Developing Interplanetary Robotics with NI Technology

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"Because NI software and hardware are highly integrated and capable of handling some of our toughest challenges with easy-to-use functionality, we have realized many time- and cost-saving benefits."

- Sean Dougherty, MDA-US, formerly Alliance Spacesystems LLC

The Challenge:
Creating robotic systems rapidly and cost-effectively for prototyping and demonstrating space exploration applications.

The Solution:
Combining NI LabVIEW software and modular hardware to create multiple robotic systems, including a ground-based demonstrator arm for the Mars rovers, Spirit and Opportunity, within short design-to-deployment time frames.

Author(s):
Sean Dougherty - MDA-US, formerly Alliance Spacesystems LLC
Thomas Debus - MDA-US, formerly Alliance Spacesystems LLC

 

MDA-US, formerly Alliance Spacesystems LLC delivers space robotics, mechatronics, structures, and embedded systems engineering for systems operating in extreme environments on Earth, in outer space, and on Mars. Our products are used on interplanetary spacecraft, telecommunications and scientific satellites, and in many challenging terrestrial applications. We developed the robotic arms for various NASA missions to Mars, including the Phoenix Lander and Mars exploration rovers, Spirit and Opportunity. We also created a robotic solution for a proposed Hubble Space Telescope repair mission. Because of the unique nature of many of our projects, we design, fabricate, assemble, and test these robotic systems in-house within tight timelines and budget constraints and according to the very strict processes required for operating in such extreme conditions.

Challenges of Embedded Design and Robotics

Almost everything we do has never been done before. Because of the pioneering nature of our work, our primary challenge is to design and develop completely unique systems in a timely manner and within limited budgets. We have to fully use our prior experience, and we often integrate existing technologies into a new system. However, with short deadlines we have to quickly adapt and iterate on a design that may involve many different disciplines. Consequently, we continue to explore new ways to efficiently integrate complex mechanical systems with software and advanced control systems.

Robotics development requires engineers with expertise in many different engineering disciplines. They must understand how a mechanical system will affect the design of the control system. Also, they have to understand the software and realities of working with electronics and measurements that are noisy or imperfect. Digital control, control loop rates, and determinism all become important factors when designing robotics systems. Therefore, successful robotics design requires understanding and integration of all these interdependencies and then implementation of our systems engineering processes to deliver the most effective product for our customers.

Widely Implementing NI Tools

To maintain an efficient and dependable design, prototyping, and deployment process, the MDA-US, formerly Alliance Spacesystems, robotics design lab uses NI software and software-defined modular hardware. For aerospace applications, NI technology helps us rapidly develop, demonstrate, and test a concept prior to implementation on flight hardware. NI tools were especially useful during concept demonstrations and the prototyping phase of our in-space robotic arms.

In addition, our use of NI products has closely followed NI platform development. We began by standardizing our test and validation processes on NI test and data acquisition technology and recently expanded our implementation of NI tools to our prototyping and design phases. With the continually growing selection of flexible products from NI, now we can use an array of NI tools for embedded systems that previously required a mixture of various hardware systems.

We use the LabVIEW Real-Time and LabVIEW FPGA modules for software development, and also make extensive use of the NI motion, control, and controller area network (CAN) libraries. The NI Real-Time Execution Trace Toolkit also serves as a very useful tool for optimizing performance in future developments. We standardized much of our hardware on the NI CompactRIO platform, PXI embedded controllers, and NI Single-Board RIO. These tools have provided the flexibility we need, particularly for motion control, an area in which many of our designs have a wide range of requirements such as the need for large quantities of distributed actuators and the ability to implement our custom control algorithms when an application necessitates higher performance than what traditional proportional integral derivative (PID) controllers can support. The integrated software and hardware from NI has helped us efficiently meet these types of challenges.

Technical and Business Benefits of NI Software-Defined Technology

NI technology provides three primary advantages – seamless software-hardware integration, flexible-yet-powerful performance, and intuitive ease of use. These benefits help us meet our technical development and our bottom-line requirements.

The selection of NI software-defined products provides all the tools we need in one fully integrated platform. The software, hardware, and drivers integrate smoothly, which helps us incorporate them into a reliable, real-time platform. This integration makes our processes efficient, and the intuitive, easy-to-use nature of NI software-defined technology further enhances our efficiency. For example, the graphical programming of all LabVIEW tools greatly simplifies complex tasks, such as advanced control algorithm development and hardware-in-the-loop (HIL) test configurations. This ease of use complements, rather than sacrifices, the advanced, high-performance functionality of NI tools so we can integrate all of our tools from the design and analysis to the actual control of the real hardware.

Because NI technology is easy to customize, operate, maintain, and integrate, we have successfully used it in even our most sophisticated applications. We have also used it to focus on the engineering problems and the “big picture” rather than wasting effort trying to get hardware to work or communicate at the lowest levels. NI has done much of the integration groundwork so that engineers do not have to. Therefore, we can also use NI technology throughout our entire process with the development and testing of a controller in LabVIEW at our desk on a Windows OS machine, for instance, and implementing the system on an NI real-time, embedded system with a real robot. Then we implement LabVIEW as the user interface and the data acquisition system that helps us test, tune, iterate, and improve the system.

In addition, because the same vendor delivers the software and hardware, we have confidence that the interfaces have been thoroughly tested and we will have dependable, long-term support. This helps maintain rapid development times and reduced costs. The ability to develop systems very rapidly for our customers translates into impressive bottom-line business benefits. For example, in approximately three months we designed and built a robotics demonstration for making repairs to the Hubble Space Telescope for NASA. This included a custom X-Y-Z robotics platform with tool drive, tool change-out capability, and a vision system. With traditional solutions, this complex assignment could have taken at least one year to complete. However, with LabVIEW, CompactRIO, and other NI tools, we delivered a prototype in approximately 90 days. We would not have successfully completed this assignment without the integrated NI products.

For many of our other projects, we would not have been able to meet our schedules without the capabilities offered by NI. Because we are focused on one-of-a-kind solutions rather than mass production, nonrecurring engineering makes up a major part of our cost, and time certainly equals money on our projects. Using NI products easily saves us weeks or months on many of our projects, which typically last from six to 18 months in duration, and the time savings we have realized by using NI technology represent significant cost savings.

Complex Problems Solved with LabVIEW, CompactRIO, NI Single-Board RIO, and NI C Series Modules

Space robotics is a demanding application that requires flexibility and customization because all of our use cases are different. Robotics also requires tools that are easy to use so that the engineer can focus on the system and the interactions between the various subsystems. LabVIEW, CompactRIO, and other NI tools are unique in their ability to provide power and flexibility while being extremely easy to implement in the real world. They also offer the necessary reliability and power we need in terms of the hardware, software, and real-time OS.

We used NI Single-Board RIO to assist in the creation of an automated “Mosquito” soil-hardness tester tool. This system had to be a compact, field-operable system that was very rugged and reliable, which required rapid prototyping of a system with numerous custom interfaces. Because it was a customized system, we initially had several processors and various boards to accomplish each task. This was a systems-engineering issue that became problematic because our configuration was inefficient in trying to support all of the different interfaces and features. By incorporating NI Single-Board RIO, we captured all of the required functionality and flexibility on a single embedded device. We combined NI Single-Board RIO with several C Series modules, including a CAN card to interface to the tester’s intelligent motor controller, an RS232 interface, and an SD memory module for storing data.

Using NI hardware and software, we solved a different challenge for our Aerospace Robotics Testbed (ART). This application demanded a real-time OS and the utmost in reliability in stability and control. We needed to develop a system that performed several tasks – analyze the robotic arm, including the hardware and controller; visualize the arm motion in its workspace; compute the inverse kinematics and dynamics; and, at the same time, provide an intuitive user interface and deal with a large amount of telemetry from the arm. For this arm, we used CompactRIO with low-level control algorithms residing on the field-programmable gate array (FPGA) and higher-level algorithms, such as the inverse kinematics residing on the embedded, real-time processor. To create something that can accomplish all of these tasks for a flight system could take years when using traditional hardware and software systems, but the seamless integration between NI hardware and software helped implement initial, up-front development faster.

NI Technology Provides a Strategic Advantage

The technical and bottom-line benefits we have gained by implementing NI tools have created multiple efficiencies throughout our design, prototyping, and demonstration processes. The high level of complexity and novelty involved in all of our projects, as well as the short time frames in which we work, demand powerful and flexible design and prototyping solutions. Because NI software and hardware are highly integrated and capable of handling some of our toughest challenges with easy-to-use functionality, we have realized many time- and cost-saving benefits. Considering such significant efficiencies, using NI technology to prototype and demonstrate many of our robotics projects is a major strategic advantage.

Author Information:
Sean Dougherty
MDA-US, formerly Alliance Spacesystems LLC

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