With the recent demise of Rethink Robotics, there were dozens of testimonials that the company revolutionized industrial robotics and kickstarted the collaborative robotics trend. There is no doubt that Baxter and Sawyer were truly innovative and more sophisticated than the average industrial robot. They were also safer than most other cobots, though at the expense of precision. So was Rethink Robotics the pioneer of collaborative robots?
If you drive a car, it makes little difference what brand it is: all cars are driven in essentially the same way. The same applies to computers. If you have a Windows PC, the user interfaces won’t be affected by your computer hardware. This is definitely not the case for industrial robots.
The way you program an industrial robot strongly depends on the robot brand. You might think that a robot program looks like C++ or Visual Basic. The truth is that some robots are still programmed in assembler-like languages.
Many researchers think that robot calibration is an issue that has been successfully resolved decades ago, but they are wrong. While the underlying theory is well established, its practical application continues to be in its infancy. This is the first of a series of posts that will provide evidence that it is still very hard for a user to get an accurate industrial robot. So hard indeed that a company in New Zealand didn’t hesitate to ask one of my postdocs fly in for help.
ABB finally announced today that it acquired Germany-based Gomtec, in order “to expand its offering in the field of collaborative robots.” The acquisition actually took place in February this year. As Gomtec’s web site went offline yesterday, and journalists simply retransmit ABB’s press release, many are certainly wondering who is Gomtec?
All the stars were aligned for Automate 2015 to be a very exciting industrial robot show. Exhibit space was 80% larger than in 2013. Universal Robots was to showcase its new UR3 collaborative robot. And of course, Rethink Robotics was supposed to unveil its one-armed cobot, Sawyer. But it didn’t. And this probably darkened my perception of the show. (The fact that my first flight was delayed didn’t help either.)
Six months ago, after the publication of our revelatory feature article regarding the safety of Universal Robots’ UR5 collaborative robot arm, Precise Automation expressed their interest to have their one-of-a-kind PF400 collaborative SCARA robot undergo a similar study in our lab. The company claims that the PF400 is “intrinsically safe since all of the forces generated by its axes are limited so that the robot cannot hurt a user even if it collides with them at full speed.” I asked one of our undergraduate students to test the demo unit that we received on loan. So does he think we should leave the PF400 fenceless?
Position repeatability is one of the most important performance criteria of industrial robots. The ISO 9283:1998 norm defines it as the “closeness of agreement between the attained [positions] after n repeat visits to the same command pose in the same direction.” Position repeatability is the only positioning performance indicator that industrial robot manufacturers specify in their brochures and varies between 0.010 mm and 0.100 mm. Methods for measuring repeatability were presented in ISO/TR 13309:1995. However, metrology has changed since then, so what are today’s methods for measuring position repeatability?
As I listened to a couple of presentations this week in Hong Kong about China’s massive efforts towards building robots locally, I couldn’t help but wonder how would the major industrial robot manufacturers react. Will ABB, FANUC, KUKA and Yaskawa eventually start lowering the prices of their robot arms? In 2013, one fourth of the nearly 37,000 industrial robots installed in China were made by local manufacturers according to the IFR, and this share will continue to increase. But the real threat that the leading robot manufacturers are facing does not necessarily come from Shenzhen, Shanghai or Guangzhou. It comes from small companies around the world.
There is no doubt that the robot arms of Universal Robots are by far the easiest industrial robots to use, as I already explained on this blog. The UR5 and UR10 are also robust, relatively light and affordable, and beautifully designed. But are they really safe to use without a fence?
In the user manual of UR5, Universal Robots warn to “not enter the safety range of the robot or touch the robot when the system is in operation.” Yet in their marketing material, they claim that their “robots can … operate without safety shielding for most applications and this is true for 80 per cent of current installations.” They specify that “this is because … in a collision, the robot delivers less force than the 150 Newton”. What is more, there are several videos where we see a UR5 bump into an operator, and the robot does seem harmless indeed. So is UR5 harmless or not?
There is hardly anyone in the industrial robot business who hasn’t heard about the revolutionary robot arms, UR5 and UR10, made by Danish manufacturer Universal Robots. The now hundred-employee privately-owned firm has sold more than 2,500 of their collaborative user-friendly robot arms. Our research lab has the UR5 robot arm as well as many other conventional industrial robots and even Rethink Robotics’ Baxter, but the UR5, with its stylish sleek design, is one of our favorite.
Vertically-articulated six-axis serial robots exhibit three types of singularities: wrist singularities, shoulder singularities, and elbow singularities. A wrist singularity occurs when axes 4 and 6 are coincident. A shoulder singularity occurs when the wrist center lies on a cylinder centered about axis 1 and with a radius equal to the distance between axes 1 and 4. Finally, an elbow singularity occurs when the wrist center lies in the same plane as axes 2 and 3.
When a robot is controlled in cartesian mode and passes near a singularity, the speed of some joints becomes suddenly very large and the cartesian velocity of the end-effector is significantly reduced. For this reason, trajectories that make the robot pass near singular configurations should be avoided.
The following video illulstrates the three types of singularities:
An excellent reference on this topic is the following scientific paper:
M.J.D. Hayes, M.L. Husty, P.J. Zsombor-Murray, 2002, “Singular Configurations of Wrist-Partitioned 6R Serial Robots: a Geometric Perspective for Users”, Transactions of the Canadian Society for Mechanical Engineering, Vol. 26, No. 1, pp. 41–55.
By 2014, China is expected to be the largest consumer of industrial robots, a striking development being driven by rising wages in that country. According to the International Federation of Robotics, 22,577 industrial robots were installed there in 2011, compared to only 14,978 in 2010 and 5,000 in 2009. Some of the world’s largest industrial robot manufacturers — FANUC, ABB, KUKA, and Yaskawa — have set up production units in China. ABB Robotics, for example, celebrated production of their first 100 robots at their plant in Shanghai in as early as 2005. In 2009, their Chinese R&D team even developed a brand new robot, the IRB 120, which I happily use in my undergraduate robotics course. KUKA alone, which enjoyed a 16% market share in China in 2011, claims to have sold more than 7,000 robots in that country. The Chinese have now established their own robot manufacturers. ESTUN Robotics, headed by a bright former fellow student of mine (Dr. Jiegao Wang), is one of these, as is GSK CNC Equipment. However, it wasn’t until July, 2011, that speculation began about the ways in which robots would replace workers in China. Continue reading “The truth about Foxconn’s Foxbot industrial robots” »