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Valentin Ivanov

on 14 February 2015

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Transcript of ISTVS2014

Wheel Slip Control for
All-Wheel Drive Electric Vehicle
The 18th International Conference of the ISTVS
Valentin Ivanov, Dzmitry Savitski, Klaus Augsburg
(Ilmenau University of Technology - Germany)

Bernhard Knauder, Josef Zehetner
(Virtual Vehicle Research Center - Austria)

Phil Barber
(Jaguar Land Rover - UK)
Vehicle architecture
Wheel slip controller
MIL/HIL tests
Proving ground tests
Conclusions and future works
Demand for Wheel Slip Control in Off-road Vehicles
Stability Control /
Torque Vectoring
Control targets:
Tyre energy dissipation & slip losses
Cross-country ability
Lateral stability & agility
Ride & pitch comfort
Research & Development Targets
Main challenge: AWD full electric vehicle
Unified structure of anti-lock braking and traction controller
Continuous vs. rule-based control
Full ABS functionality also in terrain/rough road conditions
Different strategies incl. pure electric ABS without friction brakes
Vehicle Architecture
Technical Data
Flexible transformation in FWD / RWD / AWD platform
Individual on-board motors
Total weight 2100 kg
Max. speed 195 km/h
Tyres 235/55 R19
Electric Motors and Driveline
Switched reluctance motors
Peak 200 Nm/100 kW
Nominal 135 Nm/42 kW
Max. speed 15,000 1/min
Motor transmission
2-stage reducer with helical gears
Gear ratio: 1:10,5
Torsional stiffness 6500 Nm/rad
Electro-Hydraulic Brake System
Decoupled architecture
Max. operational pressure 180 bar
Pedal position sensor
Internal ABS controller (failsafe)
Wheel Slip Controller
Controller Structure
Feed-forward (predictive) part
(reactive) part
Controller Features
Continuous PI-control of electric motors
Switching between traction/braking modes
Desensitization of wheel torque modulation by recognition of rough/terrain road
Three different ABS modes: pure electric, pure electro-hydraulic, or blended torque modulation
Controller logic: SAE Technical Paper 2014-01-9128
Model-in-the-loop /
Hardware-in-the-loop Tests
Vehicle Simulator and HIL Test Rig
Case Study: ABS/TC Desensitization by Terrapod Maneuver
Up and down
Side slope
Walking holes
Proving Ground Tests
Test Configuration
Kistler RoaDyn S635 - wheel forces and torques
Corrsys Datron - vehicle velocity
Longitudinal / lateral accelerometers
Braking on inhomogeneous low-friction surface
Tip-in maneuvers
Torque step response
Variation of tyre inflation
Transient braking from high- to low-friction surface and vice versa
Terrapod driving
Down- and up-hill driving
Test programme on Ford proving ground at
Lommel (Belgium)
Case Study: Slip Control by Braking
on Inhomogeneous Low-friction Surface
Irregular tyre-surface friction coefficient: 0,2...0,4
Considerable unevenness of the ground (wet basalt elements)
Optimal traction/braking area corresponds to very low slip values: 4...7%
Test Results: ABS Benchmarking
Hydraulic ABS braking
Pure electric ABS braking
Test Results: ABS Benchmarking
Pure electric ABS guarantees required level of vehicle deceleration
Shorter brake distance (up to 15%) as compared with commercial electro-hydraulic ABS
Accurate tracking of wheel slip
No jerk effect
Conclusions and Future Works
Feasibility of continuous wheel slip control for AWD full electric vehicle
Efficiency on rough inhomogeneous surfaces is confirmed
Direct individual torque control of electric motors is advantageous for TC / ABS functions
Integration with other control systems like torque vectoring, active suspension and dynamic tyre pressure management
Implementation of new electric powertrain architecture (direct in-wheel motors) to off-road mobility
Future R&D directions:
Full transcript