Slip speed monitoring of a multi-speed planetary transmission

A method for controlling, using a planetary transmission controller, a planetary transmission having a plurality of planetary gearsets and a plurality of selective couplers, the planetary transmission being driven by a prime mover at an input of the planetary transmission and driving a driven component at an output of the planetary transmission, the plurality of selective couplers are selectively engaged in a plurality of combinations to establish a plurality of speed ratios between the input of the planetary transmission and the output of the planetary transmission, the method comprising:

• receiving a first characteristic indicative of a first speed of a first component of the transmission;
• receiving a second characteristic indicative of a second speed of a second component of the transmission;
• across a plurality of shift events of the plurality of selective couplers, estimate a slip speed of at least a subset of the plurality of selective couplers based on the first characteristic and the second characteristic;
• capturing a maximum slip speed for the subset of the plurality of selective couplers during a shift event of the plurality of shift events to monitor a health condition of the subset of selective couplers;
• and
• wherein the planetary transmission controller includes a calibration mode for each shift type and a normal mode for each shift type, where each shift type includes a change in state of the plurality of selective couplers from one of the plurality of speed ratios to another of the plurality of speed ratios, wherein in the calibration mode for each shift type, increasing a shift count by one for each shift event of the shift type, and determining an average maximum slip speed for each selective coupler for each shift event in the calibration mode.

A planetary transmission comprising:

• at least one stationary member;
• an input member rotatable relative to the at least one stationary member;
• a plurality of planetary gearsets operatively coupled to the input member, each of the plurality of planetary gearsets including a first gearset component, a second gearset component rotatable relative to the first gearset component, and a third gearset component rotatable relative to the second gearset component;
• an output member operatively coupled to the input member through the plurality of planetary gearsets and rotatable relative to the at least one stationary member;
• a plurality of selective couplers, wherein the plurality of selective couplers includes a first number of clutches and a second number of brakes, the plurality of selective couplers are selectively engaged in a plurality of combinations to establish a plurality of speed ratios between the input of the planetary transmission and the output of the planetary transmission;
• a plurality of sensors including a first sensor of the plurality of sensors positioned to monitor a characteristic indicative of an input speed of the input member, a second sensor of the plurality of sensors positioned to monitor a characteristic indicative of an output speed of the output member, and a third sensor of the plurality of sensors positioned to monitor a characteristic indicative of a speed of an interconnector of the planetary transmission, the interconnector may rotate independent of the input member of the planetary transmission and may rotate independent of the output member of the planetary transmission;
• a planetary transmission controller configured to determine slip speed of each of the subset of the plurality of selective couplers based on data received from the plurality of sensors, the planetary transmission controller further configured to:
• capture a maximum slip speed for the subset of the plurality of selective couplers during a shift event of the plurality of shift events to monitor a health condition of the subset of selective couplers;
• and
• monitor excursions in a health condition of any one of the subset of the plurality of selective couplers during the shift event based on maximum slip speed of the respective any one of the subset of the plurality of selective couplers.