LEGO robotic cell model for ABB press automation

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LEGO robotic cell model for ABB press automation

LEGO robotic cell model for ABB press automation

In early 2016, the Press Automation division of ABB Robotics (Sabadell, Spain) contacted me to realize a set of LEGO modules for a robotic cell model to be showed during an upcoming series of events and fairs in United States and Europe. The same model can also be used for robotic cell training. The project was part of the market launch of a new ABB software package, aimed to simplify the setup of robotic stamping cells, reducing the setup time from days to hours. After a feasibility study, ABB shared all the details about the project, in particular to interface teh actual ABB robot controller with custom-made electronic boards to drive the LEGO motors.
I built two identical sets of LEGO modules, one for the United States, the other to remain in Europe. The robotic cells were shown during ABB Value Provider Conferences, on 8-9 June 2016 in Atlanta (Georgia, USA) and on 28 June 2016 in Stockholm (Sweden). The twin cells will be used by ABB for training purposes in the future.

Metal stamping process simulation

This robotic cell model simulates, in a small scale, the automatic process of stamping metal with a large hydraulic press. A real metal stamping cycle includes the following steps:

  1. the operator loads a blank metal sheet on a turntable that separates him from the dangerous inner part of the cell;
  2. the operator presses a button, the turntable rotates by half turn to bring the blank part inside the cell;
  3. the ABB robot arm is authorized to pick the blank part from the turntable, and drop it on the tilted centering table;
  4. the blank part slides down to the bottom corner of this table, so it is aligned automatically by gravity;
  5. the robot arm, equipped with a dual vacuum picker, picks up the aligned blank part, removes a finished part from the C-type press, and simultaneously drops the blank part into the press bed;
  6. once the robot arm exits the press working area, the PLC authorizes the press to execute its stamping cycle, while the robot drops the finished part on a conveyor, which brings the part out of the cell;
  7. the part that has just been stamped remains inside the press until the next cycle of the cell, triggered by the operator with a button press before.

What is a robotic cell?

A robot manipulator and a collection of machines or peripherals is referred to as a robotic workcell, or simply a robotic cell. A typical cell might contain a parts feeder, a molding/stamping machine, and a robot. The various machines are integrated and controlled by a single computer or PLC (Programmable Logic Controller). In this case, the peripherals of the robotic cell are made with LEGO bricks, and controlled by custom electronic boards, while the robot is a real ABB IRB 1200-7/0.7 arm.

The LEGO devices of the robotic cell

The set of LEGO modules includes four devices:

  • A turntable of a 40cm diameter with a see-though wall in the middle. The turntable can rotate by half turn back and forth.
  • A centering table which is a passive tilted table (with no actuators or sensors) that allows the blank parts to be squared-up by sliding down to the bottom corner of the table edge.
  • A C-type press that can exert the enough force to stamp a message on a blank visit card. The press incorporates a self-inking stamp with weakened springs, equipped with a custom-made matrix. The press ram moves up and down smoothly thanks to a position, speed and acceleration controller that drives the LEGO MINDSTORMS servomotors.
  • A linear conveyor that carries the finished cards out of the cell, into a basket.

In real-sized robotic stamping cells, the robots and the metal parts to be moved are big and heavy, so there’s a potential hazard for humans. The press itself can exert tons of pressure. Instead, all the LEGO devices of the robotic cell model are inherently safe, the torque of the motors is low, and the press “tonnage” is just few kilograms. This makes this robotic cell model ideal for safe training of operators.

Design requirements

In the past, in the field of industrial process simulation, I realized LEGO car factories with many robots and moving parts, and complex software behind their smooth operation. Compared to those projects, the movements of these LEGO devices is quite simple: turn clockwise/counterclockwise, go down and up again, turn for a certain amount of time. The design requirements that made this work challenging and interesting are that the various modules had to be interfaced with an industrial PLC, and that we could swap them with real peripherals in a plug-and-play manner, being them compatible at electric level and at hardware connector level. Also, the various devices were designed to look uniform in shape and color scheme with the real ABB machines. In particular, the key specification for the press was that it should look “sexy”, so I designed it as curvy as possible. 

Using LEGO models to simulate real industrial processes

There is an increasing number of companies that need LEGO models to simulate industrial processes, like manufacturing lines, automation systems, robotic cells.
Developing LEGO industrial simulations require very specialized skills, making this a very specialized niche business, with respect to the general LEGO static model design.
The benefits of having a desktop working LEGO model that represents a real industrial process are many:

  • its small scale and lightweight make it portable, luggage-proof, and easy to store away;
  • the LEGO building system, integrated with high-precision servomotors and custom electronics, allow to make realistic and detailed working mechanisms;
  • the models are highly customizable, easy to maintain and to tweak;
  • the models are intrinsically less expensive than real industrial plants, making them ideal for training of specialized operators, and R&D engineers.