| CPC F16H 61/0437 (2013.01) [G06N 20/00 (2019.01); F16H 2061/0459 (2013.01)] | 2 Claims |
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1. A gearshift overlap control system for improving vehicle dynamic response, wherein the control system performs a gearshift overlap control based on iterative learning, wherein the control system comprising:
a gearshift progress calculation module: the gearshift progress calculation module is capable of calculating a gearshift progress in real time;
a clutch control module: the clutch control module is capable of executing a first power-on downshift control and starting to control a second power-on downshift clutch when the gearshift progress reaches a preset gearshift progress at which a second power-on downshift is requested;
an iterative learning control module: the iterative learning control module is capable of automatically adjusting a first on-coming clutch control pressure and a first off-going clutch control pressure in a first power-on downshift by means of monitoring an overshoot of the gearshift progress, thereby reducing the overshoot of the gearshift progress, wherein in the gearshift progress calculation module, a calculation method of the gearshift progress is as follows:
 wherein η represents the gearshift progress, ic represents a speed ratio of a current gear, it represents a speed ratio of a target gear, and i represents a ratio of a rotation speed of an input shaft to a rotation speed of an output shaft of a transmission, wherein a calculation formula is as follows:
 wherein ω1 represents the transmission input shaft rotation speed, and ω2 represents the transmission output shaft rotation speed, wherein based on the gearshift progress, defining a gearshift overlap factor γ:
 wherein ηs represents a corresponding gearshift progress when the second power-on downshift is requested, wherein in the clutch control module, after the first power-on downshift is completed, the second power-on downshift is controlled based on the corresponding gearshift progress ηs when the second power-on downshift is triggered, wherein the first power-on downshift process further comprises:
a first filling phase, a first inertia phase and a first torque phase,
wherein the second power-on downshift process further comprises:
a second filling phase, a second inertia phase and a second torque phase, wherein in the first filling phase, the clutch control module controls the first off-going clutch control pressure to reduce to a minimum oil pressure at which a first off-going clutch does not slip, and the clutch control module controls the first on-coming clutch control pressure to reach a first on-coming clutch KP point, wherein the KP point represents a critical point oil pressure that the clutches are engaged but do not transmit torque, wherein in the first inertia phase, the gearshift progress starts to increase from 0, wherein when the gearshift progress does not reach ηs, the clutch control module controls the first off-going clutch based on a feedforward controller and a feedback controller calibrated in a single power-on downshift, and the clutch control module maintains the first on-coming clutch control pressure at a first on-coming clutch KP point oil pressure, wherein when the gearshift progress reaches ηs, the second inertia phase is triggered, resulting in a failure of the feedback controller based on the rotation speed of the input shaft, wherein subsequently, the clutch control module controls the first off-going clutch based on the feedforward controller calibrated in a single power-on downshift, and the clutch control module maintains the first on-coming clutch control pressure at the first on-coming clutch KP point, wherein when the first inertia phase reaches a calibrated time of the first inertia phase, the first inertia phase ends, and the first torque phase starts, wherein in the first torque phase, the clutch control module controls the first off-going clutch and the first on-coming clutch based on the feedforward controller calibrated in a single power-on downshift, wherein after the first inertia phase starts, and before the gearshift progress reaches ηs, the second filling phase starts, wherein in the second filling phase, when the gearshift progress does not reach ηs, the clutch control module controls a second off-going clutch pressure to reduce to a minimum oil pressure at which the second off-going clutch does not slip, and the clutch control module controls a second on-coming clutch pressure to reach a second on-coming clutch KP point, wherein when the gearshift progress reaches ηs, the second inertia phase starts, wherein in the second inertia phase, the clutch control module controls the second off-going clutch based on the feedforward controller calibrated in a single power-on downshift, and the clutch control module maintains the second on-coming clutch pressure at the second on-coming clutch KP point, wherein when the second inertia phase reaches a calibrated time of the second inertia phase, the second inertia phase ends, and meanwhile, the second torque phase starts, wherein in the second torque phase, the clutch control module controls the second off-going clutch and the second on-coming clutch based on the feedforward controller calibrated in a single power-on downshift, wherein in the iterative learning control module, learning control parameters of the first off-going clutch and the first on-coming clutch are calculated according to the monitored overshoot of the gearshift progress, which is specifically as follows:
 wherein ΔPOGj+1 represents an iterative learning control parameter of the first off-going clutch under aj+1th overlap downshift, ΔtOCj+1 represents an iterative control parameter of the first on-coming clutch under the j+1th overlap downshift, ΔPOGj represents an iterative learning control parameter of the first off-going clutch under the jth overlap downshift, ΔtOCj represents an iterative control parameter of the first on-coming clutch under the jth overlap downshift, and qOGj and qOCj respectively represent an iterative learning control step length of the first off-going clutch under the jth overlap downshift and an iterative learning control step length of the first on-coming clutch under the jth overlap downshift, wherein in the iterative learning control module, a specific process of the iterative learning control, comprising:
step 1: calculating the gearshift progress overshoot Δηj in a current gearshift progress, wherein the iterative learning control module calculates and stores ηj(tc) and ηj(tm) in real time, and the gearshift progress overshoot is defined as a maximum value of a difference between ηj(tm) and ηj(tc):
 wherein ηj(tc) represents a value of the gearshift progress corresponding to a current moment tc, ηj(tm) represents a maximum value of the gearshift progress between a moment ts and the moment tc, ts represents a moment when the second inertia phase is initiated, tc represents the current moment, tm represents a moment corresponding to ηj(tm), and tf represents a moment when the second inertia phase ends;
step 2: determining whether the gearshift progress overshoot Δηj is greater than a predetermined critical value by 5%;
step 3: if so, calculating the clutch iterative learning control step length according to formula (6); and if not, calculating the clutch iterative learning control step length according to formula (7);
 wherein LOG (Δηj) and LOC (Δηj) respectively represent an iterative learning control step length of the first off-going clutch and an iterative learning control step length of the first on-coming clutch obtained according to the gearshift progress overshoot of the jth overlap downshift by using a look-up table method;
step 4: calculating the iterative learning control parameters ΔPOGj+1 and ΔtOCj+1 of the first off-going clutch and the first on-coming clutch according to formula (8);
 Step 5: storing the iterative learning control parameters ΔPOGj+1 and ΔtOCj+1 of the first off-going clutch and the first on-coming clutch;
Step 6: performing the j+1th overlap downshift of the vehicle in a same working condition;
Step 7: acting the clutch iterative learning control parameters ΔPOGj+1 and ΔtOCj+1 on basic clutch control parameters of the first power-on downshift.
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