A study on road slope estimation for automatic transmission control

We studied two algorithms for road slope estimation to avoid needless shifting when vehicles with automatic transmissions are running uphill and downhill. One algorithm makes an estimation using a longitudinal acceleration sensor and the other makes an estimation using estimated vehicle output torque. The former is expected to estimate road slope more accurately than the latter, but the former is more expensive because an additional acceleration sensor is needed. The two algorithms were implemented on the transmission control unit and compared experimentally. We found the latter could estimate road slope accurately enough to avoid needless shifting. (C) 2000 Society of Automotive Engineers of Japan, Inc. and Elsevier Science B.V. All rights reserved.