Latest cobot aims to offer 'next level' in collaborative automation

Mitsubishi Electric has unveiled the first member of its new MELFA Assista series of collaborative robots, or cobots. These next-generation machines are designed to offer maximum safety and durability combined with ease of use and programming, while maintaining very high positional repeatability.

The new RV-5AS-D-S99 MELFA Assista collaborative robot allows companies to automate a broad range of production line processes: from machine loading, device assembly, kitting and un-kitting of parts to testing and inspection.

The challenge for a true cobot is to remain helpful while allowing a high degree of autonomous interaction with a human operator. Unlike an assistive arm used frequently for manipulation of heavy objects on car assembly lines for example, or an industrial robot that works at high speeds but merely slows down or stops in the presence of a human operative, a cobot has to be interactive.

Teaching a robot how to do tasks which help a human operative has to happen quickly and intuitively, otherwise the advantage is almost certainly lost. Which is why the new example from Mitsubishi Electric can be programmed via a PC, touch screen HMI, or simply by hitting the ‘save’ button and guiding and teaching the arm through the required sequence of movements.

Adjusting the sequence or the positions held is just as quick and easy which makes the robot an adaptable, easy to teach assistant that is totally consistent with its repeatability. This makes it ideal for complex and / or delicate assembly, work holding or pick and place tasks where the operator will have a preferred way of working and will benefit from the robot’s assistance to complete the task or sequence of operations. This is particularly true of high-value manufacturing such as jewellery, electronics and life-science applications.

Safe and sound

A sophisticated solution that guarantees operational safety alongside its flexibility and high positional accuracy was the aim for the design team that developed the RV Series Assista model. Payloads are consequentially relatively low as the arm is force limited for safety. It also has to be very responsive in terms of touch sensitivity and this clearly limits overall speed. Positioning accuracy however is comparable with industrial robots.

The safety features and technical specifications are in accordance with ISO/TS 15066 guidelines on “Robots and robotic devices — Collaborative robots”. The six-axis articulated arm features a slim profile and good reach from a small footprint, making it ideal for deployment as a desk-top unit or within the confines of an individual work cell.

Where the innovative cobot stands out from other existing collaborative automation solutions is in its positional repeatability. While other collaborative robots feature positioning accuracy repeatability values of ±1 mm, the latest Mitsubishi Electric product offers positioning accuracies as low as ±0.02 mm. This is comparable with high-performance industrial robots. The increased accuracy opens up a wider range of applications dealing with more delicate operations and smaller parts.

The MELFA Assista also uses some of the design principles of Mitsubishi Electric’s MELFA industrial robots in order to maximise durability and reliability. In fact, the service life of this new cobot is in line with standard MELFA industrial robots, some of which have been running smoothly for over 30 years. As a result, businesses can expect minimal downtime, less frequent maintenance tasks and lower operating costs.

Lighting the way

When it comes to ease of use, operators will benefit from some new features such as a six-colour LED ring, mounted around the robot 'forearm', to provide quick visual recognition of the arm’s current status. Each colour identifies a different mode of operation, alarms or faults.

This feature sits next to the keypad that provides an intuitive interface to ‘teach’ the robot a task to perform, as well as to start and stop the robot or reset errors. In ‘direct control’ mode the operator manipulates the robot into position by hand and with controlled force. This position can then be stored and added to the existing motion sequence or attributed to an individual command without the need to open the programming tools.

In addition, it is possible to programme motion sequences via a new programming environment, called RT Visual that can run on conventional PC operating systems. As the name suggests, programming is designed to be graphical and intuitive. Operators can select drag and drop motion icons to define the intended movements, as well as simulate operations before having the robot perform them.

Barry Weller, product manager at Mitsubishi Electric, commented: “Accuracy and ease of use have taken a significant step forward with this product, which is the culmination of technical development as well as many hours of field testing and user feedback. I believe our latest MELFA Assista collaborative robot opens up new opportunities for cobots in a number of sectors.”

The new RV-5AS-D-S99 MELFA Assista collaborative robot is due for commercial release in the UK during the first quarter of 2020.

See how Mitsubishi Electric is able to respond to today’s automation demands by visiting

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