US Patent 7806791 Continuously variable transmission and control method thereof

A positional deviation ERRstep of a step motor 27 is calculated on the basis of a reference model step StepMdl, an actual speed ratio-corresponding step Bstep, and an added value obtained by adding together a target deviation GTstep, calculated in accordance with a transmission input torque Ti, and a starting learned value Gstep. When the transmission input torque Ti is large, the target deviation GTstep is increased in accordance with the transmission input torque Ti. A line pressure PL is then controlled on the basis of the positional deviation ERRstep obtained as a result.