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Dynamic Chassis Setups

Did you ever wonder how the chassis for some race cars are set up prior to the cars getting to the track?

Did you ever wonder how the chassis for some race cars are set up prior to the cars getting to the track? In the case of some NASCAR teams, apparently, it is through the use of what’s called a “K-Rig,” which is essentially a test stand that uses hydraulic actuators to apply forces to each of the wheels. This has been available for about the past four years. One supplier of this equipment, Accelerating Developments International (ADI; Concord, NC), decided that the K-Rig could be improved through the replacement of the hydraulic actuators with an electromechanical system. So they devised a way to use electric servos driving ballscrews. While that was comparatively straightforward, a challenge was actually programming the system so that the force and motion control for each of the “wheels” (the actuators are actually bolted to where the wheels would normally be) would be accurate. This led them to the deployment of an eight-axis motion controller from Delta Computer Systems (Vancouver, WA; www.deltamotion.com), the model RMC150. One of the key benefits is that there are flowing motions generated, which is more analogous to the performance of the car on a track. Eight axes? That’s one linear motion system for each of the four wheels, three “aeroloaders” that simulate the effects of aerodynamic downforce, and the remaining one used to simulate steering inputs. The RMC150 gets inputs from magnetorestrictive linear displacement transducers (for position feedback) and load cells that are mounted on each actuator, then provides direct outputs to drive the servomotors are required. And now ADI doesn’t merely offer K-Rigs (with the “K” standing for “kinematics”), but KD-Rigs, with the “D” for “Dynamics.”