies

Engineering Contradiction:

Improvepositioning accuracyVSAvoidsmoothness of velocity and acceleration trajectories

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent changes the optimization parameter from position matching (dead beat filter approach) to minimizing the integral of the third-order temporal differentiation. This allows the system to achieve both positioning accuracy and smooth velocity/acceleration trajectories simultaneously, even when the specified time varies.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a dynamic optimization approach where the trajectory is generated by minimizing the integral of the absolute value of the third-order temporal differentiation function over the specified period. This dynamic approach adapts to varying specified times while maintaining smoothness in the temporal differentiation functions, unlike static dead beat filters that produce discrete trajectories when time varies.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8903880B2Trajectory generation system and trajectory generation method

Publication Date: 2014.12.02 HONDA MOTOR CO LTD

AI summary

A specified function p is generated to satisfy a first condition that an integral value of an evaluation function over a specified period is minimal. The evaluation function denotes a magnitude of an absolute value of a third order specified function p(3)(t). Moreover, the specified function p is generated to satisfy a second condition that a value of a second order specified function p(2)(t) is limited within a limiter range [p(2)min_c, p(2)max_c].