Fong, K. Au, T. Fu, X.L. Leewe, R. Zheng, Q. JACoW Publishing Geneva, Switzerland 2673-5482 978-3-95450-212-7 10.18429/JACoW-CYCLOTRONS2022-MOPO017 English 99-102 controls cavity ISAC DTL ECR Contribution to a conference proceedings 2023 2023-10 https://doi.org/10.18429/JACoW-CYCLOTRONS2022-MOPO017 https://jacow.org/cyclotrons2022/papers/mopo017.pdf Accelerating RF normal conducting cavities having Quality Factors of over 10³. These cavities must be constantly tuned to maintain resonance for maximum power efficiency. Traditional tuning method uses ’phase comparison method’ by monitoring the phase shift across the input and output of the cavity. This method suffers from phase drift due to diurnal temperature variations. Since 2017, TRIUMF ISAC-1 cavities are tuned using minimal seeking sliding mode controllers, which eliminate effects drift due to temperature changes. As with all extremum seeking algorithm, chattering is invariable present in the system, especially near the end-stage. This paper also includes a new chattering suppression method known as ’skipping surface’, which is slated to be installed in ISAC-1 LLRF upgrade in 2023.