Silke Pan wins silver in the Cybathlon with the TWIICE exoskeleton

Competing against athletes from five countries (United States, Russia, Korea, India and France) Swiss paraplegic athlete and handbike champion Silke Pan took part in the 2020 edition of Cybathlon, a cybernetic race organised by ETH Zürich. The former acrobat adorned the TWIICE exoskeleton especially designed for her by EPFL scientists. She raced through a 40 meter-long circuit that included seven types of obstacles like stairs, inclined slopes, rough terrain and a slalom around tables.

TWIICE is a lower limb exoskeleton developed by the EPFL research group REHAssist. It consists of actuated segments at the hip and knee joints that are rigidly interfaced with the thighs and the tibiae. A smart controller coordinates these segments to move according to desired gait trajectories that enable a person with spinal cord injury to walk.

Silke Pan took the silver medal in the finals on Saturday afternoon, just behind the Korean Byeong-Uk and his team Angel Robotic 1. "A second place is just wonderful!" she reacted after the results were announced. "I was responsible for bringing to success all the work that had been done before by the TWIICE team. We worked together to perfect every aspect of the race. On D-Day we all gave our best, and we have nothing to regret. We can be proud of what we have achieved, of all the improvements we have made to the exoskeleton since 2016. The Cybathlon is a motivation to go even further and in that sense it has allowed us to progress."

Mohamed Bouri, head of the REHAssist group, was not hiding his satisfaction: "The team has invested itself fully and this result is well deserved. We are particularly happy for Silke, who wanted a victory so badly and was afraid of disappointing us. It couldn't be the case, because it was a team effort. There are no winners or losers, only hope, because the Cybathlon pushes us to make assistive devices more accessible for people with disabilities. Looking ahead, I would be happy to see this development result in a product marketed by a future startup that would have every chance of becoming a technological flagship in the Lake Geneva region. The Cybathlon has allowed us to explore several control strategies and efficient trajectories. To do even better, we need to push back the limits of our knowledge even further, and that is the beauty of science". Mohamed Bouri also thanked the people in the TWIICE team: Tristan Vouga, Romain Baud, Jemina Fasola, Alireza Manzoori and Julien Pache.

Tristan Vouga, EPFL Cybathlon team leader and co-designer of the TWIICE exoskeleton, believes that "the Cybathlon has achieved its goal, because all the teams have made great strides in their technological developments since 2016. Today there are no losers, we are all victorious while facing the limits that a disability can represent. I am very proud to be part of such a close-knit and dynamic team. I would like to thank Silke for this magnificent feat, she has inspired us throughout this great adventure with unfailing determination!"

The result of extensive training
A professional athlete, Silke Pan is more than acquainted with intense competition. Throughout the year, she trains daily on the handbike and in hand balancing, 3 to 5 hours per day during the height of the training season. Every day, she goes outside with her handbike and does endurance, interval and power training in preparation for various hand-bike regional and international competitions, like Europe's Cup, the World Cup, the World Championships and the Paralympics, that are planned to resume in 2021.

For the past month and a half, Silke Pan and the EPFL TWIICE team have been training one afternoon per week at EPFL's Lausanne campus in preparation for the race. Wearing TWIICE, Pan started by learning all the gestures of the circuit with slow and deliberate movements. As the training sessions continued, Pan progressively stepped up the intensity and tempo of her movements to increase her speed. During the race, she was followed by two scientists to ensure her safety.

Improvement of the exoskeleton
“Since the beginning of the training sessions, the exoskeleton has been in constant improvement thanks to Silke's input and her drive to win,” explains Tristan Vouga. “We gained 4 minutes in the last month and 45 seconds during the last training session alone. Our latest upgrade consists of a more flexible foot that can conform to the terrain. More generally, the latest version of the exoskeleton is much more ergonomic and provides more autonomy for its pilot, so Silke for instance can now go directly from her wheelchair into the exoskeleton by herself."

The current version of the exoskeleton, called TWIICE One, is more compact due to improved design of the motors, thanks to a collaboration with Swiss industry partner Sonceboz SA, specialized in electrical motor manufacturing. According to Vouga, TWIICE One is therefore easier to use than the 2016 model: it is closer to the body because the motors are two times more compact and two times stronger. Other strategic partnerships include a collaboration with the local company Fischer Connectors for improving the ergonomics and usability of cables.

Online race
The latest coronavirus sanitary measures prevented the Cybathlon from happening live in Zürich. Silke Pan's participation in the exoskeleton race was therefore organized and pre-recorded at EPFL. The winner was determined based on three rounds of the race. The performances of each athlete was recorded in the presence of a referee from the Cybathlon committee, in their country of residence.

A fundamental right to mobility
“An exoskeleton to assist a person affected by paraplegia does not only concern mobility. It also concerns basic human rights, the right to live as others, the right to share social spaces, the right to walk and to own vertical space,” says Bouri. “Alongside our colleagues in Zürich, our participation via EPFL at the Cybathlon promotes an attitude in favor of increasing access to exoskeleton technology for providing daily assistance to a wider audience.”

The development of TWIICE first began in 2015. The exoskeleton team has won 3 years in a row the "Cybathlon experience", a European exoskeleton competition also organized by the Cybathlon committee. The Cybathlon is a Swiss-organized competition that happens every 4 years to promote
technologies that assist people with impairments in their daily activities.

EPFL’s participation at the Cybathlon is possible thanks to the generous support from EPFL's Vice Presidency for Innovation and its initiative Smart Move, the Fondation Avenir Plus, the Bâloise Group, Fischer Connectors SA, Sonceboz SA, NCCR Robotics and EPFL’s Center for Intelligent Systems.

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