## 5 Conclusions  
In this study, a novel differential called motor-modulated lateral torque vectoring differential, MLTD, is proposed. The corresponding architecture and kinematic characteristics are described, specifically including the principle for lateral torque vectoring control using an auxiliary motor, DM. A steady-state vehicle dynamic model is developed to evaluate the optimal corning performance due to torque vectoring, which can be used to determine a suitable power capacity for DM. Then, a design case of a front-wheel-drive electric vehicle with MLTD is conducted, consisting of three stages of evaluation, i.e., cornering performance, driving performance, and energy efficiency performance. Based on the above analysis, the following conclusions can be drawn:  
1. MLTD, consisting of one single-pinion planetary gearset, one double-pinion planetary gearset, one traction motor, one distributing motor, and one reduction gearest, is a novel differential capable of performing lateral torque vectoring by electronic torque control of the distributing motor. 2. The proposed algorithm of the vehicle dynamic model show that an optimal lateral torque vectoring ratio can be obtained at a given driving speed and longitudinal acceleration, and is nearly linear proportional to the adhesion coefficient of tire. Figure 26: Variations in \(E_{c}\) at right turn and of a baseline case vs. \(\epsilon_{r}\) at \(v=60\) km/h. Figure 25: Variations in \(E_{c}\) vs. \(v\) under cruise driving. 3. Reducing the vehicle mass for improving energy efficiency of electric vehicle will undesirably degrade the cornering performance and can be compensated by applying lateral torque vectoring. 4. The sizing for distributing motor is realized by combining the analysis of optimal cornering performance with that of the driving performance. In this design case, the power capacity of the distributing motor is only 7.5% that of the traction motor, offering a desirably high cost/performance ratio. 5. The energy efficiencies of MLTD at left turn are very close to those at straight driving in the mid/high speed range, while those at right turn are still about 95% lower mainly due to unavoidable loss of power recirculation. 6. The energy deficiencies at right turn may be paid off by moderately cutting down the rolling resistance of tire by 11.1%, e.g., reducing vehicle mass of 1600 kg by about 200 kg, with the superior cornering performances still held using lateral torque vectoring. 7. Conclusively, the newly proposed MLTD possesses greater potential to enhance energy efficiency and driving range of electric vehicles without trading off against its desirable cornering performance and safe handling, and is thus worthy of further development. Future research will focus on simulating and analyzing the effects of vehicle speed, steering behavior, and control strategies of torque vectoring on the energy efficiency and corning performance based on driving cycles with cornering pattern. Then, prototype of MLTD will be constructed to verify its functionality of motor-modulated torque vectoring, and hardware-in-the-loop simulations will be carried out to find out the optimal torque control strategy. Finally, implementing MLTD on real cars is highly expected. Conceptualization, C.-T.C. and H.-Y.T. ; methodology, C.-T.C. ; software, C.-T.C. and H.-Y.T. ; validation, C.-T.C. and H.-Y.T. ; formal analysis, C.-T.C. ; investigation, C.-T.C. and H.-Y.T. ; resources, H.-Y.T. ; data curation, C.-T.C. ; writing--original draft preparation, C.-T.C. ; writing--review and editing, H.-Y.T. ; visualization, C.-T.C. and H.-Y.T. ; supervision, C.-T.C. ; project administration, H.-Y.T. ; funding acquisition, H.-Y.T. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Science and Technology Council, Taiwan, R.O.C. ; grant number NSTC 112-2221-E-150-036-. Not applicable.