AB Dynamics has launched its next-generation vehicle Kinematics and Compliance (K&C) test machine, named the SPMM Plus (Suspension Parameter Measurement Machine).
The company says it is the world’s most accurate K&C test machine for the automotive industry and enables OEMs to design and test a vehicle’s suspension system in less time. The machine measures and analyses suspension movement whilst subjecting it to a faithful replication of on-road vehicle behaviour. A major Japanese vehicle manufacturer has already invested in the first SPMM Plus, and is currently installing it in its engineering centre.
Conventional K&C machines manipulate the wheels of the vehicle to create the movement and force inputs to the suspension system for analysis. In contrast, the SPMM Plus features a novel moving centre table design that manipulates a vehicle’s body to generate the necessary movement and force. This design means the ground plane (road) remains fixed when simulating vehicle cornering and braking in order to replicate on-road vehicle behaviour more accurately.
The benefit of this architecture is the measurement equipment connected to the vehicle’s wheels remains relatively static. Compared to traditional K&C systems, the travel being measured is an order of magnitude less and the loads being received to the cells are direct, resulting in accurate measurement.
The table is controlled in six degrees of freedom by precision electromechanical actuators, which enable a combination of roll, pitch, bounce and yaw motion to be applied to the vehicle body. As a closed-loop system, it requires no iteration to reach the desired drive commands, which reduces testing time.
Another benefit of the electromechanical actuators is that the machine provides the operator with a safe, clean, and quiet working environment, so it does not need to be housed in a separate control room for safety reasons, as is required for a hydraulic machine. This reduces the cost of installation and maintenance, and allows operators to closely inspect the suspension in action.
The SPMM Plus can also be used as a Moment of Inertia Measurement System, measuring a vehicle’s Centre of Gravity (CoG) and Moment of Inertia (MoI), making it two machines in one. AB Dynamics says that, due to the moving-body, fixed-ground design, the vehicle can be subjected to the full axis rotation required to generate the CoG and MoI faster and more accurately than with traditional machines. As a result, the SPMM Plus generates all the necessary chassis-based data required to create and correlate virtual vehicle models. In this latest version of the SPMM, it is also possible to measure large subsystems, such as battery packs or Electric Drive Units (EDU), to further improve the quality of vehicle simulations.
The machine has also been designed to be future-proof, with a suite of table extenders to cater for the broadening variety of vehicle sizes, particularly longer and lower electric vehicles. The Plus is also fully digitised, running a new and optimised control system, including a high-bandwidth EtherCAT real-time protocol, which is essential for HIL testing.
The SPMM Plus has also been designed with a modular architecture to meet each customer’s testing needs and be easily upgraded for future requirements. For example, this includes the ability to increase the speed of the machine. Increasing the standard speed from 140mm/s to 280mm/s at test frequencies up to 5Hz allows the influence of the damper at the wheel to be explored.
“The industry is shifting rapidly towards virtual testing and validation, and the SPMM Plus is a key tool in that process,” said Matthew Dustan, director of laboratory test systems at AB Dynamics. “Its superior level of accuracy directly translates into better correlating vehicle models, which can be exported in one-click directly into the popular modelling packages. Importantly, in this latest generation of the SPMM, we have also made it Hardware-in-the-Loop (HIL) capable, further increasing its value in an OEM’s virtual development toolchain.
“We have future-proofed the Plus by accommodating all types and sizes of vehicles and ensured that it will be a highly valuable tool in an OEM’s virtual development process.”