May 2019

n TECHNOLOGY May 2019 www.drivesncontrols.com 20 RESEARCHERS INthe US have developed a robotic gripper that’s soft and strong. The cone-shaped structure, called Magic Ball, collapses in on objects and can pick up items that are 100 times its weight. The gripper can grasp objects ranging from soup cans and wine glasses, to single florets of broccoli. “One of my moonshots is to create a robot that can automatically pack groceries for you,” says professor Daniela Rus, director of MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL), which developed the gripper in conjunction with Harvard’s School of Engineering and Wyss Institute for Biologically Inspired Engineering. “Previous approaches to the packing problem could only handle very limited classes of objects – objects that are very light or that conform to shapes such as boxes and cylinders – but with the Magic Ball gripper system, we’ve shown that we can do pick-and-place tasks for a large variety of items ranging from wine bottles to broccoli, grapes and eggs,” Rus explains. “In other words, objects that are heavy and objects that are light. Objects that are delicate, or sturdy, or that have regular or free-form shapes.” The hollow, vacuum-powered gripper surrounds an object to pick it up. It has three parts: an origami-based skeleton; an airtight skin to encase the structure; and a connector. The team created it using a special heat-shrinking plastic that folds itself at high temperatures. The skeleton is covered either by a rubber balloon or a thin sheet of fabric. In tests, the developers found that the gripper could grasp and lift objects up to 70% of its diameter, and could pick up and hold soft foods without damaging them. It could also pick up bottles weighing 1.8kg. “Companies like Amazon and JD want to be able to pick up a wider array of delicate or irregular-shaped objects, but can’t with finger-based and suction-cup grippers,” says Shuguang Li, a post-doctoral student at MIT CSAIL and Harvard’s John A. Paulson School of Engineering and Applied Sciences. “Suction cups can’t pick up anything with holes – and they’d need something much stronger than a soft-finger-based gripper.” The new gripper currently works best with cylindrical shapes such as bottles or cans. It is more difficult for it to grasp flat objects such as books. “One of the key features of this approach to manipulator construction is its simplicity,”says RobertWood, a professor at Harvard’s School of Engineering andWyss Institute for Biologically Inspired Engineering.“The materials and fabrication strategies used allow us to rapidly prototype new grippers, customised to object or environment as needed.”  In the future, the team hopes to add computer vision that would allow the gripper to “see” and to grasp specific parts of objects from any angle or orientation. Conventional rigid grippers tend to work best in structured environments with predefined shapes and locations, and typically can’t cope with uncertainties in placement or form. In recent years, roboticists have been tackling this problem by making grippers out of soft, flexible materials, such as rubber. This pliability lets them pick up a variety of objects, but they usually cannot handle large or heavy items. Soft robotic fingers powered by compressed air are usually not strong enough to pick up heavy objects. Novel designs such as ball-shaped grippers can handle a wider range of objects than fingers, but are limited in the angles at which they can operate. Soft robotic gripper can lift items that are 100 times its own weight The soft robotic gripper can pick up delicate items weighing much more than itself YASKAWA HAS INTRODUCED a series of AC microdrives which, it claims, can achieve energy savings that are up to 6% higher than other drives. The GA500 drives span ratings from 0.2–30kW, and can be used to control permanent magnet and synchronous reluctance motors, as well as induction machines, without the need for comprehensive tuning. Yaskawa says that when operating induction motors, the drives can boost efficiencies by up to 6% at 20% speed, compared to other drives. For permanent magnet motors, the claimed improvement is up to 2%. The drives offer: built-in EMC filters; a dual-channel STO safety function (SIL 3/PL e); the ability to network up to five drives using an optional fieldbus card; an embedded brake chopper for regenerative braking; a 590Hz output frequency; and apps for mobile devices. A robust design allows the drives to operate at altitudes of up to 4km and in temperatures up to 60ºC. Coated circuit boards protect against dust and mist. The drives’ temperature- controlled fans run only when needed, reducing the potential for contamination and extending service intervals. An internal 24V DC power supply can deliver an extra 150mA for use with external sensors, eliminating the need for separate supplies. Normal duty rating allows users to run one size larger motor in variable-torque applications. A bright LED display and tactile keypad ensure intuitive navigation through the drives’menus, which are arranged and named as on other Yaskawa drives, minimising the need for re-training. An embedded programming environment allows drive functions to be customised and can replace the need for external controllers. A USB port supports connections to PCs or mobile devices for programming, monitoring or troubleshooting. Easy-access terminals ensure quick connection of mains and motor cables without needing to remove any covers. Screw-less control terminals result in reliable connections that do not need to be re-tightened. www.yaskawa.eu.com AC microdrives promise up to 6%more energy saving