CHASSIS CONTROL

Pi Innovo has extensive experience using automotive electronic controls to improve all aspects of dynamic vehicle performance.

Specific experience includes a system that controls active suspension struts and dampers, modify differential output, apply braking and adjust the aerodynamics of the vehicle. These systems model the vehicle attitude and driver intention to adjust the vehicle controls, optimizing stability and performance.

Pi Innovo-designed systems are improving a wide range of vehicles, from boutique supercars to off-highway and military vehicles that tackle the most arduous terrains.

Our flexible range of customizable OpenECU modules includes the M461, with 3-axis accelerometer and 3-axis gyroscopic sensors that can be used for initial rapid prototyping and as the basis for volume solutions.

Pi Innovo’s engineering teams, utilizing OpenECU controllers and platform software have developed multiple systems providing dynamic suspension control to a wide range of vehicle types for applications as varied as high-performance sports cars, commercial transportation and military transport vehicles.

Active and semi-active suspension systems control the forces generated in adjustable suspension components such as struts, or shock absorbers. Control of the damping and spring force/ride height on individual wheels enables optimization of ride characteristics, dynamic handling, pitch control, and roll-over mitigation.

Fully active systems have the ability to bi-directionally adjust the control forces in the suspension components, while semi-active systems apply force in a single direction. Fully active suspension systems are in use on high-performance on-road sports and luxury cars. Semi-active systems are best suited to off-highway, heavy-duty and military vehicles required to navigate rugged terrain and/or have wide empty to heavily-loaded weight ranges and benefit from maintaining a consistent ride height regardless of overall vehicle weight.

In addition to improvements in dynamic performance, functions such as variable ride height are of great benefit in on/off-highway and defense applications, Typical operational conditions experience rugged low-speed off-road terrain and smooth paved highways in the same mission, requiring a substantially different ride height and suspension control strategy for each.

The ability to adjust the vehicle to a level position, independent of the ground plane, provides assistance with opening and closing armored doors on military vehicles and is used on public transport applications such as buses that lower to aid passenger entry and exit.

Pi Innovo’s engineering team, in collaboration with a major Tier1 driveline component supplier, developed a torque-based traction control system for an off-highway vehicle application. Using an off-the-shelf OpenECU controller and custom algorithms, Pi enabled control of three electro-hydraulic limited-slip differentials installed on a 4WD vehicle.

Through closed-loop control of the front/rear split differential, as well as individual wheels on each axle via their respective differentials, the system provided a level of traction control not previously possible on the vehicle platform. Significant improvements in driver workload, driveline wear and overall vehicle mobility were recorded.

Pi Innovo’s engineering team has extensive experience in the development of sophisticated brake-based stability managements systems, combining ABS and TCS systems into an overall Electronic Stability Control (ESC) system, to improve passenger car, light-duty commercial and military vehicle applications.

A brake-based ESC system takes anti-lock brake and traction control functions into two dimensions. The system can detect excessive vehicle over-steer and under-steer using integrated inertial sensors and vehicle dynamics software models. Mitigation of excessive under-steer or over-steer is performed by the system through the application of one or more individual wheel brakes, inducing a yaw moment on the vehicle, which is intended to correct the undesirable behavior.

The flexibility of the OpenECU platform allowed Pi Innovo’s team to implement sophisticated brake based stability algorithms on a vehicle platform with weights up to 22,000lb and successfully meet the requirements of FMVSS126 within 14 months of project inception.

When traveling at speed, aerodynamic lift on a vehicle body can significantly reduce the down-force on each wheel, resulting in a dynamic imbalance and degradation of stability and traction.

Pi Innovo engineers have developed electronic systems derived from OpenECU technology to control the aerodynamic forces acting on the vehicle through adjustable ride heights and deployment of adjustable spoilers. The spoilers are automatically deployed to increase down-forces as vehicle speed increases, enhancing high-speed stability, and returning to an aerodynamically efficient position at low speed, thus reducing drag for optimized fuel consumption. In these sophisticated systems, the application of vehicle brakes in certain speed ranges is also utilized as an input to the aerodynamic control software, allowing for spoiler deployment, providing an increased level of traction and stability during braking events.

The aerodynamic control system also lowers the vehicle at speed via pneumatic ride height to adjust the system at each suspension corner. The effect of lowering the vehicle is to reduce the volume of air passing under the vehicle and control the overall attitude of the vehicle body, minimizing the lifting effect of high-speed airflow without significantly increasing aerodynamic drag.

OpenECU-based active aerodynamic control systems are also being utilized to manage airflow through the engine cooling system. In accordance with target engine operating temperatures across a wide range of loads, air speeds and ambient conditions, the aerodynamic controller actively manages the air path through the cooling system by actuating devices such as electronically-controlled shutters, louvers and doors to minimize drag while maintaining ideal airflow conditions to meet the cooling requirement. Similar systems are applied to brake cooling management, providing optimum air flow to control brake temperature while minimizing aerodynamic drag.