Pick and Place
The Delta robot is a parallel robot that consists of multiple kinematic chains interconnecting the base with the end-effector and is often used to handle small products such as confectionery but larger items can also be accommodated. One recently developed pick and place system saw the gripper making use of the rotation axis of the robot to affect pitch changes on-the-fly as the robot moves from the pick position to the placement position, where products are deposited side by side and without any gaps.
The key concept of the Delta robot is the use of parallelograms. These parallelograms restrict the movement of the end platform to pure translation (only movement in the X, Y or Z direction). The robot’s base is mounted above the workspace and all the acutators are located on it. From the base, three middle jointed arms extend. The ends of these arms are connected to a small triangular platform. Actuation of the input links will move the triangular platform along the X, Y or Z direction. Actuation can be done with linear or rotational actuators, with or withour reductions. Since the actuators are all located in the base, the arms can be made of a light composite material. As a result of this, the moving parts of the Delta robot have a small inertia. This allows for very high speed and high accelerations.
Other versions of the delta robot have been developed such as Delta with 6 degrees of freedom and on the end effector is placed a serial kinematic of 3 rotational degrees of freedom.
To enhance pick & place systems, vision solutions can be used, installations can identify a variety of object characteristics in preparation for picking, which include position, colour, size, product, weight and even orientation.
The design of the end effector is one of the most important elements of any robot system. Although there are many different types available, the most commonly used gripper are finger grippers. These will generally have two opposing fingers or three fingers like a lathe chuck. The fingers are driven together such that once gripped, any part is centred in the gripper. Two finger grippers can be further split into parallel motion or angular motion fingers. Where flexible or fragile objects are being handled, the use of either vacuum or magnetic grippers is more suitable.