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UK-based test systems company Anthony Best Dynamics has introduced a new version of its Suspension Parameter Measurement Machine (SPMM) for dynamic kinematic and compliance testing as well as quasi-static testing.

The SPMM 4000 helps reduce time to market for new vehicles and can be used on vehicles from small passenger cars through to light trucks and MPVs.

The system can be supplied as a two- or four-wheel installation. The four-wheel station measures both axles of a vehicle at the same time and can turn around a complete vehicle in only a few hours with a full set of suspension and steering measurements. Set-up time is further reduced with wheel centering compensation software.

Dynamic testing has been made possible through high speed actuators capable of vertical excitation at 5 Hz at speeds of 140 mm/s.

The SPMM 4000 HS records wheel displacements and the forces and moments occurring at the tyre to road interface, caused by bounce, roll and pitch of the vehicle body and also by the application of simulated cornering, braking and traction forces.

These include the kinematic characteristics due to suspension and steering system geometries, and compliances due to suspension springs, anti-roll bars, elastomeric bushes and component deformations.

The SPMM 4000 HS uses the new ABD Dynamic Arm wheel measurement system. Each arm has five high resolution rotary encoders and two high resolution linear encoders. The ABD Dynamic Arm has a dynamic measurement capability of 5 Hz, with measurement accuracies at 2 Hz of:
• 0.02 mm or better for displacements of up to ±10 mm and 0.05 mm or better for larger displacements up to ±75 mm
• 0.004° or better for steer, wheel spin and wheel camber displacements of up to ±1° and 0.01° or better for larger angles up to ±1°.

The measurement cross talks with the ABD Dynamic Arm are also considerably lower than for the corresponding draw wire encoder wheel position measurement system used on the existing SPMM 4000.

Using the SPMM 4000 HS system, parameters that can be measured include; suspension kinematic characteristics such as bump-steer and roll-steer, and suspension compliance characteristics such as suspension rates and roll stiffness. The kinematics and compliance characteristics of the steering system are also measured.