Vehicle Speed Limit Apparatus Drive Force Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle speed limit systems face challenges in smoothly transitioning from a non-limit state to a limit state due to the inability to correct the vehicle speed limit drive force based on traveling circumstances in the non-limit state, leading to potential exceeding of the limit speed or excessive limitation of drive force, causing discomfort to the driver.
Innovation Solution
A vehicle speed limit apparatus that calculates an upper limit value based on current drive force and corrects it using current and limit accelerations in the non-limit state, ensuring smooth transitions by selecting the smaller value between the demand and upper limit values, and adjusting these values based on current and demand forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the vehicle speed limit drive force is corrected based on the difference between actual acceleration and vehicle speed limit acceleration in the non-limit state, then the probability of actual vehicle speed exceeding limit vehicle speed is reduced, but the vehicle speed limit drive force may exceed appropriate value causing excessive speed or fall below appropriate value causing excessive limitation
Solution Approach 1:
The patent changes the parameter used for correction from acceleration-based (difference between actual and limit acceleration) to force-based (difference between current drive force and vehicle speed limit drive force). This parameter change resolves the contradiction by providing a more reliable correction mechanism that doesn't cause excessive speed or excessive limitation, thereby improving both reliability and driver comfort.
Solution Approach 2:
The patent implements a feedback mechanism where the correction amount is calculated based on the difference between current drive force and vehicle speed limit drive force, and this correction is applied to adjust the vehicle speed limit drive force. This feedback loop ensures that the correction is proportional and appropriate, preventing both excessive speed and excessive limitation, thus resolving the contradiction between reliability and driver comfort.
2Adaptability or versatility
If the drive force is controlled based on driver demand drive force in the non-limit state, then the vehicle speed limit drive force cannot be corrected based on traveling circumstance, but correcting it may cause excessive speed or excessive limitation
Solution Approach 1:
The patent changes the correction parameter from acceleration difference to drive force difference. This allows the system to adapt to traveling circumstances (improving adaptability) while maintaining precise control because the correction is directly based on drive force values rather than acceleration, which can be noisy and imprecise. This resolves the contradiction between adaptability and control precision.
Solution Approach 2:
The patent introduces drive force as an intermediary parameter between the vehicle speed limit drive force calculation and the actual drive force control. By using drive force difference as the correction basis, it mediates between the need to adapt to traveling circumstances and the need for precise control, resolving the contradiction between adaptability and control precision.
3Device complexity
If the vehicle speed limit drive force is calculated based on vehicle speed limit acceleration, then the control is simple, but the smoothness of transition from non-limit state to limit state is reduced
Solution Approach 1:
The patent changes the control parameter from acceleration-based to force-based correction. This maintains relative simplicity in the control system (comparing to complex adaptive algorithms) while significantly improving transition smoothness because the force-based correction provides continuous and gradual adjustment rather than abrupt changes. This resolves the contradiction between device complexity and transition smoothness.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A disclosed vehicle speed limit apparatus (10) includes a demand value calculation part (101) configured to calculate a demand value according to an accelerator opening degree, a limit vehicle speed acquisition part (102) configured to obtain a limit vehicle speed, an upper limit value calculation part (102) configured to calculate an upper limit value based on a limit acceleration, a selection part (103) configured to select the smaller of the demand value and the upper limit value, a control part (104) configured to control a drive force generation apparatus, and an upper limit value correction part (102a) configured to correct the upper limit value based on a current acceleration and the limit acceleration when the selected value corresponds to the upper limit value, and to correct the upper limit value based on the current acceleration and the demand value when the selected value corresponds to the demand value.