Variator characterization for feed forward torque control

A method of providing torque control operation in a transmission having a variable displacement variator having a hydraulic actuator for varying displacement, and having an output, the variator further having an internal circuit pressure, the method comprising:

• commanding a first hydraulic pressure sweep to the hydraulic actuator while imposing substantially zero torque on the variator output and recording a first corresponding sweep of motor speed ratio of the variator during application of the first hydraulic pressure sweep;
• commanding a second hydraulic pressure sweep to the hydraulic actuator while preventing the variator output from deviating from a fixed output speed regardless of circuit pressure and recording a second corresponding sweep of variator output torque during application of the second hydraulic pressure sweep;
• and
• constructing a map relating motor torque, motor speed ratio, and actuator pressure by scaling the first corresponding sweep of motor speed ratios and the second corresponding sweep of variator output torque.

A controller for providing torque control operation for a transmission having a variable displacement variator with a hydraulic actuator for varying displacement, and having a pump and a motor having an output, the controller comprising:

• one or more inputs to receive data corresponding to a variator motor speed, a variator circuit pressure and a pump speed;
• one or more outputs to write data to memory;
• a processor for executing computer-readable instructions from a non-transitory computer-readable medium;
• and
• a set of computer-readable instructions stored on the non-transitory computer-readable medium, the instructions including instructions for commanding a first hydraulic pressure sweep to the hydraulic actuator while imposing substantially zero torque on the variator output while recording a first corresponding sweep of motor speed ratio of the variator and for commanding a second hydraulic pressure sweep to the hydraulic actuator while preventing the variator output from deviating from a fixed output speed while recording a second corresponding sweep of variator output torque, and populating a map relating motor torque, motor speed ratio, and actuator pressure by scaling the recorded data.