This paper aims to present the integrated design, development, and testing procedures for a state-of-the-art torsion-based series elastic actuator that could be reliably employed for long-term use in force-controlled robot applications. The main objective in designing the actuator was to meet weight and dimensional requirements whilst improving the long-term durability, ensuring high torque output, and containing its total weight. A four-fold design approach was implemented: (i) following recursive design-and-test procedures, an optimal torsional spring topology was unveiled with the help of SIMP (Solid Isotropic Material with Penalization) topology optimization method, (ii) the proposed spring was manufactured and multiple specimens were experimentally tested via a torsional test machine to validate linearity, loading rate response, and mechanical limits, (iii) the actuator’s thermal response was experimentally scrutinized to ensure that the generated heat was dissipated for long-term use, and (iv) the fatigue life of the spring was computed with the help of real-life experiment data. Having concluded the development and verification procedures, two different versions of the actuator were built, and preliminary torque control experiments were conducted. In conclusion, favorable torque tracking with a bandwidth of 19 Hz was achieved while peak-to-peak torque input was 20 Nm.

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In this paper, we present our research study concerning the design and development of an exoskeleton that aims to provide 3D walking support with minimum number of actuators. Following a prior simulation study, the joint configuration was primarily determined. In order for the exoskeleton to possess advanced characteristics, the following design criteria were investigated: i) all the actuators (hip/knee/ankle) were deployed around the waist area to decrease leg weight and improve wearability, ii) custom-built series elastic actuators were used to power system for high fidelity torque-controllability, iii) 3D walking support is potentially enabled with reduced power requirements. As a result, we built the first actual prototype to experimentally verify the aforementioned design specifications. Furthermore, the preliminary torque control experiments indicated the viability of torque control.

This study presents the hardware development and low level controller structure of an upper-body exoskeleton that is equipped with high torque-to-weight ratio actuators. It is intended to be used in industrial applications. The exoskeleton can be adjusted for various arm sizes and can ideally be used by an operator that has a height within the range of 160 cm and 200 cm. The robot structure was comprised of 4 degrees of freedom, 3 of which are powered via custom-built series elastic actuators with high power-to-weight ratio and real-time torque control capability. The 4 th joint, a prismatic joint, was added to accommodate for glenohumeral head elevation, enabling the system to attain a workspace that is suitable for industrial tasks. The exoskeleton is equipped with a two-piece end effector (E1 and E2) to enable the power augmentation tasks. In order to check torque controllability, initial experiments of the system were conducted on a joint level. As a result, 20 Hz of control bandwidth was achieved when the peak-to-peak torque inputs were 20 Nm.