Vehicle Speed Control Adapting to Road Grade and Traffic Density
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Solution Overview
Problem
Existing vehicle speed control systems face challenges in optimizing energy efficiency without advance knowledge of road grade variations and in minimizing their impact on surrounding traffic flow, especially in varying traffic conditions.
Innovation Solution
A speed control system that adjusts vehicle speed based on a control policy, using a road grade estimator and traffic density estimator to generate periodic speed adjustments, adopting a constant speed in heavy traffic and varying speed offsets in lighter conditions to minimize disruption to traffic flow and optimize fuel economy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If variable speed offsets are applied to optimize fuel economy, then energy efficiency is improved, but impact on surrounding traffic flow increases
Solution Approach 1:
The system dynamically changes the speed offset parameter based on traffic density conditions. When traffic density is low, larger speed offsets are applied to optimize fuel economy. When traffic density increases, the speed offsets are reduced or eliminated to minimize disruption to traffic flow. This parameter adaptation resolves the contradiction by adjusting the degree of speed variation according to environmental conditions.
Solution Approach 2:
The speed control system transitions from static constant-speed cruise control to dynamic variable-speed control that adapts to real-time traffic conditions. The controller continuously monitors traffic density and adjusts the speed profile accordingly, enabling the system to optimize fuel economy when conditions permit while maintaining traffic compatibility when conditions require it.
2Use of energy by moving object
If aggressive speed fluctuations are used to maximize efficiency improvement, then fuel consumption is reduced, but traffic flow disruption increases
Solution Approach 1:
The system modifies the amplitude of speed fluctuations based on traffic density parameters. In light traffic conditions, aggressive speed variations are permitted to maximize fuel savings. In heavy traffic conditions, the system reduces fluctuation amplitude to maintain traffic flow continuity. This dynamic parameter adjustment resolves the contradiction between efficiency gain and productivity maintenance.
3Stability of the object's composition
If constant speed control is used in heavy traffic, then traffic flow stability is maintained, but fuel economy optimization is lost
Solution Approach 1:
The system dynamically switches between constant-speed mode and variable-speed mode based on traffic density. In heavy traffic conditions, constant speed control maintains stability. In lighter traffic conditions, variable speed offsets enable fuel economy optimization. This dynamic mode switching resolves the contradiction by selecting the appropriate control strategy for current conditions.
Solution Approach 2:
The controller periodically evaluates traffic density conditions and adjusts the speed control strategy accordingly. This periodic assessment enables the system to transition between constant-speed and variable-speed modes, capturing fuel economy opportunities when traffic conditions permit while maintaining stability when conditions require it.
Data Source
AI summary
Vehicle apparatus includes a speed control for adjusting a vehicle powertrain of the vehicle in response to a speed setpoint. A grade estimator determines a road grade of a roadway where the vehicle is traveling. A traffic density estimator determines a density of traffic traveling on the roadway in the vicinity of the vehicle. An optimizer executes a selected control policy to periodically generate speed adjustments for applying to the speed setpoint to operate the vehicle powertrain at increased efficiency. The control policy is based on a value function providing an optimized solution for a cost model responsive to the determined road grade to generate an initial speed offset. The optimizer reduces the initial speed offset in proportion to the determined traffic density to generate the speed adjustments. The system minimizes negative impacts to overall traffic flow as well as any negative contribution to reduced fuel efficiency of surrounding traffic.