Steer-by-Wire Systems with Integrated Torque Feedback Improve Steering Performance and Reduce Cost

These cleaning machines were originally designed with direct-drive steering and electrical torque assist. Nilfisk-Advance engineers made the decision to upgrade the steering system to electronic steer-by-wire in order to improve steering performance, reduce power consumption, and make it possible to add additional features. “We considered hydraulic steering; however, the vehicle only has a small hydraulic power pack used for lifting the hopper and closing the dump door,” said Kurt Vetse, mechanical engineer. “This power pack is designed for intermittent use so going to hydraulic steering would have required a new continuous-duty power pack. This would have significantly increased the cost of the steering system. We didn’t want to devote the extensive resources or expose ourselves to the risk that would have been required to develop our own steer-by-wire system from scratch. So we looked at three leading commercial steer-by-wire solutions. We selected the Thomson unit because of its compact size and low cost.”

The integrated steer-by-wire unit incorporates all of the capabilities needed for steer-by-wire, including torque feedback technology that provides repeatable performance over time and temperature and no torque at zero current. The steer-by-wire unit bolts right on to the existing gearbox that Nilfisk-Advance uses to turn the steered wheel, and fits within the existing console. Nilfisk-Advance engineers adjusted the torque feedback to simulate the hydraulic steering systems that many customers are used to. They configured the unit to provide fewer lock-to-lock steering wheel turns than are required by most hydraulic systems to reduce the amount of operator effort. They also decreased the level of steering sensitivity when the vehicle is going straight in order to make it easier for the operator to keep the vehicle on a straight path.

This article was written by Geoff Rondeau, Product Manager, Thomson Industries, Inc., Wood Dale, IL. For more information, visit http://info.hotims.com/34455-320

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