Shifting Strategy in Autonomie

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© COPYRIGHT March 2009 UChicago Argonne, LLCALL RIGHTS RESERVED

2© COPYRIGHT March 2009 UChicago Argonne, LLC

Shifting Maps

3

Shifting Strategy Is Based on Shift Maps

4

0 10 20 30 40 50 600

0.2

0.4

0.6

0.8

1

Speed (m/s)

Accel. P

edal

Upshift 12

Downshift 21

Upshift 23

Downshift 32

Upshift 34

Downshift 43

Upshift 45

Downshift 54

𝑎𝑝𝑒𝑟𝑓

𝑎𝑒𝑐𝑜𝑑𝑛

𝑎𝑒𝑐𝑜𝑢𝑝

𝑉𝑒𝑐𝑜𝑑𝑛 𝑉𝑒𝑐𝑜

𝑢𝑝

𝑉𝑝𝑒𝑟𝑓𝑢𝑝𝑉𝑝𝑒𝑟𝑓

𝑑𝑛

Δ𝑉𝑒𝑐𝑜

Δ𝑉𝑝𝑒𝑟𝑓

Upshifting

Downshifting

Shifting maps for default Autonomie Vehicle

Upshifting/Downshifting curves for one gear

Upshifting occurs when (a,V) goes from the left side of the upshifting curve to the right side

Downshifting occurs when (a,V) goes from the right side of the downshifting curve to the left side

Depends on vehicle

Constants

Shifting happens when the couple (acceleration,vehicle speed) [(a,V)] crosses a shifting curve

“Eco-Driving” Shifting Speeds

Up and downshifting vehicle speed in very smooth driving conditions (a=0)

5

𝑉𝑒𝑐𝑜𝑑𝑛 𝑉𝑒𝑐𝑜

𝑢𝑝

Upshifting

Downshifting

Acc

el. P

edal

Po

siti

on

Vehicle Speed

“Eco-Driving” Shifting Speeds Are Based on Engine

Map and Gear Ratios

6

500 1000 1500 2000 2500 3000 35000

1

2

3

4

5

6

engine speed [rpm]

Engine speed operating range (acc=0) for each gear

1st gear

2nd gear

3rd gear

4th gear

5th gear

𝜔𝑒𝑐𝑜2→1: Idle Speed

𝜔𝑒𝑐𝑜2→1=𝜔𝑖𝑑𝑙𝑒 𝑞𝑖𝑑𝑙𝑒

𝜔𝑒𝑐𝑜2→3

𝜔𝑒𝑐𝑜3→4

𝜔𝑒𝑐𝑜𝑁−1→𝑁 (𝜔𝑒𝑐𝑜

4→5):

Best efficiency speed

𝜔𝑒𝑐𝑜1→2:

Idle speed x ratio of ratios

𝜔𝑒𝑐𝑜1→2 = 𝜔𝑖𝑑𝑙𝑒

𝑘1𝑘2

1 + 𝜖𝑢𝑑

𝜔𝑒𝑐𝑜3→2

𝜔𝑒𝑐𝑜4→3

𝜔𝑒𝑐𝑜𝑁→𝑁−1 (𝜔𝑒𝑐𝑜

5→4): - 100 rad/s

𝜔𝑒𝑐𝑜𝑁→𝑁−1 = 𝜔𝑒𝑐𝑜

𝑁−1→𝑁 − 𝜔Δ

Engine Speed (RPM)

Gear

𝜔𝑖𝑑𝑙𝑒: idle speed // k1,k2: gear ratios for gears 1,2 // 𝜖𝑢𝑑: Margin to avoid overlap // 𝜔Δ ≈ 1000 RPM // 𝑞𝑖𝑑𝑙𝑒 : idle ratio (1.1)

To avoid overlap, we verify that 𝜔𝑒𝑐𝑜𝑖→𝑖+1 > 𝜔𝑒𝑐𝑜

𝑖+1→𝑖 ∙𝑘1

𝑘21 + 𝜖𝑢𝑑 , 1 ≤ 𝑖 ≤ 𝑁 − 1

“Performance” Upshifting Speeds

7

0 20 40 60 800

500

1000

1500

2000

2500

3000

3500

Speed (m/s)

Torq

ue @

Whl (N

m)

Gear 1

Gear 2

Gear 3

Gear 4

Gear 5

𝑉𝑝𝑒𝑟𝑓1→2 𝑉𝑝𝑒𝑟𝑓

2→3𝑉𝑝𝑒𝑟𝑓3→4 𝑉𝑝𝑒𝑟𝑓

4→5

• Performance shifting ensures maximum torque output at the wheels • Computed by algorithm (often, but not always, engine top speed)

“Performance” Shifting Speeds

Up and downshifting vehicle speeds “pedal to the metal” (a=1)

8

Upshifting

Downshifting

𝑉𝑝𝑒𝑟𝑓𝑢𝑝𝑉𝑝𝑒𝑟𝑓

𝑑𝑛

Acc

el. P

edal

Po

siti

on

Vehicle Speed

“Performance” Downshifting Speeds

9

𝑎𝑝𝑒𝑟𝑓

𝑎𝑒𝑐𝑜𝑑𝑛

𝑎𝑒𝑐𝑜𝑢𝑝

𝑉𝑒𝑐𝑜𝑑𝑛 𝑉𝑒𝑐𝑜

𝑢𝑝

𝑉𝑝𝑒𝑟𝑓𝑢𝑝𝑉𝑝𝑒𝑟𝑓

𝑑𝑛

Δ𝑉𝑒𝑐𝑜

Δ𝑉𝑝𝑒𝑟𝑓

Upshifting

Downshifting

• The difference between an upshifting and a downshifting curve is twice as big on the top (Δ𝑉𝑝𝑒𝑟𝑓) as at the bottom (Δ𝑉𝑒𝑐𝑜)

• Follows this equation with 𝛼𝑝𝑓,𝑒𝑐 = 2 :

Δ𝑉𝑝𝑒𝑟𝑓𝑖 = 𝛼𝑝𝑓,𝑒𝑐 ∙ Δ𝑉𝑒𝑐𝑜

𝑖

Shifting Logic

10

Shifting Logic (Schematic)

11

𝒂(𝒕)

𝑽(𝒕)

Upshifting Table

𝜸𝒖𝒑(𝒕)

𝒂(𝒕)

𝑽(𝒕)

Downshifting Table

𝜸𝒅𝒏(𝒕) 𝜸𝒄𝒎𝒅(𝒕)

TIMER_UP_SHIFT

HOLD_GEAR

UPSHIFT

𝜸𝒖𝒑 𝒕 > 𝜸 𝒕

𝒂 𝒕 ≤ 𝒂𝒏𝒕

𝒂 𝒕 ≤ 𝒂𝒏𝒕 𝑶𝑹 𝒂𝒇𝒕𝒆𝒓(𝝉)

𝜸𝒖𝒑 𝒕 ≤ 𝜸 𝒕

𝜸 𝒕 = 𝜸𝒄𝒎𝒅 𝒕

𝒂 𝒕 > 𝒂𝒏𝒕

TIMER_DN_SHIFT

𝜸𝒅𝒏 𝒕 < 𝜸 𝒕

𝜸 𝒕 = 𝜸𝒄𝒎𝒅 𝒕

𝒂 𝒕 ≤ 𝒂𝒏𝒕

𝒂 𝒕 ≤ 𝒂𝒏𝒕 𝑶𝑹 𝒂𝒇𝒕𝒆𝒓(𝝉)

𝜸𝒅𝒏 𝒕 ≥ 𝜸 𝒕𝜸(𝒕)

𝒂(𝒕)

State-machine

𝜸𝒄𝒎𝒅 𝒕 ← 𝜸 𝒕 + 𝟏

DOWNSHIFT𝜸𝒄𝒎𝒅 𝒕 ← 𝜸 𝒕 − 𝟏

𝒂 𝒕 > 𝒂𝒏𝒕

𝑎 𝑡 : Accelerator pedal position

𝑉 𝑡 : Vehicle speed

𝛾 𝑡 : Gear

𝛾𝑢𝑝 𝑡 : Upshifting Gear

𝛾𝑑𝑛 𝑡 : Downshifting Gear

𝛾𝑐𝑚𝑑 𝑡 : Gear Command

𝑎𝑛𝑡: accelerator pedal position above

which timer is by-passed

𝜏: minimum time shift criteria

must be met before shift occurs

Simulink Implementation

12

Look-up tables State-Machine

Look-up Tables

13

State-Machine

14

Shifting Strategy in Autonomie

15

Shifting Controller for Automatic Transmissions

16

VEH

VPA

GB

CTRL

DEMAND

Parameterization

17

𝑎𝑝𝑒𝑟𝑓

𝑎𝑒𝑐𝑜𝑑𝑛

𝛼𝑝𝑓,𝑒𝑐

𝑎𝑒𝑐𝑜𝑢𝑝

𝑎𝑛𝑡

𝜔𝑒𝑐𝑜𝑁→𝑁−1

𝜔𝑒𝑐𝑜2→1

𝜔𝑒𝑐𝑜𝑁−1→𝑁

𝜔𝑒𝑐𝑜1→2

𝜏𝜖𝑢𝑑𝑞𝑖𝑑𝑙𝑒

Shifting Controller for Manual Transmissions

18

VEH

DRV

DEMAND

DRV

GEAR

• Model and initialization are different from automatic, but very similar

• Same parameters as for automatic gearbox