A method of cleaning dirty crockery, the method comprising: supplying dirty crockery; detecting gripping positions of items of the dirty crockery by an electronic vision system; gripping an item of crockery at its detected gripping position by a gripper member (102, 104) of a manipulator, the gripper member (102, 104) comprising a gripper body (130, 170), and a pair of fingers (132a, 132b, 172a, 172b) extending from the gripper body (130, 170), each finger having an end carrying a clamping member (136a, 136b, 176a, 176b) for contacting the item of crockery, the fingers (132a, 132b, 172a, 172b) being moved towards one another for gripping the item of crockery; rotating the clamping members (136a, 136b, 176a, 176b) around an axis parallel to a line connecting the ends of the fingers (132a, 132b, 172a, 172b) for changing the orientation of the item of crockery; placing the gripped item of crockery in a predetermined position in a predetermined basket by the manipulator; feeding the basket into a washing machine; and washing the crockery by the washing machine, wherein the electronic vision system is configured for: taking an image of the item of crockery by at least one camera (28, 47) having a predetermined position; analyzing the image by a processor; and storing dimensional data of different types of crockery in a memory coupled to the processor, the dimensional data comprising diameters of circular edges of the different types of crockery; wherein the processor is configured for: detecting a circular or elliptical shape in the image; determining a diameter corresponding to the circular or elliptical shape in the image; comparing the diameter corresponding to the circular or elliptical shape in the image with the stored diameters of circular edges of the different types of crockery; and if the diameter corresponding to the circular or elliptical shape in the image is substantially equal to a stored diameter of a circular edge of a particular type of crockery, then identifying the circular or elliptical shape in the image as the circular edge of the particular type of crockery. supplying dirty crockery; detecting gripping positions of items of the dirty crockery by an electronic vision system; gripping an item of crockery at its detected gripping position by a gripper member (102, 104) of a manipulator, the gripper member (102, 104) comprising a gripper body (130, 170), and a pair of fingers (132a, 132b, 172a, 172b) extending from the gripper body (130, 170), each finger having an end carrying a clamping member (136a, 136b, 176a, 176b) for contacting the item of crockery, the fingers (132a, 132b, 172a, 172b) being moved towards one another for gripping the item of crockery; rotating the clamping members (136a, 136b, 176a, 176b) around an axis parallel to a line connecting the ends of the fingers (132a, 132b, 172a, 172b) for changing the orientation of the item of crockery; placing the gripped item of crockery in a predetermined position in a predetermined basket by the manipulator; feeding the basket into a washing machine; and washing the crockery by the washing machine, taking an image of the item of crockery by at least one camera (28, 47) having a predetermined position; analyzing the image by a processor; and storing dimensional data of different types of crockery in a memory coupled to the processor, the dimensional data comprising diameters of circular edges of the different types of crockery; detecting a circular or elliptical shape in the image; determining a diameter corresponding to the circular or elliptical shape in the image; comparing the diameter corresponding to the circular or elliptical shape in the image with the stored diameters of circular edges of the different types of crockery; and if the diameter corresponding to the circular or elliptical shape in the image is substantially equal to a stored diameter of a circular edge of a particular type of crockery, then identifying the circular or elliptical shape in the image as the circular edge of the particular type of crockery.