With a focus on autonomy, flexibility and safety, Boston Dynamics applies its robotics expertise to a commercial robot solution with automation and integrated safety technologies from Beckhoff
As the intralogistics industry speeds ahead, mobile robotics will become even more critical. Many solutions move cartons and totes from point A to point B. Limitations arise when they lift cartons from conveyors or out of semi-trailers and shipping containers for palletizing and depalletizing. To better meet warehouse and distribution center requirements, Boston Dynamics developed an innovative robotic solution called Stretch™. The autonomous mobile case-handling solution for unloading applications combines the robotics leader’s three decades of R&D with automation and integrated safety technologies from Beckhoff.
Designed from the ground up to meet the needs of this industry, Stretch features a compact, highly maneuverable base that safely moves in any direction and navigates ramps or other obstacles. A perception mast uses advanced computer vision for fast and precise case detection. What sets Stretch apart is its purpose-built robotic arm with seven degrees of freedom and adaptive vacuum gripper, which works with the perception system to manipulate the broadest possible set of cartons. A high-capacity battery option can power Stretch through two full shifts to support continuous, flexible unloading.
Like Boston Dynamics’ other robot designs, Stretch helps people manage dull, dirty and dangerous applications in manufacturing and warehousing, explains Matthew Meduna, Technical Director of Hardware Engineering, Stretch: “Spot® users find great value in having a robot that effectively automates tasks like industrial equipment inspection, hazardous gas detection or investigation of suspicious packages to keep humans out of harm’s way. Similarly for Stretch, there is incredible value in automating tasks that are difficult to consistently staff in warehouses and 3PL facilities, such as trailer unloading.”
Stretch development team puts human safety first
Boston Dynamics had several goals for Stretch. The robot needed to offer the autonomy to intelligently react to changes in its environment and handling requirements, which is another key differentiator in the market. It needed to extend the world-class manipulation capabilities of Boston Dynamics’ other platforms to provide significant customer value in intralogistics. And it needed to provide the mobility to bring the autonomy and manipulation capabilities from job to job throughout the day. But to achieve these capabilities with high system availability, the Stretch solution needed to provide robust safety capabilities to prevent injuries or damage.
“We had to find a solution that supported all the different types of sensors and safety features required for the robot and offer reliable support for black-channel safety communication protocols over Ethernet,” Meduna says. “Beckhoff provided the perfect fit with TwinSAFE integrated functional safety and machine control technologies.”
The Boston Dynamics engineering team began working with local Beckhoff experts, including Regional Sales Engineer Brian Buck, during the early stage of the Stretch design in 2019. “The flexibility and wide range of options Beckhoff offers were decisive factors in Boston Dynamics choosing to use our technologies both in the robot and off the robot as part of the total solution for control and safety,” Buck adds.
TwinSAFE leverages the trusted Fail Safe over EtherCAT (FSoE) standard, which is TÜV-certified, even enabling the passing of safety states over Wi-Fi in a hierarchical safety architecture. FSoE communicates safety data over the standard EtherCAT industrial Ethernet system using a black-channel approach. The advantages of EtherCAT ¾ real-time communication, free selection of topology, up to 65,535 nodes on one network, extensive diagnostics and more ¾ are available to the safety system. The TwinSAFE solution reduces cabling, hardwiring of safety switches and management of different software packages, which helped simplify safety system implementation.
Stretch also gains an advantage through use of TwinSAFE SC (single channel) from Beckhoff. This enables the addition of standard analog signals for safe position and safe velocity of the mobile robot. TwinSAFE SC supports standard signals for both control and safety tasks, helping machinery achieve a safety level up to category 3, performance level d. Furthermore, specialized safety encoders are not required. Instead, standard encoders can be utilized with a full offering of TwinSAFE SC encoder input signal types including SSI interface, Sin/Cos, EnDat 2.2, incremental encoder RS422 and incremental encoder 24V HTL.
Standardized, streamlined and above all, safe
Each Stretch robot features a CX5130 embedded controller inside, which monitors the system and communicates with a separate PC for fleet management. “The CX5130 determines if the robot is in a sufficiently safe environment to allow motion, and it engages the power distribution zones and releases the brakes when requested by the controls software,” Meduna says. Along with several EtherCAT Terminals, TwinSAFE and TwinSAFE SC Terminals, including the EL1918, EL2912 and EL2904, handle safety functionality. These are critical for monitoring joints of the robot arm and the speed and angles of the wheels. Two single-channel encoder interfaces validate the accuracy of positioning data: EL5001-0090 for SSI and EL5101-0090 for incremental encoders with differential signals (RS422) or TTL single-ended signals.
A remote fleet management panel ensures safety of the overall work zone using a CX8190 embedded controller with a similar lineup of EtherCAT and TwinSAFE modules. These read inputs from E-stops, safety I/Os, cart or conveyor detection, and dock or shore cable detection. “This control setup handles any safety communication in the cell surrounding where Stretch is working,” Buck explains. “In addition to stack-light control, these technologies enable the fleet manager to control the safety state of the Stretch robot wirelessly over a local Wi-Fi network. For example, if an E-stop is pressed or a person enters the work zone, Stretch will go into a safe mode.”
TwinCAT 3 automation software from Beckhoff delivered an end-to-end engineering environment and runtime for the safety application. The Boston Dynamics team relied on TwinCAT for programming PLC and safety logic and used the real-time Ethernet communication to talk UDP to other computers in the solution. With TwinCAT, engineers can program in the languages that they are most familiar with or that best fit the project, including the available IEC 61131-3 languages and their object-oriented extensions, function blocks and computer science standards in Microsoft Visual Studio™. “The support for these standards allows us to consider a large ecosystem of automation components,” Meduna says. “This is extremely important as we continue to develop integrated solutions.”
Mobile robot delivers ROI by the truckload
The commercial launch of Stretch occurred in early 2022 with clear differentiators from other mobile robots on the market. Stretch can autonomously unload trucks and shipping containers and remains incredibly flexible. With a powerful vacuum gripper and advanced vision system, the robot handles a variety of package types up to 50 pounds with no requirement for SKU number pre-programming or box size information. It can even autonomously recover any packages that shift or fall during the unloading process.
Beckhoff’s robust portfolio and reliable support from sales and applications engineers helped ensure the successful launch. The large variety of devices and options from Beckhoff allowed Boston Dynamics to rapidly enhance the functional safety coverage of the Stretch robot in a very short timeframe. “This has allowed us to be nimble with new design changes and supported many different off-the-shelf sensors and components,” Meduna says.
Going forward, Boston Dynamics plans to use wide-ranging Beckhoff technologies to best support unique customer applications, ensuring the utmost safety and reliability as robotics technologies evolve. “We are always developing and releasing new software, hardware and systems improvements to increase our robots’ ability to help people in real-world applications,” he adds. “Innovation is the lifeblood of our company. Boston Dynamics was built on nearly 30 years of research-and-development into advanced mobile robots, and those efforts are coming to fruition with commercially available products like Stretch.”