Vehicle Powertrain Torque Control Using Inertial Measurement
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Solution Overview
Problem
Conventional torque estimation methods for vehicle transmissions are inaccurate during transient conditions due to changing torque ratios and require prior knowledge of model parameters like vehicle mass, road grade, and tire radius, which can be difficult to determine accurately.
Innovation Solution
A four-parameter mapping method using inertial measurement unit signals and vehicle speed to estimate drive torque, where the mapping parameters are derived based on reference drive torque during non-transient conditions and updated adaptively using recursive least square or Kalman filtering methods, allowing for accurate torque control during transient conditions without requiring precise knowledge of vehicle attributes or drive conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional torque estimation methods using torque ratios are used during transient conditions, then the control system remains simple, but the torque estimation accuracy deteriorates
Solution Approach 1:
The patent transforms the torque estimation problem from using torque ratios (which fail during transients) to using a mapped relationship between inertial forces and vehicle velocity. This parameter transformation enables accurate torque estimation during transient conditions by relying on inertial measurement unit data and velocity measurements rather than torque ratio calculations.
Solution Approach 2:
The patent introduces a mapped relationship as an intermediary between inertial forces and torque control. This mapping, derived during non-transient conditions and stored for use during transients, acts as a mediator that translates inertial measurements into accurate torque estimates without requiring complex real-time calculations during transient events.
2Measurement precision
If prior knowledge of model parameters (vehicle mass, road grade, tire radius) is required for torque estimation, then the estimation can be accurate under steady conditions, but the system becomes difficult to implement and maintain
Solution Approach 1:
The system performs self-calibration by automatically deriving the mapping parameters during non-transient conditions when accurate torque estimation is possible. The controller learns and stores the relationship between inertial forces and velocity without requiring manual input of vehicle specifications, making the system self-configuring and eliminating the need for difficult manual parameter entry.
Solution Approach 2:
The mapping parameters are derived and stored in advance during non-transient conditions before transient events occur. This preliminary action prepares the system with pre-computed relationships that can be quickly applied during transient conditions without requiring real-time calculation or knowledge of vehicle parameters.
3Productivity
If torque control during transient conditions is based on torque ratios, then the control logic remains simple, but the vehicle velocity and propulsion control deteriorate
Solution Approach 1:
The patent implements a dynamic control strategy that automatically switches between two different control approaches based on the operating condition. During non-transient conditions, the system uses torque ratio-based control, while during transient conditions, it switches to the mapped relationship approach using inertial forces and velocity. This dynamic adaptation optimizes propulsion performance across all operating conditions.
Data Source
AI summary
A vehicle includes a transmission, a powerplant, an inertial measurement unit, and a controller. The transmission has an input shaft and an output shaft. The powerplant is configured to generate and deliver torque to the input shaft. The inertial measurement unit is configured to measure inertial forces exerted onto the vehicle. The controller is programmed to, in response to a demanded torque at the output shaft and a non-transient condition of the vehicle, control the torque at the output shaft based on a torque at the input shaft and a gear ratio of the step-ratio transmission. The controller is further programmed to, in response to the demanded torque at the output shaft and a transient condition of the vehicle, control the torque at the output shaft based on the inertial forces and a vehicle velocity.