Implementation of Active Steering on a
Multiple Trailer Long Combination Vehicle
Dr A.M.C. Odhams
Dr R.L. Roebuck
Prof. D. Cebon
Overview
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Background Forward mo/on Reversing Conclusions Acknowledgements - CVDC
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Volvo Trucks Arvin Meritor Goodyear Tyres Firestone Industrial Products Haldex Brake Products Qine=q Tinsley Bridge Limited Shell Oil Fluid Power Design Mektronika Systems MIRA Ltd FM Engineering Denby Transport Ltd Camcon Background: Active Steering
Ac=vely steer all trailer wheels Path-­‐Following Steering strategy ‘CT-­‐AT’: Lead Point (LP) Follow Point (FP) –  Perfect tracking of any path at any speed –  LP and FP: same heading angle at a par=cular point on the path –  Equalize tyre forces Background: First Active Trailer
•  Low and high speed path following
•  Eliminates path tracking errors, tyre wear, RA
New B-Trailer
•  Exis=ng semi-­‐trailer with ac=ve rear steering. •  New steered b-­‐trailer 40ft
30ft
•  Rear por=on detachable to form steered dolly.  Low & high speed control: forward & reverse Background: Hardware
24v
Pump
Pump
VC
TC
TC
•  Control system Radius Arms –  VC, TC –  CAN linked –  Sensors (Ar=c, steer) Actuator •  Hydraulic Pumps –  One per trailer –  Electrically powered Tie Rod •  Actuators: –  Hydraulic –  Controlled individually Background: Roundabout Manoeuvre
11.25m 8.9m
12.5m 
5.3m 
Background: The need…
Overview
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Background Forward mo/on Reversing Conclusions Command Steer Control
Control: –  Imaginary unsteered axles –  Steer to common center –  Account for unit in front steering B
Pros: –  Simplest to implement –  Few sensors (Ar=c x 2) A
Cons: Transients –  Low-­‐speed tail-­‐swing –  High speed instability and RA CT-AT-AT Control
Control: B
A
•  Calculate steer angles for perfect tracking •  Steer wheels to these angles •  Data needed from unit ahead (if steered) •  Sensors: Ar=c x2, tractor speed & tractor steer Pros: •  Perfect tracking Cons: •  Trailers not independent Testing: Path Tracking Cameras
Tail Swing
Tail Swing
Cut In
Cut In
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3 cameras (Hitches & Rear) Line(s) on track Time lapse (1 strip per frame) Calibrated for offset Command Steer: Video
Command Steer: Results
Tail Swing
A-trailer rear doors
Cut-in
B-Hitch
Tractor 5th wheel
•  Tractor 5th wheel 1.1m cut-­‐in •  B: Tail-­‐swing (0.5m) •  A: Tail-­‐swing 1.65m, cut-­‐in 2.5m •  Blind spot •  Exit se_ling CT-AT-AT: Video
CT-AT-AT : Results
Tail Swing
A-trailer rear doors
Cut-in
B-Hitch
Tractor 5th wheel
•  B follows tractor (<0.3m) •  A follows B (<0.4m) •  Tail-­‐swing eliminated (A and B) •  Cut-­‐in eliminated Results: Summary
COMM
CT-AT-AT
Cut in [m]
2.5
1.1
Tail Swing [m]
1.65
0.0
Exit Settling Dist [m]
10.0
0.0
Overview
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Background Forward mo/on Reversing Conclusions Path Following Reversing (AT-ATCT)
Control: B
–  Joys=ck Control of rear –  Automa=c control of tractor –  Calculate steer angles for perfect tracking –  Ar=c x2, tractor speed, joys=ck, camera Pros: A
–  Perfect path following Cons: –  Automa=c tractor steering required –  Tractor hitch off-­‐tracking ‘Teardrop’: Manoeuvre
B A 12.5m
•  Test similar to roundabout •  12.5m radius gives steer angle overhead •  Tractor steering computer controlled (driver actuated) AT-AT-CT: ‘Teardrop’ Video
‘Teardrop’ : Results
B-Hitch
Tail Swing
Cut-in
A-trailer rear
doors
Entry
Exit
Tractor
5th wheel
•  Driver error <1m •  B-­‐hitch follows to <0.4m •  Tractor off-­‐
tracking at entry, and when driver error •  Automa=c tractor steering would improve Conclusions
1.  Trailer Steering is needed for introduc=on of LCVs in UK 2.  Path-­‐following steering controller devised and implemented on B-­‐Double: –
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Controllers for Forward and Reverse Mo=on Eliminates tail-­‐swing, cut-­‐in and tyre wear Overcomes deficiencies of Command Steer 4 sensors needed 3.  Future Work –  Automated tractor steering in reverse –  High speed controller be tested (reduc=on of RA)