Exoskeleton for Improving Mobility

Exoskeletons have the potential to improve the mobility of individuals who suffer from a variety of gait pathologies, such as stroke victims or those with lower-body paralysis. We have been researching using these powered exoskeletons to improve mobility for several years, and are continuing to do so with our latest exoskeleton, Quix.

IHMC will use Quix to compete at the 2020 Cybathlon Powered Exoskeleton Race in Zurich, Switzerland. Quix is also the device that helped IHMC become one of the finalists in the Mobility Unlimited Challenge, a competition organized by the Toyota Mobility Foundation that attracted 80 entries from 28 countries. Over the summer of 2020, we also will be demonstrating Quix in Tokyo as part of the judging for the Challenge.

Quix Device

Quix is a powered exoskeleton that IHMC is developing to provide increased mobility and independence to people with paralysis. The device will allow users to stand up and walk through a variety of environments, including up and down stairs and ramps, and across both flat and bumpy terrain.

Powered actuation at the hip (both flexion/extension and adduction/abduction), knee (flexion/extension), and ankle (plantarflexion/dorsiflexion) provide smooth and natural walking motions. These eight actuators enable the device to exhibit a wide variety of movements, utilizing a combination of actuation in both the sagittal and frontal planes. Each actuator weighs about 2.5 kg and can achieve a peak torque of 200 Nm and peak speed of 7 rad/s. The exoskeleton is powered by two 6S lithium polymer batteries that supply a maximum operating time of approximately 1 hour of heavy usage. These batteries are housed in the backpack and can be hot-swapped to allow for extended run times.

Each actuator houses its own required electronics, including a motor driver and logic board. The actuators in each leg are daisy-chained to each other by the power and data lines that originate in the backpack. The software control algorithms are dependent on commands from the pilot and feedback from the exoskeleton's sensor suite. An inertial measurement unit (IMU) provides orientation of the exoskeleton, which can be used to help balance the device. Pressure-sensing footpads provide center-of-pressure feedback which is a key parameter for various walking controllers. A set of push buttons and LCD screen on the crutch wirelessly transmit commands, allowing the user to select among different behaviors such as sit, stand, and different walking speeds.

Previous Exoskeleton Iterations

Mina v2 Hardware

Mina v2 was developed for Cybathlon 2016, which featured a new actuator design initially developed for the Grasshopper exercise device. This exoskeleton featured powered ankles, the use of which we are exploring to develop faster and more stable walking than previous versions.

NASA-IHMC X1 Mina Exoskeleton

The X1 and Mina v1 powered lower extremity exoskeletons were jointly developed by NASA Johnson Space Center and IHMC. The focus of this collaboration was to develop a robotic device for a range of applications, including mobility assistance for abled and disabled users, rehabilitation, and exercise. The robot features torque controllable actuators at the hip flexion/extension and knee flexion/extension and passive joints to allow for hip ab/adduction and hip internal/external rotation. The powered joints are capable of variable impedance, ranging from zero impedance for transparent mode to high impedance for stiff position control. The links of the exoskeleton can be adjusted to the user’s body size such that the powered joints are co-located with the user’s joint, creating an anthropomorphic structure.