Multistable series elastic actuators: Design and control

Abstract

In this paper we propose a novel actuation concept, consisting of a conventional DC motor in series with a compliant element having multiple configurations of equilibrium. The proposed device works similarly to a traditional series elastic actuator, where the elasticity increases safety and force control accuracy, but presents the possibility of achieving higher efficiency and releasing energy at a higher bandwidth. An introduction on the mechanical properties of the multistable element explains its working principle and provides simple model-based guidelines to its design. We characterize the actuator and propose a robust algorithm to control both storage and rate of release of its elastic energy. Using only an incremental encoder on the motor's axis, we show that we can reliably control the position of the actuator and its convergence towards a state of stable equilibrium. The proposed robust control architecture sensibly improves the tracking accuracy with respect to conventional PID controllers. Once reconfigured, no additional energy from the motor is required to hold the position, making the actuator appealing for energy-efficient systems. We conclude with a discussion on the limitations and advantages of such technology, suggesting avenues for its application in the field of assistive robotics.

Solving the inverse kinematics problem of discretely actuated hyper-redundant manipulators using the multi-module searching method

“…Today researchers use discrete actuators in a variety of fields and devices such as grippers [3][4][5][6][7][8][9], switches [10], medical imaging devices [11][12][13], exoskeleton rehabilitation robots [14,15], solar centralizing mirrors [16,17], millirobots [18], microrobots [19][20][21], and soft robots [22][23][24][25]. Some investigators use discrete actuators in hyper-redundant manipulators [2,[26][27][28][29].…”

Design and simulation analysis of impact-resistant flexible drill pipe for rock-breaking rig

“…In recent years, taking into account, the series elastic actuator (SEA) has the advantages of low impedance, high energy density, good stability, shock resistance, and vibration reduction and has attracted wide attention from domestic and foreign scholars. [7][8][9][10][11] It is widely used in industrial robots, [12][13][14] medical rehabilitation, [15][16][17][18] energy utilization, 19,20 and other fields. Among them, Irmscher et al 21 designed a lightweight and compact torsion spring and used it in an auxiliary orthosis for sports-impaired stroke patients.…”

Modeling and Control of Four-bar Mechanism with Series Elastic Actuators

“…There are several physical implementations of the elements that connect the motor and the link, as discussed in (Lin et al, 2017;Leal-Junior et al, 2018;Cummings et al, 2016), where a rigid element with specific geometry can achieve the desired deflection. In Cappello et al (2019), e.g., a compliant element with multiple equilibrium positions is presented for use in assistive robotics. In addition to these, Jarrett and McDaid (2019); Kim and Oh (2019); Kakogawa and Ma (2018) feature elastomers performing the spring function.…”