By Dave Wilson, Academic Marketing Director, National Instruments
Look no further than the Fukushima nuclear plant disaster of 2011 to see the importance of developing equipment to help with the decommissioning of nuclear facilities and the decontamination of waste. Such equipment must operate in the presence of high radiation, heat, humiditiy, caustic or acidic fumes, and limited visibility. Currently available robotic manipulators are inadequate due to limitations in radiation tolerance, dexterity, working range and payload. Enter the ModuMan 100 remote manipulator from James Fisher Nuclear, a robotic arm with six degrees of freedom, a 2.3m reach with 5mm accuracy, and a payload capacity of 100kg (220 lbs) at full stretch. The ModuMan 100 employs hydraulic actuators for the power joints and can be deployed through a standard nuclear industry 300mm penetration port or on a carrier system.
Here is a video of the manipulator in action:
Design goals for the ModuMan 100 manipulator included making the manipulator modular, cost-effective, and maintainable, while making best use of off-the-shelf solutions. The multi-mode HMI (human-machine interface) and control system for the manipulator are based on a National Instruments (NI) CompactRIO Rugged and Reconfigurable Control and Monitoring System programmed with NI’s LabVIEW Graphical Programming Environment and LabVIEW FPGA.
According to James Fisher Nuclear, CompactRIO was ideal for modular testing and prototyping. When hardware wasn’t available, the company’s development engineers could simulate inputs, which ensured the software was functionally correct before incorporating it into hardware. When individual hardware components became available during the manufacturing process, engineers could carry out loaded and unloaded single-joint testing using the CompactRIO. Engineers also discovered that the NI Compact RIO controller was rugged, reliable, easy to maintain, and scalable—which permits easy future modifications to the system.
NI’s CompactRIO controllers incorporate real-time microprocessors and Xilinx FPGAs. Engineers at James Fisher Nuclear reserve the FPGA for all of the ModuMan 100’s safety-critical processing functions while a comprehensive fault analysis system runs on the real-time processor. Safety-critical faults immediately trigger the FPGA to put the arm into a safe state and inform the user on the HMI. Noncritical faults are logged to the internal nonvolatile memory of the CompactRIO system as well as the HMI’s hard drive. The thoroughness of the fault analysis system eases post-failure investigation.
The ModuMan 100 has undergone in-house and off-site testing and is currently undergoing longevity trials.
Note: Dr. Carwin Jones of James Fisher Nuclear Ltd and Justin Gallagher and Dr. David Keeling of Key Engineering Solutions in the UK submitted this project to the NI Engineering Impact Awards 2014 competition. It was a finalist in the Machine Control category.