DTEA: 双拓扑弹性致动器实现实时在串联与并联顺应间切换

Jul 16, 2026

Series and parallel elastic actuators provide complementary strengths but lack a mechanism for switching between topologies during operation. This paper introduces a Dual-Topology Elastic Actuator (DTEA) that enables dynamic transition between SEA and PEA compliance states in real time. A prototype demonstrates feasibility, while experiments quantify switching robustness and timing. The actuator completes 324 switching cycles under load without damage, achieving under 33.33 ms switching time. Tests further compare stiffness and disturbance rejection across modes.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages8

Reading Time20 min

Introduction

Series Elastic Actuators (SEA)

Parallel Elastic Actuators (PEA)

Motivation for Real-Time Topology Switching

Related Work and Key Gap

DTEA: A Dual-Topology Elastic Actuator Enabling Real-Time Switching Between Series and Parallel Compliance Vishal Ramesh 1 , Aman Singh2 , and Shishir Kolathaya2 arXiv :2604 . 15865v2 [ cs .RO] 11 Jul 2026 Abstract—Series and parallel elastic actuators offer complementary but mutually exclusive advantages, yet no existing actuator enables real-time transition between these topologies during operation. This paper presents a novel actuator design called the Dual-Topology Elastic Actuator (DTEA), which enables dynamic switching between SEA and PEA topologies during operation. A proof-of-concept prototype of the DTEA is developed to demonstrate the feasibility of the topology-switching mechanism. Experiments are conducted to evaluate the robustness and timing of the switching mechanism under operational conditions. The actuator successfully performed 324 topologyswitching cycles under load without damage, demonstrating the robustness of the mechanism. The measured switching time between SEA and PEA modes is under 33.33 ms. Additional experiments are conducted to characterize the static stiffness and disturbance rejection performance in both SEA and PEA modes. Static stiffness tests show that the PEA mode is 1.53 × stiffer than the SEA mode, with KSEA = 5 .57±0 .02Nm/rad and KPEA = 8 .54 ± 0.02Nm/rad. Disturbance rejection experiments show that the mean peak deflection in SEA mode is 2.26 × larger than in PEA mode (5 .2◦ vs. 2.3◦), while the mean settling time is 3.45 × longer (1380 ms vs. 400ms). The observed behaviors are consistent with the known characteristics of conventional SEA and PEA actuators, validating the functionality of both modes in the DTEA actuator. Index Terms—Actuation and Joint Mechanisms; Mechanism Design; Engineering for Robotic Systems; Series Elastic Actuators; Parallel Elastic Actuators; Topology switching; I. INTRODUCTION Compliant actuation is central to robots that interact with unstructured environments and humans. The Series Elastic Actuator (SEA) [1] places a spring between motor and load, reducing interface stiffness while enabling shock tolerance, low reflected inertia, force estimation from deflection, and energy storage. SEAs are widely used in exoskeletons [2] and legged robots [3] . However, all load torque passes through the spring, causing continuous I2R losses even in quasi-static postures. The Parallel Elastic Actuator (PEA) addresses this limitation by placing the spring between the actuator housing and the output, directly coupling the elastic element in parallel with the motor. When tuned to the dominant static load, the spring passively compensates gravity, reducing energy consumption by up to 78–80%[4], [5] . This energy advantage has motivated PEA adoption in prosthetic ankles [6], This research is supported by ARTPARK at IISc. 1Vishal Ramesh is with the Department of Cyber-Physical Systems (CPS), Indian Institute of Science (IISc), Bengaluru, India, and the Indian Institute of Information Technology, Hyderabad, [India.](India. vishal0905@berkeley.edu)[ vishal0905@berkeley.edu](India. vishal0905@berkeley.edu) 2Aman Singh and Shishir Kolathaya are with the Department of CyberPhysical Systems (CPS), Indian Institute of Science (IISc), Bengaluru, India.{saman, [shishirk](shishirk}@iisc.ac.in)[}](shishirk}@iisc.ac.in)[@iisc.ac.in](shishirk}@iisc.ac.in) Fig. 1. DTEA: Exploded view of Dual-Topology Elastic Actuator prototype, an actuator that switches between SEA and PEA modes during operation. bipedal robots [7], and exoskeletons [8] . However, the spring torque is rigidly coupled to the joint angle, meaning the motor must work against the spring for any motion away from equilibrium, making PEAs ill-suited for large range-ofmotion tasks. The question of which topology is energetically superior has no universal answer. Verstraten et al. [4] demonstrated that the crossover between SEA and PEA efficiency depends on gravitational offset and spring tuning, Beckerle et

FAQs

What problem does the DTEA address?

Existing elastic actuator designs offer SEA and PEA advantages but do not enable real-time transitions between these topologies during operation. DTEA provides dynamic switching between SEA and PEA compliance states while running.

How was the DTEA switching mechanism validated?

A proof-of-concept prototype was built, and experiments evaluated switching robustness and timing under operational conditions, including load testing and repeated switching cycles.

What were the key performance results when switching between SEA and PEA?

The actuator executed 324 topology-switching cycles under load without damage, with a measured SEA-to-PEA switching time under 33.33 ms. Mode comparisons also show PEA is stiffer than SEA, while disturbance rejection behavior differs by mode.

Jul 16, 2026

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