Grasping the need for sensors

Demand for robots equipped with multi function palletising grippers is constantly on the increase in the packaging industry

There are some objects that a human can easily pick up and handle but when you look at the complexity of the operation it is very difficult to replicate with a robot gripper using standard techniques.

We use a combination of observation, imagination and logical design to replicate and enhance the human process.

We like to say that if you can physically get your hands on something then we can find a way to do the same with a robot gripper head." Ian Greenhalgh, Director, Automated Engineering, Lancashire.

"I like to look at the application first hand and to prove the sensor".

"However it is important to realise that solving a sensing application itself is not where our job ends".

"We realise that we must work in partnership with our customers to enhance and add value to their product and in turn benefit the end user" Russell Smith, Regional Sales Manager, Balluff (UK).

Demand for robots equipped with multi function palletising grippers is constantly on the increase in the packaging industry.

Typical palletising grippers can handle crates, cartons, trays, sacks, kegs, pallets, layer pads and individual containers.

Lancashire based specialists, Automated Engineering provide complete bespoke solutions for automated handling applications; encapsulating design concept, development, manufacture, build and commissioning of robotic systems.

It is this complete service allied with the ability to solve difficult tasks through many years experience of different applications that gives Automated Engineering its unique position in the market place.

Director Ian Greenhalgh commented "When we look at an application we like to analyse it from a holistic perspective.

There are some objects that a human can easily pick up and handle but when you look at the complexity of the operation it is very difficult to replicate with a robot gripper using standard techniques.

We use a combination of observation, imagination and logical design to replicate and enhance the human process.

We like to say that if you can physically get your hands on something then we can find a way to do the same with a robot gripper head." With all applications being individual it is important that the positioning and part present sensing feedback employed in the solution is the best available for the particular solution.

With this in mind, Automated Engineering relies exclusively on their established partnership with Balluff .

for advice on sensing requirements.

According to Ian Greenhalgh "Balluff are easy to deal with, their Sales Engineers' product knowledge and more importantly for us, their application expertise is superb.

I have the confidence that given a brief of the application, Balluff will always be available to advise, supply, test and guarantee that we have the best sensors for each individual requirement.

This makes my job easier, we have the confidence to fit and forget" The requirement for multi-functional grippers is growing as they offer savings on capital costs and increase throughput.

A typical packaging/palletising application with a single gripper head not only erects a box but fills it with product, inserts layer sheets and palletises the box.

Some specialist tote bin palletising applications require the robot to stack a layer of 5 totes without gaps by handling one, two or three totes at once and laying them in different orientations to create a layer without any gaps.

All this must be done without entering the inside of the tote itself.

These applications offer a mixture of pneumatic and sophisticated 'finger' clamping systems using features within the product, tote bin or pallet.

A single operation may consist of positioning the gripper head, detection of individual components followed by movement of the relevant actuators on the gripper head for that particular operation with feedback of actuator position.

Positional information is held within the robot, but with so many variables it's advisable to have additional closed loop feedback from positional sensors allowing the gripper head to step onto its new task in the sequence.

Typical operations would require a number of specialist sensors including pneumatic cylinder, inductive proximity, optical proximity, measurement, colour recognition and ultrasonic positional sensors.

Balluff Regional Sales Manager Russell Smith told us "With such a variety of technologies and materials for a single project, it is advisable to take a very hands-on approach to the sensing requirements.

I like to look at the application first hand and to prove the sensor.

However it is important to realise that solving a sensing application itself is not where our job ends.

We realise that we must work in partnership with our customers to enhance and add value to their product and in turn benefit the end user.

For example, with Automated Engineering projects where possible we recommend plug-in sensors linked back to quick change splitter (junction) boxes.

A modular design means not only an increase in build speed for Automated Engineering, but potentially massive saving to the end user in machine down time should any components become damaged.

In addition the end-user benefits by using the integral LED indication for diagnostic purposes, ensuring the maintenance engineer is directed straight to the problem.

Sensor rationalisation is employed, using a single type of sensor for a variety of tasks or to interface with different manufacturer's equipment, this 'one sensor fits all philosophy' helps to reduce the spares requirement and keep down inventory costs" A recent example of this was an application to palletise boxes full of frozen food integrating a vacuum head equipped with suction cups and pneumatically operated vacuum generators onto a Motoman robot base.

The gripper head was designed to accommodate a mixture of Euro pallets and Chep pallets each requiring different layer patterns.

Balluff recommended the versatile 'Optoprox' sensor to handle two very different tasks.

The first ensured the heavy boxes (19 kg each) were present, the Optoprox was used for direct sensing.

The sensor is insensitive to changes in colour or surface shape and texture of the object to be detected and features background suppression and a fixed range.

The second task was for confirmation to the program of robot head position.

The Optoprox sensor was set to repeatably switch at exactly the same distance above the pallet or the present layer of boxes.

This relative positional information can be used to change head speed and trigger other functions such as actuator positioning.

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