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Anthony Best Dynamics has completed the installation of a new suspension parameter measurement machine (SPMM) at the Higashi-Fuji Technical Centre of Toyota Motor Corporation in Japan.

Kinematics and compliance (K and C) testing of vehicles is at the forefront of Toyota’s research-and-development activities in Japan.

The market for suspension measurement machines for K and C testing continues to expand as it provides parameter values and characteristics that are an essential aid to the understanding of a vehicle’s performance in terms of steering, handling and ride.

After a thorough selection process, Toyota decided that the SPMM 4000 HS from Anthony Best Dynamics (ABD) provided the best technical solution to meet the company’s requirements.

Capable of being used for both dynamic and quasi-static testing, the SPMM 4000 HS has replaced the K and C equipment previously used at Higashi-Fuji and provides the team there with a system providing the latest features for K and C testing.

For example, the SPMM 4000 HS uses the ABD Dynamic Arm wheel-position measurement system that allows Toyota engineers to carry out dynamic K and C testing.

Utilising five high-resolution rotary encoders and two high-resolution linear encoders, the ABD Dynamic Arm has a dynamic measurement capability of 5Hz, with measurement accuracies at 2Hz of: 0.02mm or better for displacements of up to +/- 10mm and 0.05mm or better for larger displacements up to +/- 75mm; 0.004deg or better for steer, wheel spin and wheel camber displacements of up to +/- 1deg; and 0.01deg or better for larger angles up to +/- 1deg.

To meet Toyota’s high-frequency, high-speed testing requirements, the SPMM 4000 HS incorporates a high-speed version of the centre table Rollaram actuators.

The actuators provide the system with the capacity to move at higher speeds while keeping the high stiffness and low levels of hysteresis and backlash that are required for high-accuracy quasi-static testing.

The SPMM 4000 HS also features motors and amplifiers for many of its actuators to provide the power needed to drive the rig at the speeds and frequencies specified by Toyota.

Again, this required careful design and testing work by ABD in order to maintain zero backlash and low cogging levels.

A number of software and control system developments have been made in the SPMM 4000 HS to meet Toyota’s requirements.

The provision of automatic wheel-plate alignment compensation simplifies the vehicle set-up procedure, reducing set-up time and improving measurement accuracy.

In addition, ABD had to utilise adaptive control techniques to enable horizontal plane wheel forces to be controlled at up to 5Hz.

Other features that increase the capacity of the Toyota SPMM 4000 HS include the large roll pitch bounce table extenders, which enable vehicles with bigger wheelbases to be fixed securely to the SPMM table.

The large extenders increase the table width from 1700mm to 2375mm.

The wheel station X tables have also been extended, which together with modifications made to the centre table allows the Toyota SPMM to test vehicles with a wheelbase of up to 4540mm.

In addition, wheel-pan extenders have been provided for the rear wheel stations that allow vehicles (typically small trucks) with twin wheels on the rear axle to be tested.

The four-wheel station version of the SPMM 4000 HS at Toyota can measure both axles of a vehicle simultaneously and provides a fast turnaround of just a few hours for producing a full suite of suspension and steering measurements for a vehicle.

In operation, the SPMM 4000 HS automatically subjects the suspension and steering of a vehicle to a variety of forces and displacements and measures the effects.

The SPMM 4000 HS records the 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.

Using the SPMM 4000 HS system, Toyota is now measuring a large number of parameters under quasi-static and dynamic test conditions, including suspension-kinematic characteristics such as bump-steer and roll-steer, and suspension-compliance characteristics such as suspension rates and roll stiffness.

The K and C characteristics of the steering system are also measured.

Anthony Best Dynamics

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