Study on the collision-mechanical properties of tomatoes gripped by harvesting robot fingers

The data of collision-mechanical property of tomatoes gripped by robot fingers are important for the gripping control of tomato harvesting robot. In the study, tests of controlling the fingers to grip tomatoes were conducted to ascertain the effects of input current, motor speed and impact positions on the impact force of fingers and maximum deformation of tomatoes. The input current of the motor ranged from 1200 to 2100 mA, the motor speed from 25 to 3000 rpm and the three impact positions as follows, 1 (radial arm), 2 (sloping at an angle of 22.5 to the radial arm) and 3 (sloping at an angle of 45 to the radial arm). The results shown that under the condition of the same motor speed and input current, the peak impact force on the radial arm, compared with other impact positions, was maximum, the deformation of tomato was the smallest and the degree of mechanical damage was the lowest too. Under different speed and input current conditions, when the fingers grip the tomato on the radial arm, the peak force of fingers and the maximum deformation of tomatoes were highly influenced by the motor speed and input current, especially the input current. The peak impact force and the maximum deformation of the tomato increased respectively with increase in the motor speed and input current and these followed cubic polynomial regression equations.