02.DELTA ROBOT - Minor-Project-2021-22-AR/Team-08 GitHub Wiki

What is a delta robot?

A delta robot is a type of parallel robot that consists of three arms connected to universal joints at the base. The key design feature is the use of parallelograms in the arms, which maintains the orientation of the end effector, by contrast to Stewart platform that can change the orientation of its end effector.

Delta robots are designed to move at high speeds and perform repetitive tasks quickly and consistently. These robots can replace manual processes where over a 100 parts per minute are being picked, sorted and placed. Delta robots are being used to not only improve consistency and quality of processes where repetitive movements ultimately lead to employee mental fatigue, but they also remove the issue of repetitive motion injuries. The key concept of the delta robot is the use of parallelograms which restrict the movement of the end platform to pure translation, i.e. only movement in the X, Y or Z direction with no rotation.

The robot's base is mounted above the workspace and all the actuators 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 without reductions (direct drive).

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. Having all the arms connected together to the end-effector increases the robot stiffness, but reduces its working volume.

Different versions of delta robot

Delta with 6 degrees of freedom: developed by the Fanuc company, in this robot a serial kinematic with 3 rotational degrees of freedom is placed on the end effector

Delta with 4 degrees of freedom: developed by the Adept company, this robot has 4 parallelogram directly connected to the end-platform instead of having a fourth leg coming in the middle of the end-effector

Pocket Delta: developed by the Swiss company Asyril SA, a 3-axis version of the delta robot adapted for flexible part feeding systems and other high-speed, high-precision applications.

Delta direct drive: a 3 degrees of freedom delta robot having the motor directly connected to the arms. Accelerations can be very high, from 30[10] up to 100 g.

Delta cube: developed by the EPFL university laboratory LSRO, a delta robot built in a monolithic design, having flexure-hinges joints. This robot is adapted for ultra-high-precision applications.

Several "linear delta" arrangements have been developed where the motors drive linear actuators rather than rotating an arm. Such linear delta arrangements can have much larger working volumes than rotational delta arrangements. The majority of delta robots use rotary actuators. Vertical linear actuators have recently been used (using a linear delta design) to produce a novel design of 3D printer. These offer advantages over conventional leadscrew-based 3D printers of quicker access to a larger build volume for a comparable investment in hardware.

Applications

Packing industry

High-precision assembly operations

Medical/Pharmaceutical operations

Food processing

Cosmetics

Soldering

Adhesive dispensing