Active Suspension

See it in action

Bring Modern Vehicle Design to Your Lab

The Active Suspension is a bench-scale quarter-car model ideal to introduce principles of active control. It offers senior mechanical engineering students unique hands-on learning relevant to today’s automotive industry. Students learn how to:

• mathematically model the Active Suspension
• obtain a state-space representation of the open-loop system and do open-loop analysis
• obtain different transfer functions for the experiment as MIMO system
• design a Linear Quadratic Regulator (LQR)
• simulate the LQR controller using a model of the plant to ensure the controller specifications are met
• implement the LQR-based state-feedback controller on the system and evaluate its performance
• observe and investigate the response of the suspension system to road disturbances

In addition to teaching active control concepts, the Active Suspension can be also used for research in various areas, including vibration isolation and neural networks.

How It Works

This Active Suspension system consists of three masses, or plates. Each mass slides along stainless steel shafts using linear bearings and is supported by a set of springs. The upper mass (blue plate) represents the vehicle body supported above the suspension, also known as the sprung mass. The middle mass (red plate) corresponds to one of the vehicle’s tires, or the unsprung mass. The bottom mass (silver plate) by moving vertically simulates the road surface.

The upper mass is connected to a high-quality DC motor through a capstan to emulate an active suspension system that can dynamically compensate for the motions introduced by the road. The lower plate is driven by a powerful DC motor connected to a lead screw and cable transmission system. It is used to simulate different road profiles.

Students can tune the supplied controller or design their own controllers to optimize the various suspension performance parameters, including:

• ride comfort - is related to vehicle body motion sensed by the passengers. It can be measured using either the accelerometer mounted on the top plate, or the encoder (for a direct position measurement).
• suspension travel - refers to relative displacement between the vehicle body and the tire and is constrained within an allowable range of motion. This can be measured using the suspension encoder mounted on the capstan.
• road handling - is associated with the contact forces between the road surface and the vehicle tires and depends on tire deflection. Tire deflection is a relative displacement between the tire and the road and can be measured using all the encoders.

Quanser-developed Courseware Included

The Active Suspension comes with the Quanser-developed courseware. A comprehensive Laboratory Guide, together with quick start resources, a User Manual, pre-designed controllers and a system model allow you to get your lab running faster, saving months of time typically required to develop lab materials.

• Multi-coloured masses representing vehicle body, vehicle tire and road surface for easy distinction
• Three high resolution encoders to measure positions of bottom and top masses, as well as suspension deflection
• 226 W MICROMO brushless DC motor connected to capstan for active suspension control
• 70 W MICROMO brushed DC motor connected to belt-drive mechanism for road actuation
• Adjustable weight and spring stiffness
• Accelerometer mounted on top plate to measure vehicle body acceleration
• Accelerometer measurements as sensory input
• Responsive belt-drive mechanism to simulate the road surface
• Limit switch and protection circuit
• Heavy-duty and robust machine components
• Fully compatible with MATLAB®/Simulink® and LabVIEW™
• Fully documented system models and parameters provided for MATLAB®, Simulink®, LabVIEW™ and Maple™
• Open architecture design allows users to design their own controller
 Dimensions (W x L x H) 30.5 cm x 30.5 cm x 61 cm Total mass 15 kg Range of motion ± 22 mm (road), ±19 mm (tire), ± 25.4 mm (car) Position resolution 0.002 mm/count (road), 0.005 mm/count (tire), 0.009 mm (car) Stiffness adjustable from 0.4 to 2 N/mm Excitation frequency up to 15 Hz Resonant frequency configurable between 2 to 6 Hz Accelerometer sensitivity 9.81 m/Vs²

Topics included in the Quanser-developed courseware:

• Double mass, spring, damper system analysis
• Industry-relevant control requirements (ride comfort, suspension travel, road handling)
• Derivation of dynamic model
• State space representation
• System transfer functions
• Open-loop system analysis
• Time-domain and frequency-domain open-loop and closed-loop system identification
• Full-state/two-state feedback LQR control design (with real-time control parameter tuning)
• Full-state/two-state feedback LQG controller (with real-time control/observer parameter tuning)
• Observer design
The Active Suspension can be also used to teach other topics that are not included in the Quanser-developed courseware.

To set up your Active Suspension workstation, you need additional components. Quanser engineers recommend:

 for MATLAB®/Simulink® users for LabVIEW™ users 1x Q8-USB data acquisition device¹ 1x AMPAQ-L2 linear current amplifier² 1x AMPAQ-L2 linear current amplifier² Quanser Rapid Control Prototyping toolkit software QUARC real-time control software and one of the following options: - 1x NI CompactRIO³ controller with 2x Quanser Q1-CRIO module - 1x NI M- or X-series data acquisition device4 with 1x Quanser NI Terminal Board

¹ alternatively, you can use QPIDe or any equivalent NI DAQ device supported by QUARC
² alternatively, you can use AMPAQ-L4 amplifier

³ NI cRIO-9074, or NI cRIO-9024 with cRIO-9113 or cRIO-9114 chassis
4 NI DAQ device must be supported by Quanser RCP toolkit. Alternatively, you can use Quanser Q8-USB, or QPIDe

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