A dynamically switchable torque distribution strategy of all wheel omnidirectional independent steering vehicle in multi-steer modes

All-wheel omnidirectional independent steering vehicle (AWOISV) integrates X-by-wire e-corner modules, enabling multi-steering modes (MSMs), including normal steering mode (NSM), front axle steering mode (FASM), diagonal steering mode (DSM), and zero-radius steering mode (ZSM). In this paper, a novel dynamically switchable torque allocation strategy (TDS) is proposed to enhance control under MSMs. Firstly, based on the Graham Scan algorithm, a longitudinal tire force control envelope (LTFCE) framework is designed to quantify the response ability of longitudinal tire forces to desired force and moment under MSMs. Then, to better estimate the residual capacity of longitudinal tire force, an LSTM-based lateral tire force observer is developed for MSMs, which demonstrates strong performance (RSME <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mo>&lt;</mml:mo> <mml:mn>80</mml:mn> </mml:mrow> </mml:math> N and maximum error <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mo>&lt;</mml:mo> <mml:mn>100</mml:mn> </mml:mrow> </mml:math> N). Furthermore, a TDSs switching matrix is proposed, with TDSs and switch rules developed, considering tire/actuator saturation limits and control objectives under MSMs. Based on results from co-simulation on the Trucksim-MATLAB/Simulink platform and hardware-in-the-loop (HIL) test, it is demonstrated that the proposed method successfully outperforms conventional single-TDS by dynamically switching TDSs under MSMs. Meanwhile, real-time requirement is also satisfied for in-vehicle application.