Method using torque mode of motor for the shift of two-speed planetary CLAMT in bilateral electric drive tracked vehicle

For the shift control of clutchless automotive manual transmission (CLAMT) in electric vehicle, great difficulty is caused by the high level of precision and rapidity requirements of the speed and mode response of motor as well as the position response of gearshift sleeve, especially when confronted with off-road environment. To overcome the difficulty and achieve fast shift, a practical control method is proposed and applied to two-speed planetary CLAMT for off-road tracked vehicle with bilateral electric drive system, wire control system and unmanned driving purpose. In shift process, the method lets motor be controlled by applying torque mode and constant torque during active speed adjusting phase, lets gear engaging phase be started at the time when transmission ratio is regulated beyond a certain value close to target gear ratio – that is, at the time when the approach of synchronized state is achieved, lets synchronizer make a help for precise gear synchronization. Theoretical analysis of gear synchronization process is carried out. By increasing the level of motor torque, the duration of active speed adjusting phase can be obviously shortened. With the approach of synchronized state judged by using transmission ratio margin of small fixed positive value for reference, gear engaging phase can be achieved quickly. Off-road experiments show good performance of the shift control method. Experimental results and phenomena are discussed in detail for further and better understanding of real shift process.