Amazing Mechatronic Exoskeletons Making Headway Towards FDA Approval

Andrew Wheeler | Comments | February 23, 2018

Throughout history, engineers have made phenomenal contributions toward improving the standard of living for the masses by creatively applying the known laws of science to inventions that sometimes completely alter everyday reality, but usually improve it in increments.

Faith healers have long sought to convince the faithful that they can perform miracles, like restoring vision to the blind, curing terminal illnesses and healing broken bones through various powers of divination and theurgy.

If a loved one is seriously injured or falls ill, you might be thankful that you are living in 2018, where the chances of recovering from treatments based on scientific empiricism developed in Western medicine are higher than they’ve ever been in our brief history as a sentient species.

Of course, there are many maladies that remain permanent, such as severe spinal injuries like paraplegia that leave the afflicted unable to walk.

With new advances in customizable robotics though, some intrepid inventors are attempting to give paraplegics the ability to walk again.

At SOLIDWORKS World 2018, this mechatronic exoskeleton was presented by an employee of a company called SG Robotics. Inventions like these are sparking new hope for paraplegics and partially mobile patients. (Image courtesy of Michael Alba.)

The WalkON Suit and ANGELEGS Devices from SG Robotics

Starting in 2014, Sogang University Professor of Mechanical Engineering Kyoungchul Kong was inspired to begin research on wearable robot exoskeletons after observing a fellow lab partner who was paralyzed from the waist down. Using SOLIDWORKS Research Edition as his primary development software, Kong set out to create a wearable device that would help his friend and other paraplegics regain mobility.

Pictured here is Kong’s first invention for paraplegics, the WalkON Suit, which was inspired by a desire to help his lab partner afflicted with paraplegia. (Image courtesy of SG Robotics.)

After founding a company called SG Mechatronics (which was changed in 2017 to SG Robotics), Kong spent a few years designing and creating a mechatronic exoskeleton, which he ended up calling the WalkON Suit. Designed to give paraplegics the ability to walk with complete autonomy and freedom from traditional human assistance, digital prototypes of the WalkON Suit were tested using powerful simulation software. Kong began to develop physical prototypes and eventually had a real version of the WalkON Suit.

In 2016, Kong appeared onstage at Cybathlon, a world championship for disabled athletes competing against each other with the aid of robotic augmentation.

In his WalkON device,Cybathlon athlete Byeongwook Kim completed six stages within the time limit to take home a bronze medal at the 2016 games, which were held in Switzerland. (Video courtesy of SG Robotics.)

Several iterations of the original WalkON Suit included the addition of automatic movement features and a sensor-laden motion detection system, which worked well in theory but were not actually favored by paraplegic patients who tested it. The patients ended up preferring manual controls to work the robotic exoskeleton.

The brushless EC 22 from Maxon Motors with Hall sensors powers the leg assemblies of the WalkON Suit. It has a maximum speed of 45 revolutions per minute and a driving force of 250 Newton meters. Four redundant motors allow for the WalkON Suit’s legs to be constantly in motion. (Image courtesy of Maxon Motor USA.)

With customized knee, ankle and foot orthotics for a paraplegic patient, the WalkON Suit stays stable but not rigid in a standing position—thanks to a pneumatic actuator in the exoskeleton that provides resistance to keep the user upright and buoyed. It is not connected to any powered pneumatic pump, nor does it provide resistance when the user is in motion climbing stairs or walking.

Kong didn’t want his WalkON Suit to ignore tricky issues that prevent paraplegic patients from successfully using robotic exoskeletons, including involuntary oscillatory muscular contractions and joint contracture. Another thorny issue is that 80 percent of complete paraplegics suffer from osteoporosis, so inhabiting an exoskeleton can be very risky if something goes slightly awry or isn’t designed with total harmonic precision.

From WalkON Suit to ANGELEGS

To properly address patients who still had partial mobility, Kong moved SG Robotics in a slightly new direction, creating a lightweight robotic wearable called ANGELEGS.

ANGELEGS, from SG Robotics, utilizes a zero-impedance actuator that allows users to move normally without disrupting their natural motion. Weighing only 12kg (26.46lbs), its battery lasts for 3 hours. It uses intention detection to streamline motion, and mechanical sensors in the shoe attachment monitor the user’s gait in realtime while also measuring exercise information. (Image courtesy of SG Robotics.)

At SOLIDWORKS World 2018, Kong described his inspiration for the ANGELEGS device, saying, “I met another person in the laboratory. He was an elderly person, but he was not a complete paraplegic. So I had to develop something new that just lightly assists human motion.”

Kong then laid out an overview of the process of designing and manufacturing ANGELEGS: He and his team 3D scanned the person’s legs, imported the file, designed the mechanical frames and electric circuits, performed a safety check through simulations, performed a design check, manufactured the parts by a combination of 3D printing and CNC machining, built the assembly, implemented the controller and performed a usability check.

The ANGELEGS is capable of intention estimation, which predicts human motion based on body kinetics and gravity compensation (reducing body weight), as well as hemiplegia assistance for post-stroke patients.

SG Robotics became the first member to be accepted to the Dassault Systèmes Entrepreneurship Program, and ANGELEGS may soon become an FDA medical-approved device in the United States and may be approved for use in South Korea as well.SG Robotics is currently researching and collecting clinical data at five hospitals in South Korea to make more improvements and iterations on the ANGELEGS device.

In the future, the ANGELEGS device will offer Internet of Things connectivity for functions such as health monitoring, gravity compensation for heavy manual labor and hemiplegia assistance for post-stroke patients.

About the Author


Andrew Wheeler is an optimistic skeptic whose lifelong passion for computer hardware has led him to 3D printing and his latest technological passion, Reality Computing.

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