An armored Chevrolet Suburban equipped with Pi Innovo’s OpenECU for active damping control.
Active Damping System for Commercial Armored Vehicles
Adding 3000lb+ mass to the vehicle body when armoring the passenger compartment significantly raises the center of gravity, adversely affecting:
Increased risk of roll-over
Soft springs – too much body motion
Hard springs – harsh ride
Traction on rough surfaces
Harshness, jounce crash, etc.
Pi Innovo, working with an armored vehicle manufacturer, developed a solution to the stability and ride control challenges presented by armored passenger vehicles – the Active Damping Control System – and installed it on a 2011 Chevrolet Suburban demonstrator vehicle.
This system provided enhanced safety, stability and control by actively adjusting damping forces to match vehicle operating conditions
As speed increases, more damping is provided to maintain control and give greater ride comfort
During braking, more damping is provided to control front suspension dive and give greater control for maneuvering
At low speeds, less damping is provided to give optimum traction and ensure ride comfort is maintained
Pi Innovo’s system included a low cost embedded controls Electronic Control Unit (ECU), electronically-controlled dampers, accelerometers, and the associated wiring harness to connect with the vehicle for power and CAN bus communications.
All four conventional dampers on the vehicle were replaced with electronically-controlled dampers.
Accelerometers were mounted to the axle or wheel hub at all four corners of the vehicle, to determine each damper’s instantaneous direction of travel.
A Pi Innovo OpenECU M250 rapid controls prototyping controller, including model based control software, was used to provide the electrical current supplied to the electronically-controlled dampers.
The ECU utilized two CAN channels: one to communicate with a programming and calibration tool, and the other to receive vehicle CAN bus messages, such as vehicle speed and brake status.
The system adjusted damping forces at each wheel, based upon a combination of inputs:
Vehicle Speed (CAN message)
Brake Actuation (CAN message)
Wheel Travel Direction (accelerometer)
Steering Wheel Angle (CAN message)
There are several types of commercially-available electronically-controllable dampers. The prototype system installed on Pi Innovo’s Chevrolet Suburban demonstrator vehicle utilized off-the-shelf GM MR-fluid type dampers.
Alternatively, the Pi Innovo Active Damping Control System was designed to support an electronically-controlled needle-valve type damper.
Results and Impact
During vehicle testing in comparison to a vehicle in typical armored configuration, the ride quality and handling were seen to be greatly improved and much closer to the base vehicle’s pre-armoring ride performance.
In summary, the benefits of active damping control seen were:
Better comfort and ride across a variety of terrains
Better dynamic handling
Increased traction on rough surfaces
Decreased risk of vehicle roll over
Increased vehicle durability due to decreased shock and vibration (estimated; no durability testing was undertaken, but no failures were seen).
Luke Hayward, former US Army Special Forces and now CEO of Kinetic Options LLC, who provide driver training for current Special Forces operators, described a Chevrolet Suburban with this kit:
“With the advanced suspension system, [it is] by far the best armored NTV [Non-Tactical Vehicle] I have ever driven”, and that “During driver training maneuvers the Special Forces operators…all commented that the armored Suburban with the Active Damping Control System was the best handling armored vehicle they had ever driven.”
Kurt Delia, former SWAT Team leader and now President of Delia Tactical International, having conducted driver training using a Chevrolet Suburban with Pi Innovo’s suspension system, commented:
“I was extremely impressed with the quality and performance of the vehicle… [the] suspension system is second to none and far exceeded our staff driving instructor’s expectations”.
The project consisted of software development, hardware integration, on-vehicle testing and software calibration.
The demonstrator system consisted of the following:
Armored 2011 Chevrolet Suburban
From the armored vehicle manufacturer partner
Off-the-shelf GM suspension components
MR dampers from Cadillac Escalade/GMC Yukon Denali
Up-rated springs and jounce bumpers
Selected by the armored vehicle manufacturer partner
“Helper” springs left off (typically used in this application)
Short jounce bumpers (long bumpers typically used in this application)
Pi Innovo OpenECU rapid controls prototyping controller
With custom model based software calibrated for this vehicle
The project was three months in initial development and approximately one month of tuning and evaluation time (spread over an additional three months).