Abstract
In control-by-wire systems, the traditional mechanical or hydraulic-mechanical linkages in control systems such as steering, braking, throttling, shifting, and implement controls are replaced with electronically controlled, remote, electric or electrohydraulic actuators to effect the desired action. Fly-by-wire controls have been used in aircraft for many years, but with the advent of low-cost, rugged microprocessors and sensors, x-by-wire systems are now in development for a wide range of on- and off-road vehicles and industrial utility vehicles.
One major hurdle engineers must overcome in developing an x-by-wire system is restoring the tactile feedback lost as a result of removing the mechanical linkage--an important part of the information the operator uses to control the vehicle. Oftentimes, the system must provide "artificial" tactile feedback of equal quality to that of the conventional system it replaces in order to be accepted by the market.
Developing x-by-wire systems requires competency in sensor technology, electronic control systems (hardware and software), mechanical design and hydraulics. Since tactile feedback is a highly subjective quality with many subtleties, the vehicle manufacturing project teams must also have an intimate knowledge of the physical principles behind the operation of the feedback device and its interaction with the rest of the system. Collaborative design with a Company that has expertise in controllable tactile feedback and cost effective designs can ensure successful development of the steer-by-wire system.
This paper will present an overview of technology that is available to vehicle designers for by-wire implementation. Information from the industrial sector will be used to highlight parallels and applicability to the automotive customer. An overview of system components that are commercially available will be highlighted for design engineer consideration.
In conclusion, a survey of Lord´s portfolio of Tactile Feedback Devices (TFD) products based on LORD´s proprietary Magnetorheological (MR) technology will be presented. As a leader in industrial steer-by-wire component manufacturing these "plug-and-play" components incorporate all of the necessary hardware for control-by-wire operator interfaces, can actually improve feel and control while minimizing packaging and cost. For steering applications, these include a controllable, magnetically responsive (MR) rotary brake, shaft, bearings, position sensing and CANbus communication capability.
Keywords - TFD, steer-by-wire, tactile, feedback, MR