Special Focus : Robotics
smooth motion of the robot both within the workcell and between production stations. Sensors are fixed on the base of the robot and to other
moving objects in the working area such as workpiece carriers. With this set-up it is no longer necessary to align and position workpieces precisely when they are fed into the workcell.
seconds, for example, 1500 positions must be transferred to the robot controller within a cycle time of two milliseconds. Riesner concludes: “The reliable self-positioning of the mobile robot dispenses with the need for the often highly time-consuming and expensive programming, which frequently makes it unprofitable to use stationary industrial robots, particularly for small batch sizes, high numbers of variants and quick product changes.”
Biomechatronics
Aside from the developments in industrial robots outlined above, it is worth mentioning the project that Festo unveiled at the 2010 Hanover Fair. The Bionic Handling Assistant is not a saleable product, but Festo’s demonstration of a design concept to stimulate dialogue with customers, suppliers and partners. Inspiration for this concept came from elephants’ trunks, and the result is said to be a flexible and safe means of moving objects from one position to another. As well as a flexible arm, the Bionic Handling Assistant has a ‘wrist’ axis with a ball joint, and a gripper with adaptive fingers (Fig. 4). In the event of a collision with an object - including a
Fig. 3. The Alcas project uses Kuka robots for a number of drilling and fastening operations on an aircraft lateral wing box.
Dr Stefan Riesner, the managing director of Robotics Technology Leaders in Munich, comments: “To be able to make robots and manufacturing stations so flexible, a real- time controller is indispensable.” The fast interchange of data between sensors and controller puts the robot in a position to react directly to changes in the work area and to determine its trajectory during movement on the basis of current sensor values. A computer calculates the movement information from the signals and transfers the position data to the robot controller, typically within one to ten milliseconds. For a 15cm curved motion of the robot arm, which takes place in a period of three
human - the Bionic Handling Assistant yields immediately, without modifying its desired overall dynamic behaviour, and then it resumes its operation when the obstruction is removed. Unlike heavy industrial robots, the Bionic Handling Assistant is said to be characterised by an excellent mass-to-payload ratio, provides smooth operating motion with more degrees of freedom, and makes very efficient use of resources. Nobody would suggest that robots are perfect for every
manufacturing operation, as there will always be some for which dedicated special-purpose automation systems are more appropriate, and others for which manual assembly is better suited. However, having made workers redundant during the recession, and faced with competition from low-wage economies, many manufacturers are taking a fresh look at how robotics might help them to meet rising demand. l
Fig. 4. Festo’s Bionic Handling Assistant is a pneumatically actuated ‘elephants’ trunk’ with sufficient compliance that it can be used safely alongside people.
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