Indices and Computational Strategy for Unmanned Ground Wheeled Vehicle Mobility Estimation and Enhancement

Abstract

The United States Army began developing Unmanned Ground Vehicles (UGV) in the early 1900’s. Concurrently, researchers developed and enhanced passenger and commercial ground vehicles. Although significant progress has been made for improving vehicle mobility for all ground vehicles throughout the past century, mobility has lacked a concise mutually agreed definition and analytical standardized criteria. The implementations of improved technologies, such as vehicle traction control, stability control, and torque vectoring systems require researchers to take a step back and reevaluate mobility criteria. UGVs require additional enhancement to include on-line mobility estimation since the vehicle cannot predict nor anticipate terrain conditions on their own prior to the vehicle traversing those conditions. This paper analyzes methodologies researchers have employed for defining and improving vehicle mobility of wheeled vehicles. The analysis is done from a view point of concurrent mobility methodologies’ enhancement and applicability to wheeled UGVs. This analysis is then used to develop off-line and on-line analytical criterion for mobility estimation, and to derive a strategy which can be applied to wheeled vehicles, both manned and unmanned. The on-line mobility estimation enables the UGV to make control changes as the events occur rather than after the event, causing the vehicle to then optimize its reaction to regain control.

Fuzzy controller, designed by reinforcement learning, for vehicle traction system application

“…(11)- (12). Wheel mobility index W M I is the value in percentage that was introduced in [28] to determine the margins of mobility performance of the wheel in different road/terrain conditions and at every particular moment of time. In general, 0% of wheel mobility index means the wheel have lost mobility (is spinning or skidding) and is out of control at the particular moment that could cause critical motion situations.…”

“…where, V t is the theoretical longitudinal velocity at zero slippage, V x is the actual velocity of the wheel's center, ω w is the angular velocity of the wheel and r w is the tire rolling radius in the driving mode. Apart from tire slippage analysis, a wheel mobility index is introduced in [28] for online computation of mobility performance of the wheel and is presented as follows…”

Multi-vehicle convoy mobility in severe terrain conditions: Factor impact analysis, estimation and control strategy

“…The Engine/Transmission vs. Driveline Control gives instructions on changing the driveline configuration that will be implemented in (j + 1) -moment of time. Therefore, the proposed strategy is pre-emptive by its nature allowing for pro-active control of every wheel mobility and mobility of the vehicle as a whole (Gray et al, 2013). The mobility estimation strategy enables the vehicle to eliminate general immobility situations by reconfiguring the driveline system toward correcting the power distribution between the drive wheels.…”

“…The above-described and other mobility-wise challenging situations caused by inappropriate wheel power distributions can be included in convoy mobility modeling and estimation by utilizing indices from the previous paper of the authors (Gray et al, 2013). Where they introduced the wheel mobility index as WMI 0ð00Þ…”

“…In Gray et al (2013), the authors presented a generalized strategy for on-line computational mobility estimation using newly developed WMI and VMI presented in Eqs.…”