Parking Assist Acceleration Control for Step-Induced Torque Drops
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Solution Overview
Problem
Existing parking assistance devices experience ride comfort deterioration due to rapid torque decrease when a vehicle goes over a step, caused by a large integrated value of deviation in braking and driving force control.
Innovation Solution
A parking assistance device that includes a target acceleration calculation unit, an acceleration feedback control unit to reset the integrated value of deviation to 0 when the vehicle goes over a step, and a vehicle control unit to manage braking and driving force based on required forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control with integration term is used to reduce disturbance effects, then the ability to handle road surface disturbances is improved, but ride comfort deteriorates when the vehicle goes over a step due to rapid torque decrease
Solution Approach 1:
The control system dynamically adjusts the integrated value based on vehicle state. When a step is detected (through acceleration threshold judgment), the system switches from accumulating integration to resetting it, making the control characteristic adaptive to different road conditions. This resolves the contradiction by making the integration term dynamic rather than static.
Solution Approach 2:
The system changes the parameter of the integrated value from a continuously accumulating value to a reset value when specific conditions are met (step detection). This parameter change allows the system to maintain the benefits of integration for disturbance rejection while avoiding the harmful effects during step transitions.
2Measurement precision
If the integrated value of deviation is maintained to reduce disturbance effects, then control accuracy is improved, but excessive braking force occurs when going over a step causing ride comfort deterioration
Solution Approach 1:
The system takes preliminary action by detecting the step condition through acceleration threshold judgment before excessive braking force can occur. By identifying the step event early, the system can reset the integrated value in advance, preventing the accumulation of deviation that would lead to excessive braking force and subsequent ride comfort deterioration.
Solution Approach 2:
The system uses feedback from acceleration sensors to monitor vehicle state continuously. When the acceleration exceeds a predetermined threshold indicating a step, the feedback loop triggers a reset of the integrated value. This feedback mechanism ensures control accuracy is maintained during normal operation while preventing excessive braking force during step transitions.
Data Source
AI summary
A parking assistance device includes: a target acceleration calculation unit that calculates a target acceleration for moving a vehicle subjected to assistance to a target parking position of the vehicle subjected to assistance; an acceleration feedback control unit that calculates a required braking and driving force based on a deviation between the target acceleration of the vehicle subjected to assistance and an actual acceleration by feedback control including an integration term, determines whether the vehicle subjected to assistance has gone over a step, and resets an integrated value of the deviation between the target acceleration and the actual acceleration to 0 when it is determined that the vehicle subjected to assistance has gone over the step; and a vehicle control unit that controls the braking and driving force of the vehicle subjected to assistance based on the required braking and driving force.