Semi-Automatic Gear Shifting Using Topographical Data
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Solution Overview
Problem
Conventional shift control methods for automated multi-step transmissions fail to accurately anticipate topographical changes, leading to delayed or unnecessary gear shifts during transitions between different road gradients and driving resistances, especially in automatic mode, resulting in suboptimal driving dynamics, fuel efficiency, and comfort.
Innovation Solution
The method involves continuous determination of topographical data, specifically the elevation profile, to calculate the driving resistance profile, and deriving specific control commands for overrun downshifts and upshifts based on the maximum continuous braking force curves in relation to the driving resistance profile, allowing for early or blocked shifts to maintain optimal braking power and utilize kinetic energy effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional shift control methods based on current operating parameters are used, then the transmission operates well in most driving situations with good driving dynamics and fuel consumption, but gearshifts are triggered too late or unnecessarily during transitions between different road gradients
Solution Approach 1:
The system performs preliminary actions by determining topographical data for a road section ahead of the motor vehicle and calculating driving resistance profiles in advance. This allows the transmission control to anticipate upcoming gradient changes and trigger gearshifts at optimal times before the actual topographical transition occurs, rather than reacting too late based solely on current operating parameters.
Solution Approach 2:
The system implements feedback by continuously determining topographical data, calculating driving resistance profiles, and using this information to adjust shift control decisions. The control unit compares the calculated driving resistance with actual operating parameters to determine whether to trigger, block, or delay gearshifts, creating a closed-loop control system that improves shifting accuracy.
2Device complexity
If gearshifts are triggered based on current operating parameters without considering future topography, then the control system remains simple, but unnecessary coasting downshifts are triggered when the downhill section changes into a section with lesser gradient
Solution Approach 1:
The system performs preliminary actions by determining topographical data for a road section ahead of the motor vehicle and calculating driving resistance profiles in advance. This allows the transmission control to anticipate upcoming gradient changes and trigger gearshifts at optimal times before the actual topographical transition occurs, rather than reacting too late based solely on current operating parameters.
Solution Approach 2:
The system implements feedback by continuously determining topographical data, calculating driving resistance profiles, and using this information to adjust shift control decisions. The control unit compares the calculated driving resistance with actual operating parameters to determine whether to trigger, block, or delay gearshifts, creating a closed-loop control system that improves shifting accuracy.
3Speed
If overrun upshifts are triggered based on current gradient, then the system responds to immediate conditions, but the momentum of the motor vehicle is insufficient when the gradient end is recognized too late
Solution Approach 1:
The system performs preliminary actions by determining topographical data for a road section ahead of the motor vehicle and calculating driving resistance profiles in advance. This allows the transmission control to anticipate upcoming gradient changes and trigger gearshifts at optimal times before the actual topographical transition occurs, rather than reacting too late based solely on current operating parameters.
Data Source
Figure 1a~1c
Figure 2
AI summary
The invention relates to a method for controlling shifting in a semi-automatic gear transmission that lies in a motor vehicle powertrain, which is provided with a permanent brake, between a drive motor that is designed as an internal combustion engine and an axle drive. Topographical data relating to a road section that lies ahead of the motor vehicle, in particular the height profile, is ascertained during travel together with current vehicle-, road-, and driver-specific operating parameters. The tractive resistance profile (FFW(xF)) of the motor vehicle for the road section that lies ahead is determined from said data and parameters, and control commands for closed-throttle downshifts and/or closed-throttle upshifts are derived and implemented dependent on the tractive resistance profile (FFW(xF)) in the automatic mode of the gear transmission during closed-throttle operation. According to the invention, this is achieved in that the maximum permanent braking force curves (FBr_max(xF)) that are possible in the road section that lies ahead in the currently engaged gear (G0) and in each gear adjacent to said engaged gear are determined based on the current traveling speed (vF(0)), the current engine speed (MMot(0)), and the tractive resistance profile (FFW(xF). The maximum permanent braking force curves (FBr_max(xF)) are analyzed in order to derive control commands for closed-throttle downshift and/or closed-throttle upshift in relation to the tractive resistance profile (FFW(xF)).