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Design and Performance Analysis of a Roll Damping Function for an Electromechanical Active Roll Control System. Meindert Solkesz, Department of Precision and Microsystems Engineering. The Ford Motor Company. a brief introduction. Ford Werke - Merkenich
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Design and Performance Analysis of a Roll Damping Function for an Electromechanical Active Roll Control System Meindert Solkesz, Department of Precision and Microsystems Engineering
The Ford Motor Company a brief introduction • Ford Werke - Merkenich • 500.000 m2 of design centres, test tracks, equipment • Global Advanced Vehicle Dynamics • Active suspensions • Active safety
SUV demonstrator vehicle Range Rover Sport -specs • 4.2L supercharged V8 (390Hp) • Hydraulic Active Roll Control system • Airsprings front & rear • 2700 kg
Terminology Degrees of Freedom • Translational directions • x-direction: longitudinal • y-direction: lateral • z-direction: heave • Rotational directions • θx: roll • θy: pitch • θz: yaw
Terminology suspension • linkages • dampers • springs • stabiliser bar
Stabiliser bar even input uneven input
Stabiliser bar Weak vs. stiff • weak • stiff • Cornering • (handling) • Straight driving • (comfort)
Active Roll Control (ARC) Suspension layout
Active Roll Control Hydraulic vs. Electromechanical system • Hydraulic • pros • Lots of power • Relatively simple • Knowledge available • cons • Continuously running oil pump • Slow • Electromechanical • pros • Energy efficient • Fast • cons • Complex
SUV demonstrator vehicle Range Rover Sport –modifications for eARC • Electromechanical actuators at front & rear • Sensors • Programmable control hardware • Data acquisition hardware • LCD-screen
Software modification motivation • Lack of damping in the implemented actuators • Demand for a roll damping function in the existing control • software • Potential of energy regeneration
Objective “Design a roll damping function for an electromechanical active roll control system (eARC) and analyse its performance” • Steps taken: • Modify veDYNA computer model • Validate computer model with SUV demonstrator vehicle • Modify the eARC controller with a roll damping function • Analyse the open-loop for stability • Analyse the closed-loop performance • Implement the controller in the real vehicle • Performance test of the roll damping function with regard to power consumption, comfort and handling
Validation Kinematics & Compliance test rig
Validation • Parameters that qualified for validation: • Tyre stiffness • Vehicle body mass, COG, inertia and roll centre • Vertical stiffness suspension • Roll stiffness
Roll damping function Control loop
Simulations Performance low level controller
Roll damping function Control loop
Roll damping function Open-loop
Open-loop frequency response Bode plot
Open-loop frequency response Nyquist plot Magnitude Phase
Open-loop frequency response Nyquist stability criterion
Open loop with filter Optimal stability
Performance 4 poster rig measurements
Closed loop response Optimal stability
Closed loop response Optimal performance
Stability optimal performance Nyquist stability criterion
Closed loop response Optimal performance 1.8
1.8 Hz Passive stabiliser bars Active with roll damping
Power consumption 4 poster test • Roll damping function activated • No net energy regeneration
Power consumption 4 poster test
Handling Slalom manoeuvre Without rolldamping With rolldamping
Summary • Computer model modified and validated • Stability analysis performed • Stability improved with the use of notch and phase lead filters • Functioning of the roll damping function judged with regard to power consumption, comfort and handling
Conclusions • Stability of the roll damping feedback loop is improved with a combination of a notch and lead filter. • Filters tuned for optimal stability do not provide optimal performance • The roll damping does not regenerate energy. • The roll damping function has a positive / a negative / no influence on the comfort. • The roll damping function improves the handling.
Validation Vertical stiffness – vertical position
Validation Vertical stiffness - avarage • Rebound stop • Rebound spring • Air bellow • Spring aid
Validation Vertical stiffness – 31 sec bounce cycle
Validation Vertical stiffness - 300 sec bounce cycle
Validation Roll stiffness
Validation Roll stiffness
Active Suspension principles • Fullyactive • energy added • Example: electromechanic/hydraulic actuators at 4 corners • Semi active • no energy added • Example: • damper with adjustable damping coefficients
Vehicle model veDYNA
Controller high-level
Controller low-level
Roll damping function Frequency response