Development of a Novel Wheel Speed Sensor for Enhanced Close-Loop Feedback Control of Vehicle Mobility
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The maximization of vehicle mobility in off-road environments requires implementation of real-time control systems that govern individual wheel rotational velocity based on closed-loop feedback from wheel rotation sensors. A paradigm shift in the type of feedback sensor is required to facilitate faster vehicle control loop speeds such that a subsequent paradigm shift can be realized in vehicle mobility control. This anticipated shift in vehicle mobility is facilitated by a transition from the traditional reactive control paradigm (response time of 100–150 ms) to an agile control paradigm (response time of 40–60 ms); wherein adjustments can be made within the tire relaxation time.
A novel wheel speed sensor (WSS) was developed to demonstrate possible improvements over the two main types of conventional OEM wheel speed sensors that use toothed reluctor rings; passive variable reluctance sensors, and active magneto resistive sensors. The number of teeth on a given reluctor ring fundamentally limits the resolution these OEM sensors can provide to the mobility control systems of a vehicle (e.g., traction control, anti-lock braking, wheel torque vectoring) – thereby limiting vehicle mobility. The output of these OEM sensors are in the style of incremental encoders that produce a discrete pulse train signal where the real-time control system must measure the duration of a full pulse or period to obtain each measurement of wheel speed. This technique of measurement introduces: (1) latency, in that the control system must wait for next signal transition before measurement is made, and (2) error, in that the wheel speed measurement is an unweighted average over the whole pulse/period duration. To eliminate these measurement limitations, a paradigm shift was required such that the output of the feedback sensor is instead a continuous signal.
The top level design of the novel WSS built upon work done previously to theorize the configuration and behavior of such a continuous output sensor. The design was then reduced to practice through an iterative series of design with multi-physics simulations and laboratory validation at the component and subsystem levels. The novel WSS was then implemented alongside two OEM sensors for experimental test and evaluation on an MTS Flat-Trac LTR Tire Test System during dynamic testing of an off-road truck tire (Continental MPT 81365/80 R20). In these tests, the novel WSS sensor demonstrated a significant improvement to measurement latency during low speed acceleration of more than 200 ms, and provided data for use in the design and evaluation of new vehicle control systems to determine comparative measurement error and alternative techniques for measurement of high wheel speeds. This demonstrated improvement to measurement latency from more than 200 ms down to <5 ms, is more than sufficient to facilitate the desired subsequent paradigm shift in overall vehicle mobility control.
KeywordsWheel speed Feedback sensor Vehicle mobility
This study has been supported by a grant of the NATO Science for Peace and Security Programme: MYP SPS G5176 “Agile Tyre Mobility for Severe Terrain Environments”.
- 1.Nishikawa K, Takahashi T, Duret C (2013) Hub bearing with an integrated high-resolution rotation sensor, NTN-SNR Roulements. Technical Article No. 81Google Scholar
- 2.Paldan JR (2015) Sensor signal limitations in Wheel rotational kinematics estimation model. In: Proceedings of the ASME 2015 dynamic systems and control conference (DSCC2015–9769), Columbus, Ohio, USAGoogle Scholar
- 3.Gray J, Paldan J, Vantsevich V Multi-domain modelling of a new wheel rotational kinematics. In: Proceedings of the 24th symposium of the international association for vehicle system dynamics (IAVSD 2015). CRC Press, Graz, pp 253–262Google Scholar
- 4.Gray JP, Paldan JR, Vantsevich VV (2015) An agile tire slippage estimation based on new tire and wheel rolling characteristics. In: 13th European conference of the ISTVS 2015, at Rome, ItalyGoogle Scholar