13 accepted papers
Many applications require robotic end-effectors and mechanisms to move along periodic trajectories of given amplitude and frequency. If motion parameters are known in advance, it might be beneficial to design the mechanism in such a way that its natural frequency is close to that of the desired traj
Twisted string actuators (TSA) are efficient, compliant cable actuators with high power density that have found their way into many engineering and robotics applications in recent years. They are generally used in the scenarios involving comparatively slow positioning, since quick motions in TSAs of…
This letter presents derivation and experimental evaluation of extended dynamical model of twisted string actuator (TSA). The proposed model supports more precise estimation of required motor torque for both low-speed and high-speed (up to 2 Hz) motion by considering effects of elastic deformation o
This paper presents a study on a compliant cable-driven exoskeleton for hip assistance in lifting tasks that is aimed at preventing low-back pain and injuries in the vocational setting. In the proposed concept, we used twisted string actuator (TSA) to design a light-weight and powerful exoskeleton t…
This study proposes a technique to estimate the output state of twisted string actuators (TSAs) based on payload's acceleration measurements. We outline differential kinematics relationships of the actuator, re-formulate these into a nonlinear parameter identification problem and then apply lineariz…
This paper studies an effect of vibration on twisted string actuation through conduit at high bending angles. In our previous work [1], we have demonstrated that twisted string actuators can be used to transmit power even at significant deflection angles of the conduit. However, several undesirable…
Twisted string actuators are an emerging type of transmission systems that may benefit various applications of robotics and mechatronics. However, control of TSAs in applications that require high bandwidth has attracted comparatively little interest from research community, mainly due to complexity…
In this letter, we proposed a variable radius pulley (VRP) to linearize input-output behavior of twisted string actuators (TSAs). With the help of a VRP, it is possible to make the inherently nonlinear transmission ratio of twisted string constant. This enables design of bidirectional transmission s
Robotic systems for object handling and manipulation are hugely important for modern engineering and industry, with their efficiency, agility and robustness often depending on gripper design and performance. In this work, we investigate a gripper design that, when driven by a twisted string actuator…
Twisted string actuators (TSAs) are gaining popularity in modern engineering and robotic applications. However, in conventional actuators of this type, the twisted part of the string should not be in contact with any surfaces or objects because this may interfere with the propagation of twisting. Th…
Twisted string actuators are widely used in different areas of robotics, however, their lifetime remains one of the main concerns for robotics. There are no comprehensive studies that relate the lifetime of a twisted string to its material properties and operation conditions, which can be important…
The twisted string actuator is an actuator that is gaining popularity in various engineering and robotics and applications. However, the fundamental limitation of actuators of this type is the uni-directional action, meaning that the actuator can contract but requires external power to return to its…
Actuators with adjustable transmission ratios are required in a variety of robotics and automation applications, spanning from human assistive devices and mobile robots to general manipulators. Most existing self-adjustable actuators are bulky and mechanically complex, which often makes their implem…