Wheel Load Estimation Using Inertia Tensor and CG Shift
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wheel load estimation techniques for vehicles with heavy loads, such as forklifts, fail to accurately estimate wheel loads without reducing the rigidity of the vehicle body, and some methods pose safety risks by requiring reduced rigidity.
Innovation Solution
A wheel load estimation device and program that calculates wheel loads using angular velocities, accelerations, and center-of-gravity information, including inertial principal axes, to estimate wheel loads without reducing the vehicle's rigidity, by considering fluctuations in the center of gravity and incorporating yaw moments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rigidity of the portion on which the loading object is loaded is decreased to measure strain, then wheel load measurement becomes possible, but safety risk increases
Solution Approach 1:
The patent introduces an intermediary approach by using the vehicle body's rigid structure and inertial properties as a mediator to indirectly measure wheel loads. Instead of directly measuring strain on the loading portion, the system uses accelerometers on the rigid vehicle body to capture motion data, which is then processed through inertial parameter calculations to derive wheel load information, thus avoiding the need to compromise structural rigidity
Solution Approach 2:
The patent replaces the mechanical strain measurement system with an inertial-based measurement system. Instead of using strain gauges on the loading portion that require reduced rigidity, the system substitutes a rigid vehicle body with accelerometers that measure angular velocities and linear accelerations, which are then used to calculate wheel loads through inertial parameter relationships
2Measurement precision
If general four-wheel vehicle estimation techniques are used, then wheel load estimation is possible, but accuracy deteriorates when heavy loading objects are loaded in various states
Solution Approach 1:
The patent applies dynamics by making the inertial parameters dynamic rather than static. The moment of inertia values and inertial principal axis orientations are calculated based on the actual loading state, allowing the estimation system to adapt to varying heavy load conditions. This dynamic adjustment of inertial parameters enables accurate wheel load estimation across different loading configurations
Solution Approach 2:
The patent changes the parameters used in wheel load estimation from fixed general vehicle parameters to dynamic parameters that reflect the actual loading state. By calculating moment of inertia values and inertial principal axis orientations based on current loading conditions, the system adjusts its estimation parameters to maintain accuracy under varying heavy load states
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
Accurately estimates wheel loads in vehicles with fluctuating centers of gravity without reducing rigidity, ensuring safety and precision in load estimation.
Implementation Method 1
an inertial measurement unit measuring angular velocities and linear accelerations
Implementation Method 2
a weighing unit measuring a weight of the loading object
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
According to the present invention, a center-of-gravity inertia value calculation unit (36, 236) calculates information about the center of gravity of a vehicle including a load, calculates an inertia tensor (Jall) including the inertial spindle around the center of gravity of the vehicle and the inertial product, and a wheel load variation calculation unit (40, 240) calculates the variation amount of a wheel load, on the basis of the inertia tensor (Jall), angular velocities (P, Q, R) around three axes of the vehicle including the load, angular acceleration (P, Q, R), front-rear and lateral accelerations of the vehicle (Gxall, Gyall), a vehicle weight (Mall) including the load, and information about the center of gravity of the vehicle including the load (hR_CG, hcc, tl, tr, lf, lr), and a wheel load estimation unit (42, 242) estimates the wheel load, on the basis of the variation amount and the static load of the wheel load.