日期：2018/02/09 發佈者: 流覽次數：42
The world is not accurate. Humans can handle this. Traditionally, robots require absolute accuracy. In many cases, force/torque sensors can counter this automation challenge; When you mount a sophisticated sensor to a collaborative robot arm, you add a sense of touch. You mimic the human skin and its ability to perceive those touch sensations that feed our brains a wealth of information about the environment around us, such as pressure. For a manufacturing company, six-axis force/torque sensors offer an opportunity to remain competitive on the global scale and make low volume productions cost-effective.
Force/torque sensors add a sense of touch to the robot arm, enabling the robot to pick up delicate items such as fruit without damaging or bruising them. This demo featuring a UR5 robot arm, On Robot gripper, and force/torque sensor from OptoForce was shown at AgriFoodTech Platform Exhibition 2017 by Olmia Robotics BV.
In a global world, manufacturing companies are no longer competing simply at a local level. Large companies move simple production steps to countries with lower labor costs, but according to a recent study by the Institute for Labor Market and Career Research (IAB), small and midsized companies are attempting with increasing frequently to retain their technical workforce and production facilities in their countries of origin. Thus, the pressure to find the optimum price/performance ratio is correspondingly rising and in Europe, an entirely different trend is making this more and more difficult - rising labor costs and a shortage of qualified and able technicians.
Pin insertion is a dexterous task that is usually hard to automate, a force/torque sensor allows the robot to “feel its way” in real time.
Automation of tasks requiring precision – an opportunity for midsized companies
The current advanced level of automation of simple production process that already exists is a step in the right direction. It opens up an opportunity in the world market for midsized companies and offers manufacturing brands an attractive alternative to moving production facilities to low-cost countries. For tasks that require a high level of precision, however, the sensitive touch of the human hand has long been essential and that can be problematic when that is exactly what is in short supply – qualified personnel. At the same time, production environments, as production runs get shorter and shorter, are becoming increasingly less standardized and require more adaptable and more intelligent robotic systems.
Force/torque sensors close this gap, because they give industrial robots a sense of touch. Robotic arms equipped with haptic sensors are capable of perceiving the slightest resistance or pressure and that means that robots are no longer limited to moving between preprogrammed points, but can adapt to their movements and environment in real time instead.
For example, if a packaging application is required so that standard sized products of exactly the same size can be placed into an equally standard sized carton, even if the carton is not well positioned, then it is enough to preprogram the corresponding positions and movements into the robot, which then carries out the exact same sequence over and over again. However, this changes drastically when the task is no longer to package standardized products but rather those of different customized sizes – which is increasingly the case. This cannot be done with preprogrammed positions.
The capability of haptic sensors to precisely measure force, however, allows robots to perceive even the slightest resistance in each work step, giving them the sense of touch required to adapt its movements in real time – thereby making it ideal for running applications such as stacking and packing objects or products with different dimensions and weights. This means that short production runs can be easily automated without the need to reprogram the robot every time the size of the product packaging changes.
The programming interface of OptoForce’s force/torque sensor has been integrated directly onto the UR robots’ teach pendant through the UR+ platform. The integration means that users can program both robot arm and sensor through the same touch screen. The software package comes with preprogrammed standard industrial applications which immensely shorten and simplify integration time. Examples of prepackaged applications can include inserting plug connectors, polishing applications or palletization. The applications are ready to operate within just 15 minutes and don’t require extensive programming knowledge or expensive third-party expertise.
Force/torque sensors therefore make it possible to use industrial robots for production tasks for which the sensitivity of human hands has always been essential, helping companies to increase their efficiency and productivity even in these areas – a central factor in future readiness for both global and local competition. For companies, this is one way to react to increasing demands without significant added costs.
Better performance even in already automated processes
Six-axis force/torque sensors, however, don’t simply contribute to expanding automation possibilities to those processes that couldn’t be automated before. They also help to improve performance in processes that are already automated. A robotic arm navigating rigidly between predetermined waypoints is incapable of detecting and reacting appropriately to any irregularities in the workpiece or in the surface to be processed. It always performs the same movement, no matter what.
The result can be manufacturing errors which persist throughout the rest of the value creation chain – until the end customer complains about the product. In the worst case, there could even be production downtime, a disproportionately costly situation for any company and one that should be avoided at any cost.
These scenarios can be avoided using haptic sensors, which guarantee precision and consistent quality in the manufacturing process, preventing costly errors, wastage of materials and defective products.
Palletizing is another task often automated with robots that benefit from having sensor feedback on how exactly to place the palletized part
Shorter integration time for robotic systems
As with any other manufacturing technology, one factor that is always of central importance in the introduction of a robotic system - integration time. In addition to the cost of the implementation and the increased efficiency achieved, this is a deciding factor when defining the ROI (return on investment) and therefore the measure of success the company can expect using the technology.
The more adaptable and flexible a robotic system is, the more easily it can be integrated and the faster it can be pay for itself and thereafter earn profits. The sense of touch obtained by using six-axis force/torque sensors represents a significant gain in adaptability for robotic systems – which means that more production lines can be automated in the same time. The price of the sensors is usually not an issue in comparison with the benefits obtained.
In this application, inserting a battery into a cell phone, precise insertion processes can be automated with small counter forces, even with forces under 10 Newtons.
In conclusion, using force/torque sensors to provide robotic arms with the sense of touch greatly benefits a company in many ways. They can ultimately achieve higher levels of competitiveness thanks to this technology through automating precise processes that before required human dexterity to carry out, improving the performance of already automated tasks, and reducing the time to integrate robotic systems through increased flexibility. All of which lead in turn to a faster return on investment and a lowering of ownership costs.