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In this paper, an ongoing work for verifying the behavior of a twisted string actuator in contact with a sliding surface or guided through a sheath is presented. The twisted string actuation system is particularly suitable for very compact and light-weight robotic devices, like artificial limbs and exoskeletons, since it allows the implementation of powerful tendon-based driving systems, based on...
Robots with Variable Stiffness Actuators (VSA) are intrinsically flexible in the joints. The built-in mechanical spring has the advantage of a higher peak performance, in some extend increased safety for humans interacting physically with the robot, and promises a more energy efficient robot for certain trajectories. This paper shows the modeling process of a VSA including energy losses on the example...
Dynamic modeling and control of planar parallel cable robot with considering elastic and inertia effects of cables and pulley dynamic consideration in final equation of motion is calculated in this paper. In this paper, planar parallel cable robot has four cables, demonstrate one degree of actuation redundancy. More perfect dynamic equation of cable robot is derived that contains end-effector, cable,...
Obtaining a dynamic model for the parallel mechanism is always regarded as a challenging process due to high complexity of the dynamic equations especially in presence of friction. In this paper the process of black-box identification of friction and rigid-body dynamics of an overconstrained 3-DOF decouple mechanism is addressed. Since the under study mechanism is an overconstrained parallel mechanism,...
In this paper, a recently proposed assistive controller, called output feedback assistive control method (OFAC), is applied to a single axis stage. The OFAC method employs inherent properties of series elastic actuators (SEAs) to provide assistance to compliantly actuated systems without requiring any information about contact forces, systems accelerations or their future paths. Therefore, there is...
Nowadays, exoskeletons have been gaining popularity due to their potential use in rehabilitation and augmentation. These robots often utilize series elastic actuators to facilitate compliant interaction with the human. Numerous studies have been carried out with the purpose of identification and control of these type of actuators. The goal of this paper is to provide a method for dynamic modeling...
Over the past decade, pneumatic muscle actuator (PMA) has been in the limelight and receiving much attention not only in the field of industrial application as well as in prominent research areas such as robotics and biomedical engineering. The uprising can be accorded to the many advantages that PMA offers such as inherent compliant safety, low maintenance and powerful. However, PMA has yet to emerge...
Series elastic actuators (SEAs) are commonly used in rehabilitation devices and biped robots to satisfy constraints in terms of safety, impact tolerance, energy storing, and force controllability. This paper discusses the novel design of a multifunctional elastic actuator (MFEA). Our design has several modes with different compliance functionalities (linear and nonlinear force-deflection profiles)...
This paper presents the design of cascade controller for robotic fingers designed based on an anthropomorphic inspiration. These fingers are driven by Pneumatic Artificial Muscle actuators. The high nonlinear dynamics of these actuators and the inherent hysteresis in their behavior lead to the modelling and control problems that cause a lack of robustness in the hand's performance. The actuator has...
Shape Memory Alloy (SMA) can be used as actuators in different robotic systems. Small size and weight of SMA springs make them appropriate for micro robotic devices such as surgery grippers. In this paper, a novel gripper actuated by SMA springs is designed and fabricated. Both closing and opening of the gripper's jaws is produced by a SMA spring which is actuates by applying voltage. A Fan is also...
Traditional elastic actuator is the flexible structure which needed to connected to the output shaft of the brake. Besides, according to the principle of the state of the connection, it could be divided into series elastic actuators (SEA), as well as parallel elastic actuator (PEA) [3]. Therefore, the brake output has a certain flexibility, providing compliance or shock absorption, and other functions...
This paper presents “ROVBus,” a communications framework tailored to custom ROV development, that enables plug-and-play interconnection of various component tools via a unified communications bus. The flexibility provided by this approach enables easy custom tooling for various ROV frameworks and allows them to be tailored to a range of applications. The paper will describe the ROVBus system architecture...
In this paper, adaptive neural network control is proposed for a robotic exoskeleton that contains unknown parameters in its dynamic. Neural networks are used to compensate for the unknown deadzone effect caused by the actuators and the unknown dynamics of the robot. State-feedback control is proposed and a disturbance observer is then designed to estimate the unknown disturbance. Radial Basis Function...
This paper presents a novel self-aligning knee mechanism for walking assistance devices for the elderly to provide physical gait assistance. Self-aligning knee joints can assist in flexion/extension motions of the knee joint and compensate the knee's transitional movements in the sagittal plane. In order to compensate the center of rotation, which moves with the flexion/extension motion of the human...
The following article presents our attempt to design and build a simple, low-cost, impedance controlled, multifinger gripper having two phalanges in each finger. The paper discusses two different approaches of creating its mechanical construction, comparing the strengths and weaknesses of both solutions, as well as electronic design and software architecture of the controller. The results of basic...
The aim of this paper is to describe the design of a soft, wearable glove for power assisted and rehabilitation, based on pneumatic soft actuators. The extensor bending type of pneumatic soft actuators was used in this study, which proved these actuators are appropriate by examining their characteristics. A proposed solution for a release movement is presented. Experimental results show this solution...
In this paper, we present Tri-SedimentBot (TSB), an underwater sediment sampling robot that uses combined rotation and linear motion to collect sediment. A main contribution of this system is a novel design for the sampling system that employs a dual-motion system with feedback control in order to maintain the stability of the TSB and the sediment collection method. We demonstrate the performance...
For lower-limb power-assist exoskeleton, following the motion of human smoothly requires that the motion ranges of related joints are in coincident with the characteristics of human motion. The knee and hip joints bend at maximum angle when doing deep squat, which is a significant case for exoskeleton research. In this paper, we introduce a slider-crank mechanism to handle the problem of unachievable...
The wear and fatigue life of actuators is a topic of great interest in the field of Industrial Automation since linear actuators are essential components to many machine tools and robots. The fatigue life of a linear actuator closely relates to many factors such as loads lubrication, material properties, surface properties, pressure, and temperature. Therefore, the fatigue life cannot be modeled without...
Power-efficient fluidic driven system is beneficial to extending the working time of autonomous and wearable soft robots supplied by independent power sources such as batteries. In this paper, an energy recovery scheme is proposed to reutilize the pressurized air released by retracting pneumatic soft actuators instead of venting to atmosphere. The scheme's novelty lies in an air accumulator employed...
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