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Robotic Systems Control Laboratory (RSCLab) : Wearable robots that improve quality of people’s lives

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Contact Information

Country:
Republic of Korea

Year Submitted:
2017

University:
Sogang University

List of Team Members (with year of graduation):
Hanseung Woo, Hyunjin Choi, Byeonghun Na, Jungsu Choi, Pyeong-**bleep** Jung, Jangmok Lee, Cheolmin Kwon

Faculty Advisers:
Kyoungchul Kong

Main Contact Email Address:
hyunjin@sogang.ac.kr

Website:
http://robotics.sogang.ac.kr

 
Project Information

Title:

Robotic Systems Control Laboratory (RSCLab) : Wearable robots that improve quality of people’s lives

Description:  

The goal of our project is to develop wearable robot systems that help people walk. Walk-ON Suit is a wearable robot for people with complete paraplegia, and ANGELEGS is one for persons with partially impaired walking ability.

Products:       

NI myRIO-1900, NI sbRIO-9651 SOM, NI CompactRIO-9082, NI CompactRIO-9038, NI CompactRIO-9082, NI CompactRIO-9401, NI CompactRIO-9403, NI CompactRIO-9205

LabVIEW 2015, LabVIEW Real-Time Module, LabVIEW FPGA Module

The Challenge:

Developing wearable robots has many technical challenges. Fast encoder measurement acquisitions and real-time control are the essentials of assistive robot researches, because it should follows the human motion naturally and gives assistive torque when human needed. Our robots need to measure precise joint angles by diverse types of sensors and those have to be synchronized properly. NI devices such as myRIO, sbRIO, and CompactRIO and enabled us to apply many sensors and motor drivers with high compatibilities. The customable GUI of LabVIEW was helpful for us to design the UI of our robots. Many users who are not familiar with many numerical indicators can monitor the status of our robots by using the GUI.
As we developed robots for many years in RSCLab, we realized that the design of the wearable robots needs unique and special requirements. We initially approached to find one solution that could be applied to everyone, but by meeting patients with different diseases, we concluded that the assistive robot had two very different solutions. The requirements for complete paraplegia who do not have all the sensory and motor function of the lower limbs, and for those who need a little help to walk are very different. We had to distinguish those requirements and developed two different types of assistive robots.


The Solution:

I.    Wearable robots for people with impaired walking ability

 

Wearable Robot Project of RSCLab, Sogang University

 

Walk-ON Suit : A robot that release people from wheelchairs


Spinal Cord Injury (SCI) is caused by various accidents and diseases such as traffic accidents, fall-down injury, tumor, myelitis etc. Advances in the medical care of patients with SCI have significantly reduced the mortality rate and improved the life expectancy. Consequently, the demands of robots that can support the daily living of these patients are increasing steadily. Several wearable robots developed in recent years have proved that they are an effective device for the complete paraplegics in daily living.
The Walk-ON Suit is a wearable robot that generates lower extremity motions, particularly designed for persons with complete paraplegia. The overall system consists of a pair of robotic legs, a back-pack that includes a main control unit, circuits and batteries, a pair of crutches, user-interface display, safety gears, and rechargers. The robotic legs and a back-pack are firmly connected, and they are not disassembled except for maintenance purposes. The Walk-ON Suit has several unique features designed particularly for accomplish the missions of Cybathlon 2016, the Championship for Robot-Assisted athletes had held in Switzerland.
 

fig1_Development of WalkON Suit.png

Development of WalkON Suit

ANGELEGS : A wearable robot for assisting daily lives

ANGELEGS needs a totally different assistive strategy than Walk-ON Suit. Walk-ON Suit makes wearer’s lower limb to comply with the pre-determined motion that enables walking. Since, however, the wearer of the ANGELEGS is able to make a voluntary motion, the core technology is zero impedance actuation such that the robotic joint does not make resistive force for the wearer. The zero impedance actuation is realized by the series elastic actuation (SEA) mechanism and a control algorithm. As a result, the wearer does not feel uncomfortable with his/her movement. In addition to the zero impedance actuation, the ANGELEGS includes assist-as-needed (AAN) technology that generates assistive power only when needed. With the zero impedance actuation and the AAN technology, the wearer of the ANGELEGS is able to get motion assistance properly only when needed, without feeling uncomfortable with movement.
To realize the zero impedance actuation and AAN technology, eight encoders, seven IMUs, four foot pressure sensors, and four motors for hip and knee joint are installed on the ANGELEGS. The implementation of our core technologies are accomplished by signal acquisition and signal processing of many sensors, and the calculation of the control algorithm which requires a fast sample rate and high-level real time performance. NI’s devices and LabVIEW helped us implement the core technologies of the ANGELEGS quickly and efficiently.

 fig2_Development of ANGELEGS.pngDevelopment of ANGELEGS

 
II.    NI Devices in our projects

NI Devices in Our Projects

NI offers devices with a variety of performance. Among them, NI myRIO is the best device for the student projects. NI myRIO provides the enough number of FPGA gates, fast sample rate, and high-level real time performance. With NI myRIO and LabVIEW, students are able to easily implement signal acquisition, signal processing, serial communication, motor control, and so on.
EROWA is a wearable robot that introduced NI myRIO for the first time in our lab. The EROWA also includes the SEA mechanism like the ANGELEGS, but the main purpose of the EROWA was a research of the control algorithms rather than helping the patients. So the EROWA includes more encoders than ANGELEGS’s, and NI myRIO was able to provide just the number of DIOs required. As a result, all the user interfaces are eliminated, and the operation of the EROWA was controlled by the LabVIEW control panel through the wireless communication between the NI myRIO and the host PC. NI myRIO was the optimal environment for studying control algorithms, but lacked a DIO port to implement all practical aspects such as the user interface
To solve this problem, sbRIO-9651 (SOM) was used for the ANGELEGS. SOM does not provide an easy-to-use environment like NI myRIO . In order to use the SOM, the user has to design the carrier board. Nonetheless, the SOM provides an overwhelmingly lager DIO ports the NI myRIO , and the small size is well suited for mobile robot such as wearable robots. In addition, many FPGA gates of the SOM are sufficient to implement the large number of encoder counters and serial communications (e.g. SPI, I2C), and it fully meets the fast sample rate and real-time performance required to implement the core technologies of the ANGELEGS.

fig4_config_ANGELEGS_big.png
The NI CompactRIO(cRIO-9038) is an extremely powerful computing device that has 1.33 GHz dual-core Intel Atom processor, 8 GB nonvolatile storage, 2 GB DDR3 memory, Xilinx Kintex-7 160T FPGA. Since its operating system is NI Linux Real-Time, the real-time control of the robot is guaranteed. The large computation capability of the CompactRIO and the great performance of the FPGA system enable the accurate control of the motions of Walk-ON Suit and enhances the functionality of the robot.
The cRIO-9038 is able to accept two separated power inputs (i.e., primary and secondary power inputs). The primary power input is connected to a main battery for the CompactRIO, while the secondary power input is connected to a supplementary battery that is prepared for reacting to emergency situations related to the CompactRIO. By the use of two power sources, the risk of an accidental shutdown of the control unit due to a battery problem is significantly reduced.
The cRIO-9038 has eight module slots, and the Walk-ON Suit utilizes all the eight modules: six high speed DIO modules (NI-9401), one general DIO module (NI-9403), one analog input module (NI-9205). The high speed DIO module is used for receiving the incremental encoder signals and for receiving the sensor measurements through an SPI communication. The general DIO module is used for generating pulse-width-modulation (PWM) signals and for receiving the absolute encoder signals. Also, it is used for detecting the control signal by the switches and for indicating the robot status by the caution lamp. The analog input module used for sensing the current of motor drivers and for detecting the ground reaction force through FSR sensors.
In addition, the Mini DisplayPort of CompactRIO-9038 makes it possible to provide the human operator with a graphical user interface without any other peripheral; through a small monitor installed on a helmet, the human operator can monitor the control status of the robot.

fig5_config_WalkON_bi.png

 


III.    Intuitive algorithm design and implementation using LabVIEW

 



Control algorithm design and implementation for assistive robots

Since LabVIEW is a graphically programmable language, we were able to arrange and connect sequential algorithms intuitively. Various functions of LabVIEW enabled us to integrate all the algorithms without having to use other programs. In addition, we made subvis which were frequently used in control of assistive robots, and the build time was significantly reduced when we made multiple version of prototypes. Various debugging tools have also saved our time by quickly detecting and correcting errors.

FPGA Block Diagram.PNG


Monitoring system using network published shared variables

Mobility is one of the things we have considered the most because people have to move wearing our robots. Wearable robotic systems must be able to operate independently and status monitoring or UI should be able to be performed remotely. We use LabVIEW's network shared variables to configure the system to simultaneously monitor and transmit data across multiple targets. For example, ANGELEGS' measurement data is used by the robot's internal controller and is transmitted simultaneously to your mobile tablet PC and other remote tablet PCs.

 

fig6_GUI using LabVIEW.png

 

Real Time Block Diagram.PNG

 


Effective graphical user interface(GUI) configuration

The front panel of LabVIEW can contain diverse types of user interface. We made customized controls and indicators with different colors or background images. Instead of providing numerical data of joint angles of robots, we used 3D monitoring method for general users. In LabVIEW, we could easily import 3D model of stl format, and it enabled to build the 3D lower body monitoring system.

The pilot wearing the Walk-ON Suit is able to change a locomotion phase according to the environmental situation. The locomotion phase is divided into walking, standing up/sitting down, uphill/downhill, stones, tilted path, and upstairs/downstairs. The pilot controlled the Walk-ON Suit using switches on the crutches. And the pilot could monitor the control status of the Walk-ON Suit through a small monitor installed on stomach straps. The Mini DisplayPort of cRIO-9038 made it possible to provide the pilot with a graphical user interface without any other peripheral. We were able to reduce the development period from one month to two weeks.

 

fig7_WalkON Display.png

 


Recognition

[Oct 2016] Ranked 3 in Powered Exoskeleton Race of Cybathlon 2016, Swiss
    
[Dec 2016] An article in Enginnering.com
 
[Feb 2017] Finalist of the UAE AI & Robotics Award for Good, Dubai


   

 

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