Self-Driving Vehicle Mass Determination via Triggered Force Phases
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Solution Overview
Problem
Existing methods for estimating the vehicle mass of self-driving vehicles are prone to inaccuracies due to various non-observed influencing factors, leading to unreliable mass determination, especially in dynamic driving conditions.
Innovation Solution
A procedure involving a central control unit that alternates between two phases to apply different force values to determine vehicle mass, utilizing sensor data to distinguish between internal and disruptive forces, thereby minimizing processing effort and ensuring precise mass estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous mass determination is performed to ensure accurate vehicle mass, then measurement precision is improved, but processing effort and system complexity increase
Solution Approach 1:
The system performs mass determination periodically based on trigger events rather than continuously. The control unit activates the mass determination procedure only when specific conditions are met (trigger events), such as when the vehicle is stationary or during specific driving phases, thereby reducing processing effort while maintaining measurement accuracy when needed.
Solution Approach 2:
The system prepares for mass determination by detecting trigger events in advance and activating the determination procedure only when conditions are favorable. This preliminary detection allows the system to perform mass determination at optimal moments without requiring continuous processing, reducing overall system complexity.
2Ease of operation
If traditional mass estimation methods are used based on Newton's second law, then ease of operation is improved, but measurement precision deteriorates due to unobserved influencing factors
Solution Approach 1:
The system extracts and separately determines disturbance forces acting on the vehicle from the total measured forces. By isolating disturbance forces (such as aerodynamic drag, rolling resistance, and gradient forces) from the internal forces, the system can calculate vehicle mass more accurately using Newton's second law without the contaminating effect of unobserved influencing factors.
Solution Approach 2:
The system introduces disturbance force determination as an intermediary step between force measurement and mass calculation. By first determining disturbance forces and then subtracting them from total forces before applying Newton's second law, the system achieves more accurate mass estimation while maintaining operational simplicity.
3Productivity
If mass determination is performed during normal driving operation, then productivity is improved, but measurement precision deteriorates due to disturbance forces
Solution Approach 1:
The system dynamically adapts the mass determination procedure based on vehicle operating conditions. It uses multiple phases (first phase with active drive/brake, second phase with released drive/brake) to characterize disturbance forces under actual driving conditions, allowing accurate mass determination during normal operation by compensating for disturbance forces in real-time.
Solution Approach 2:
The system uses feedback from acceleration measurements and force data to continuously characterize disturbance forces and refine mass determination. By comparing expected acceleration from applied forces with actual measured acceleration, the system can identify and compensate for disturbance forces, maintaining measurement precision during productive normal operation.
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
This approach allows for precise and efficient vehicle mass determination, enhancing the predictability of the target trajectory and stability in self-driving vehicles, even under unstable conditions, without constant validation or interference with normal operation.
Implementation Method 1
The vehicle mass is traditionally estimated according to Newton's second law (F = M x A) while driving. The internal force (F), a driving force or a braking force, for example, is derived from engine torque, taking into account other vehicle parameters (e.g., the number of vehicle axles) as well as losses in the drive train or brake management, and the vehicle acceleration (A) is derived from the wheel speed of the wheels.
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a method for determining the mass (M) of a self-driving vehicle (1), in which an internal force (F) can be exerted on the self-driving vehicle (1) by an automated control of an electronic drive system (3) and/or of an electronic braking system (2), said method comprising at least the following steps: - ascertaining whether a trigger event is occurring, which specifies that a change in the vehicle mass (M) is probable, and - activating a teaching mode of operation when a trigger event is occurring, in which the self-driving vehicle (1) is operated alternately in a first and a second phase, and in which by automatic control of the electronic drive system (3) and/or of the electronic braking system (2) -- in the first phase an internal force (F) having a first force value is exerted on the self-driving vehicle (1), and -- in the second phase an internal force (F) having a second force value is exerted on the self-driving vehicle (1), the first force value differing from the second force value; - determining a disruptive force acting in the phases; and - determining the vehicle mass (M) depending on the vehicle acceleration (A) and the internal force (F) occurring in the particular phase, and depending on the determined disruptive force.