Control and drive technology in robotics

Lesta has also developed self-learning, anthropomorphic robots, such as the Lebot MV A5 and MV A6. These models are able to record the previously manually taught movements of all axes in real time and then reproduce them precisely in automatic mode. To do this, the painter moves the robot arm with the motors switched off - thanks to a pneumatic compensation system with almost no force wall and virtually weightless. As the pneumatic weight compensation remains active during operation, the motors only have to apply low forces. This reduces the required motor power, its size and the masses to be moved. This in turn benefits the dynamics.

PC-based control makes the difference

For Fabio Ferrario, the continuous and strong growth is a clear indication of the acceptance of the robots: "Our excellent reputation in the mechanical sector has always been well known, but it is above all the exceptional performance of our control systems based on PC-based control that makes the difference." For the development of the automation and control application, Lesta uses TwinCAT 3, whose flexibility and openness as well as the broad product range from Beckhoff have proven to be decisive advantages.

For example, Lesta was able to build on the TwinCAT libraries and combine them with its own expertise, such as the specific coordination of the interpolated movements of the robot axes. "TwinCAT 3 enables us to build an effective and high-performance system based on Beckhoff products, which we can expand at any time with third-party components or additional algorithms if required," emphasizes Fabio Ferrario.

Flowing movements like a painter

Depending on the application, Lesta robots have between five and over a dozen interpolating axes. Fabio Ferrario explains: "The challenge is to perfectly imitate the flowing and smooth movements of a painter with the robots." However, more than precise positioning is required to achieve an even surface coating on the workpieces. This is why the engineers and technicians at Lesta use TwinCAT 3 PLC/NC PTP (TC1250) and TwinCAT NC Camming (TF5050) to optimally simulate the movements of the painter. Manual teaching of the anthromorphic robots is also integrated in TwinCAT. The safety functions are implemented via TwinSAFE. Lesta only uses the .Net framework from Microsoft for visualization. The HMI application runs in parallel to the control task on the same computer, a CX5140 Embedded PC with an Intel Atom quad-core processor. The visualization and control application are linked via the ADS protocol. A CP2915 multi-touch built-in control panel is used as the HMI hardware. To implement the motion sequences generated in TwinCAT, Lesta relies on the AX8000 multi-axis servo system, as it can implement complex motion profiles with high dynamics and at the same time smoothly and precisely. Fabio Ferrario sees further advantages in the compact dimensions and the One Cable Technology (OCT) for connecting the AM8032 and AM8043 servomotors. Both save space in the control cabinet and reduce material costs and installation time. "We usually only need one week from installation to commissioning of a painting station at the customer's premises," says Fabio Ferrario. "The customer can then work autonomously on Fridays."

Scalability as a competitive advantage

Whether a project involves a 6-axis robot or a 12-axis overhead crane variant, a powder coating or a wet painting system, it makes no difference. All variants are based on a master configuration whose functions are activated according to the robot variant. The open and suitably scalable platform from Beckhoff is responsible for this flexibility. Ferrario comments: "There is no doubt that the scalability of our systems is a key USP that sets us apart from our competitors." Paint shops are often connected to the customer network in order to exchange data with other parts of the plant or factory management systems. The availability of the OPC UA communication standard in TwinCAT ensures the corresponding connectivity and makes the Lesta machines Industry 4.0-ready.