The CompActTM actuator features a clutch mechanism placed in parallel with its passive series elastic transmission element and can therefore benefit from the advantages of both series elastic actuators (SEA) and rigid actuators. The actuator is capable of effectively managing the storage and release of the potential energy of the compliant element by the appropriate control of the clutch subsys...

Continuous soft robots are becoming more and more widespread in applications, due to their increased safety and flexibility in critical applications. The possibility of having soft robots that are able to change their stiffness in selected parts can help in situations where higher forces need to be applied. This paper describes a theoretical framework for learning the desired stiffness characte...

Modern machine tools based on parallel kinematic architecture provide excellent performance in terms of stiffness/weight ratio. Also, hydraulic actuators are widely used in industrial applications due to several advantages like large force and torque, high power to weight ratio, rapid response. The current paper presents the mechatronic design of a translational 3-DOF parallel robot which uses ...

It has been shown that humans are able to selectively control the endpoint impedance of their arms when moving in an unstable environment. However, directional instability was only examined for the case in which the main contribution was from coactivation of biarticular muscles. The goal of this study was to examine whether, in general, the CNS activates the sets of muscles that contribute to s...

This research aims at developing a magnetic resonance (MR)-compatible equivalent of an exoskeleton used for wrist movement rehabilitation therapy of neurological patients. As a crucial step towards the accomplishment of this goal, this paper investigates the development of a novel actuation architecture suitable for interaction control in MR environments, the MR-SEA (SEA stands for Series Elast...

It is widely recognised that compliant actuation is advantageous to robot control once dynamic tasks are considered. However, the benefit of intrinsic compliance comes with high control complexity. Specifically, coordinating the motion of a system through a compliant actuator and finding a task-specific impedance profile that leads to better performance is known to be non-trivial. Here, we prop...

This study is concerned with a new adaptive impedance control strategy to compensate for unknown time-varying environment stiffness and position. The uncertainties are expressed by Function Approximation Technique (FAT), which allows the update laws to be derived easily using Lyapunov stability theory. Computer simulation results are presented to validate the effectiveness of the proposed strat...

This study presents resonance-based control methods proposed by the authors for multi-joint robots. The proposed control methods adjust stiffness of mechanical elements installed in each joint of the robots to minimize actuator torque while generating desired periodic motions. Some of these control method adjust not only stiffness but also motion patterns to reduce further actuator torque. Adva...

Background: People with knee osteoarthritis have a low quality of life due to joint pain and stiffness that severely limits their daily activities.  This study aims to investigate the impact of self-acupressure on the pain, joint stiffness and physical functioning of patients with osteoarthritis. Methods: This randomized clinical trial was conducted on 78 patients aged 50 to 70 years with knee...

Diplomingenieur (Dipl.-Ing.) The DLR Hand-Arm-System is the first component of a new humanoid robot which is as robust and anthropomorphic as possible. Each joint of the system has an adjustable spring mechanism, which enables to adjust the mechanical stiffness. Additionally, the springs increase the mechanical robustness of the system against impacts. In this thesis the compliance control of t...