A modular compliant actuator for emerging high performance and fall-resilient humanoids

Abstract

The application of humanoids in real world environments necessarily requires robots that can demonstrate physical resilience against strong physical interactions with the environment and impacts, that may occur during falling incidents, that are unavoidable. This paper introduces a modular high performance actuation unit designed to be robust against impacts and strong physical perturbations. The protection against impacts is achieved with the use of elastic transmission combined with soft cover elements on the link side. The paper introduce the details of the actuator design and implementation and discuss the effects of the soft cover and series elastic transmission on the reduction of the impact forces which reach the reduction drive of the actuator during impacts. The model of prototype joint, including the actuator unit, its elastic transmission and the driving link soft cover, is introduced and simulations were performed to study the effect of the elastic properties of the transmission and the soft cover on the reduction of the impact forces transmitted to the reduction drive. The results from the simulations are confirmed by experimental measurements on the real system under induced experimental impact trials, demonstrating the significant effect of the soft cover in the further reduction of impact forces. The performance of the proposed actuator unit in terms of physical robustness makes it ideal for the development of emerging humanoids robots that will be capable of surviving falls and recovers from them

TALOS: A new humanoid research platform targeted for industrial applications

“…For this reason three values are given for the maximum torques of Pyrène in Table IV, each considering different factors: max motor torque, max motor drive current, and max HD momentary peak torque. The third column gives numbers higher than WALK-MAN [2], but the first column is similar to the numbers given in [22] where the HD limitations are considered.…”

“…However, looking at [22], which gives a more thorough description of the actuator, one can remark that the numbers given in [2] do not consider the torque limits of the HD. For this reason three values are given for the maximum torques of Pyrène in Table IV, each considering different factors: max motor torque, max motor drive current, and max HD momentary peak torque.…”

“…In addition the peak motor and HD torques can be exceeded during a short time interval. For instance, the biggest HD available in WALKMAN is a CPL series, size 25, ratio 80 (according to [22]). According to the datasheet, the momentary peak torque is 255N m. This corresponds to the kind of peak torque we have experimented on HRP-2 for high-demanding motions during 10 ms, despite the lower limits of this robot 1 .…”

WALK-MAN humanoid lower body design optimization for enhanced physical performance

“…Furthermore the effects of impacts on the WALK-MAN joints are mitigated through the adoption of soft covers with a properly tuned stiffness. Benefits against impacts and stiffness selection of the soft covers are investigated with simulations and experiments in a related work [15]. Fig.…”

The Walk-Man Robot Software Architecture

“…The Walk-Man robot (see Figure 1) is a humanoid robot with 33 DoFs, each actuated by an electric series elastic actuator whose design is described in Negrello et al (2015). Each motor is controlled by its own electronic board at a frequency of 1 kHz.…”