Abstract: The aim of this study is to systematically reveal the differences in the biomechanics of 16 hand regions related to bionic picking of tomatoes. The biomechanical properties (peak loading force, elastic coefficient, maximum percentage deformation and interaction contact mechanics between human hand and tomato fruit) of each hand region were experimentally measured and covariance analyzed. The results revealed that there were significant variations in the assessed biomechanical properties between the 16 hand regions (p?<?0.05). The maximum pain force threshold (peak loading force in I2 region) was 5.11 times higher than the minimum pain force threshold (in Th1 region). It was found that each hand region in its normal direction can elastically deform by at least 15.30%. The elastic coefficient of the 16 hand regions ranged from 0.22 to 2.29 N mm?1. The interaction contact force acting on the fruit surface was affected by the selected human factors and fruit features. The obtained covariance models can quantitatively predict all of the above biomechanical properties of 16 hand regions. The findings were closely related to hand grasping performance during tomato picking, such as soft contact, surface interaction, stable and dexterous grasping, provided a foundation for developing a high-performance tomato-picking bionic robotic hand.

Key words: Human hand , · Bionic grasping , · Elastic deformation , · Tomato picking , · Robotic hand