Assist Force Control for Low-Speed Mobile Objects
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Solution Overview
Problem
Existing mobile object control devices face challenges in providing a smooth assist motion due to noise and calculation errors when controlling assist forces based on calculated mass, leading to inefficient assistance during low-speed movements.
Innovation Solution
A mobile object control device that calculates assist forces using rolling resistance, power loss, and drive force parameters, with optional features like tilt angle detection and correction, assist force control, and current control, to minimize calculation errors and enhance assist motion smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If assist force is controlled based on calculated mass, then the control system can provide mass-dependent assistance, but calculation errors and noise prevent smooth assist motion
Solution Approach 1:
The patent extracts the mass calculation from the assist force control by removing the dependency on calculated mass. Instead of using mass (which introduces calculation errors), the system directly uses acceleration, rolling resistance, and power loss measurements to calculate assist force, thereby eliminating the source of instability while maintaining automatic control
Solution Approach 2:
The patent replaces the mass-based control mechanism with a force-based control mechanism. Instead of calculating mass from acceleration and then deriving assist force, the system directly measures acceleration and combines it with rolling resistance and power loss calculations to determine assist force, substituting an indirect calculation path with a more direct and reliable measurement approach
2Adaptability or versatility
If mass calculation is used to determine assist force, then the system can adapt to different loads, but noise and calculation errors degrade measurement precision
Solution Approach 1:
The patent implements feedback by continuously monitoring acceleration and using it to adjust assist force calculations in real-time. The system measures actual acceleration, calculates the required assist force based on this measurement plus rolling resistance and power loss, and adjusts motor output accordingly, creating a closed-loop control that adapts to varying loads while maintaining precision
Solution Approach 2:
The patent changes the parameters used for assist force calculation from mass-dependent parameters to acceleration-dependent parameters. By using acceleration (which can be measured directly and reliably) instead of mass (which requires calculation and introduces errors), the system maintains adaptability to different loads while improving measurement precision through more reliable input parameters
Data Source
AI summary
A mobile object control device controls an electric motor assisting traveling of a mobile object. The mobile object control device includes a rolling resistance calculation section, a power loss calculation section, and an assist force calculation section. The rolling resistance calculation section calculates a rolling resistance based on a set weight set by a user. The power loss calculation section calculates a power loss caused until a power outputted from the electric motor is transmitted to a drive wheel. The assist force calculation section calculates an assist force of the electric motor based on an acceleration of the mobile object, the set weight, the rolling resistance calculated by the rolling resistance calculation section, the power loss calculated by the power loss calculation section, and an assist ratio.