Comparative study on resistance and displacement based adaptive output tracking control strategies for resistance spot welding

•Two types of abnormal welding condition: edge welding (EW) and initial gap (IG), are taken into consideration to verify the validity of resistance and displacement based adaptive output tracking control strategies.•Even if the dynamic resistance or electrode displacement signal of the weld under EW and IG conditions coincides with that of the standard condition, their weld properties are still different.•The use of resistance-based tracking control strategy would reduce the welding current under EW and IG conditions, and lead to a decline of the nugget size and tensile-shear strength.•The displacement-based tracking control strategy works well in EW and IG conditions of slight level and enhances the nugget size and tensile-shear strength. However, it may raise the expulsion risk when the disturbance is too severe.