Experimental characterization of the T-FLEX ankle exoskeleton for gait assistance

Biomechanical Effects of Adding an Ankle Soft Actuation in a Unilateral Exoskeleton

“…The T-FLEX robotic orthosis is added to the exoskeleton (see Figure 1 b), which has a flexible mechanism employing composite tendons that are coupled to the two servomotors of the device (Dynamixel MX106T, Robotis, CA 92630, USA). The tendons contain a rigid fishing rod material (eight filaments, Sufix 832, USA) and an elastic filament (Filaflex, 2.85 mm, Recreus, Spain) that produces the effect of variable stiffness to perform the dorsi-plantarflexion movement [ 28 ]. For more details concerning the structure of the devices please refer to [ 25 ] for the AGoRA Lower-limb Exoskeleton and to [ 28 ] for the orthosis T-FLEX.…”

“…The tendons contain a rigid fishing rod material (eight filaments, Sufix 832, USA) and an elastic filament (Filaflex, 2.85 mm, Recreus, Spain) that produces the effect of variable stiffness to perform the dorsi-plantarflexion movement [ 28 ]. For more details concerning the structure of the devices please refer to [ 25 ] for the AGoRA Lower-limb Exoskeleton and to [ 28 ] for the orthosis T-FLEX. The coupling of the two devices is shown in Figure 2 .…”

“…T-FLEX was developed with a different concept than the AGoRA unilateral lower-limb exoskeleton, in this case, T-FLEX, lacks a rigid structure [ 30 ]. Additionally, a series Elastic Actuator (SEA) generates the estimated torques during the gait cycle [ 28 ]. This control architecture was established as a multilevel structure, where a low-level controller comprises a PID controller.…”

“…The high-level controller is composed of a gait phase detection implemented by the AGoRA unilateral lower-limb exoskeleton in this high-level controller [ 24 ]. Moreover, T-FLEX implements a states selector based on a real-time gait phase detector [ 28 ] to assist the dorsi-plantarflexion during walking. The mechatronic integration of the two devices and the control variables can be found in [ 33 ].…”

“…Previously, the characterization of the T-FLEX tendons was performed to evaluate the configuration with the best performance. The results show that the tendons acting without the flexible filament have greater device performance [ 28 ]. T-FLEX has the potential to complement the AGoRA unilateral lower-limb exoskeleton according to its results in stationary therapy where a long-term study has found the recovery of motor control in a stroke patient [ 29 ].…”