Vehicle Mass Estimator Circuit Using Motor Current in Real Time
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Solution Overview
Problem
Electric vehicles often operate in environments where payload changes frequently, making it difficult to determine the vehicle's weight in real-time, especially since weigh stations are not always accessible, leading to delays and increased costs.
Innovation Solution
A vehicle mass estimator circuit that calculates the vehicle's mass using motor current, motor angular velocity, and acceleration information, allowing for real-time mass estimation without the need for a scale or dedicated mass sensing system, and can operate in two modes: one with and one without an accelerometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a scale or dedicated mass sensing system is used to measure vehicle mass, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical mass sensing systems (scales, dedicated mass sensors) with an electrical estimation system that uses motor current measurements and vehicle dynamics models to calculate mass. The controller estimates mass by processing electrical signals from the motor controller and applying physics-based calculations, eliminating the need for physical contact with scales or dedicated mass sensing hardware.
Solution Approach 2:
The patent introduces motor current as an intermediary parameter to indirectly measure vehicle mass. Instead of directly measuring mass, the system measures motor current and uses it as a mediator to estimate mass through calculations involving vehicle acceleration, motor torque, and rotational dynamics. This intermediary approach allows mass estimation without direct mass sensing.
2Measurement precision
If the vehicle stops at a weigh station to determine weight, then measurement precision is improved, but loss of time and productivity increase
Solution Approach 1:
The patent performs mass estimation continuously during normal vehicle operation rather than requiring a separate weighing action. The system preliminarily estimates mass using data already collected during vehicle operation (motor current, acceleration, velocity), eliminating the need to stop at weigh stations. The mass information is available in real-time as part of the normal control operations.
Solution Approach 2:
The patent maintains continuous mass estimation throughout vehicle operation, transforming a discrete stopping action into a continuous process. The controller continuously processes motor current and vehicle dynamics data to update mass estimates, ensuring mass information is always available without interrupting delivery operations. This continuous estimation integrates seamlessly with ongoing vehicle operation.
3Device complexity
If motor current and vehicle dynamics data are processed to estimate mass, then device complexity is reduced, but measurement precision may worsen without dedicated sensors
Solution Approach 1:
The patent implements feedback mechanisms where the estimated mass is continuously refined using ongoing measurements of motor current, vehicle acceleration, and velocity. The system compares estimated mass with expected mass ranges and adjusts estimation parameters accordingly. This feedback loop compensates for the lack of dedicated mass sensors by continuously validating and refining the mass estimate against multiple independent measurements.
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
Enables real-time reporting of vehicle mass, reducing costs and improving operational efficiency by providing accurate mass information during vehicle operation, even in scenarios where traditional weighing is not feasible.
Implementation Method 1
a motor that is mechanically coupled to wheels of the vehicle
Implementation Method 2
A vehicle includes a vehicle mass estimator circuit. The vehicle mass estimator circuit accesses the rotor inertia information determined for the vehicle chassis type
Data Source
AI summary
A vehicle includes a vehicle mass estimator circuit. The vehicle mass estimator circuit is configurable to estimate a mass of vehicle during real-time operation of the vehicle without employing a scale or dedicated mass sensing system. The vehicle mass estimator circuit generates the vehicle mass Mv from: (1) an estimated torque or sensed torque, (2) an estimated motor angular velocity or sensed motor angular velocity, and (3) sensed acceleration or without any sensed acceleration. In one embodiment, the vehicle mass estimator circuit senses motor current during vehicle operation and estimates a mass of the vehicle using the motor current without any dedicated acceleration sensor such as an accelerometer. A motor angular velocity is estimated from the motor current. In another embodiment, the vehicle mass estimator circuit senses motor current during vehicle operation and estimates a mass of the vehicle using the motor current and acceleration information provided by an accelerometer.