Theoretical and experimental analysis of jamming of workpiece in the fixture by using the block and palm study

Jamming of workpiece in the fixture is an unwanted phenomenon which usually occurs during its loading or unloading processes. Investigating the conditions of the jamming occurrence and determining the conditions in which jamming would not occur, are considered as the important steps in the verification stage of the fixture design procedure. In this paper, analytical and experimental analysis is conducted for studying the jamming occurrence conditions using the block and palm study. Theoretical model is established based on the minimum norm principle. The proposed theoretical models in the previous studies which investigated the jamming phenomenon in the quasi-static conditions are also incorporated. Experiments are also designed and implemented for validation of the theoretical predictions. For this purpose, experimental setup is designed and fabricated for the block and palm case study. After measurement of the coefficient of friction between the block, base plate and pal, the jamming-in travel of block (distance in which jamming occurred) is then measured using a rotary encoder and the image processing techniques. The worst-case error equal to 6.8mm (equivalent to 3.8%) is obtained for the jamming-in travel of block between the theoretical predictions and experimental results which indicated the accuracy of the suggested theoretical model.