Autonomous Vehicle Speed Planning With Permeable Constraints

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Solution Overview

Problem

Autonomous driving vehicles face challenges in smooth speed control due to binary constraints, leading to discontinuous driving decisions and potential collisions, especially when dealing with objects that intermittently overlap with the vehicle's path.

Innovation Solution

The implementation of permeable speed constraints, which allow the vehicle to adjust speed based on velocity-dependent obstacles in 'distance vs. time' space, enabling continuous decision-making and reducing sensitivity to binary inputs, thereby allowing the vehicle to pass through constraints smoothly without abrupt braking or acceleration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If binary speed constraints are used to ensure safety by stopping the vehicle when objects are detected, then collision avoidance is improved, but driving smoothness deteriorates due to abrupt braking and discontinuous decisions

Engineering Contradiction:

Improvecollision avoidanceVSAvoiddriving smoothness

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent transforms binary speed constraints (stop/go) into continuous permeable constraints by introducing velocity-dependent parameters. The constraint permeability is calculated based on relative velocity between the vehicle and detected objects, allowing the vehicle to pass through constraints at low speeds while maintaining safety. This resolves the contradiction by enabling smooth, continuous speed adjustments instead of abrupt binary decisions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent makes the speed constraints dynamic and adaptive rather than static and fixed. The permeability of constraints changes dynamically based on real-time velocity conditions, allowing the vehicle to adapt its response to detected objects. This dynamic approach enables continuous, smooth driving behavior while maintaining safety margins, resolving the contradiction between reliability and ease of operation.

Inventive Principle:

Principle #15Dynamics

2Reliability

If strict speed constraints are applied to maintain safety margins from detected objects, then safety is improved, but driving efficiency deteriorates due to unnecessary speed reductions

Engineering Contradiction:

Improvesafety marginVSAvoiddriving efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the parameter of constraint strictness from fixed to variable based on velocity. By introducing velocity-dependent permeability, the system allows stricter constraints at high speeds (maintaining safety) and more permeable constraints at low speeds (improving efficiency). This resolves the contradiction by adapting safety margins to actual driving conditions rather than applying uniform strict constraints.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies partial constraint penetration rather than complete avoidance. The vehicle is allowed to partially violate strict safety margins when moving at low velocities, passing through constraints that would normally be impenetrable. This partial action approach maintains adequate safety while avoiding unnecessary speed reductions, resolving the contradiction between safety and efficiency.

Inventive Principle:

Principle #16Partial or excessive action

3Device complexity

If binary constraint decisions are used to simplify control logic, then system complexity is reduced, but decision continuity deteriorates leading to discontinuous speed profiles

Engineering Contradiction:

Improvecontrol logic simplicityVSAvoiddecision continuity

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The patent introduces velocity as a continuous parameter that modulates constraint permeability, transforming binary decisions into continuous ones. The permeability calculation uses relative velocity to smoothly adjust constraint strictness, eliminating discontinuous jumps in speed profiles. This resolves the contradiction by maintaining relatively simple control logic while achieving continuous, stable decision-making through parameter-based modulation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250002052A1Permeable Speed Constraints

Publication Date: 2025.01.02 WAYMO LLC

AI summary

The technology relates to planning trajectories for self-driving vehicles in order to transport passengers or cargo from a pickup location to a destination. Trajectory planning includes generating a speed plan for an upcoming portion of the trip in view of one or more constraints. The constraints may be due to proximity to an adjacent vehicle or other road user, and can include projected overlaps between the vehicle and other objects in the vehicle's nearby environment. Certain constraints may be binary or otherwise discontinuous in nature, in which a condition either exists at a given point in time or it does not. Noise in sensor data or prediction models may trigger such binary conditions, which in turn may cause the vehicle to alter the speed plan. Aspects of the technology employ permeable speed constraints that enable the vehicle to avoid problems associated with discontinuous constraints.