1,423 research outputs found
Optimization and design of a cable driven upper arm exoskeleton
This paper presents the design of a wearable upper arm exoskeleton that can be used to assist and train arm movements of stroke survivors or subjects with weak musculature. In the last ten years, a number of upper-arm training devices have emerged. However, due to their size and weight, their use is restricted to clinics and research laboratories. Our proposed wearable exoskeleton builds upon our extensive research experience in wire driven manipulators and design of rehabilitative systems. The exoskeleton consists of three main parts: (i) an inverted U-shaped cuff that rests on the shoulder, (ii) a cuff on the upper arm, and (iii) a cuff on the forearm. Six motors, mounted on the shoulder cuff, drive the cuffs on the upper arm and forearm, using cables. In order to assess the performance of this exoskeleton, prior to use on humans, a laboratory test-bed has been developed where this exoskeleton is mounted on a model skeleton, instrumented with sensors to measure joint angles and transmitted forces to the shoulder. This paper describes design details of the exoskeleton and addresses the key issue of parameter optimization to achieve useful workspace based on kinematic and kinetic models.</jats:p
Comfort-Centered Design of a Lightweight and Backdrivable Knee Exoskeleton
This paper presents design principles for comfort-centered wearable robots
and their application in a lightweight and backdrivable knee exoskeleton. The
mitigation of discomfort is treated as mechanical design and control issues and
three solutions are proposed in this paper: 1) a new wearable structure
optimizes the strap attachment configuration and suit layout to ameliorate
excessive shear forces of conventional wearable structure design; 2) rolling
knee joint and double-hinge mechanisms reduce the misalignment in the sagittal
and frontal plane, without increasing the mechanical complexity and inertia,
respectively; 3) a low impedance mechanical transmission reduces the reflected
inertia and damping of the actuator to human, thus the exoskeleton is
highly-backdrivable. Kinematic simulations demonstrate that misalignment
between the robot joint and knee joint can be reduced by 74% at maximum knee
flexion. In experiments, the exoskeleton in the unpowered mode exhibits 1.03 Nm
root mean square (RMS) low resistive torque. The torque control experiments
demonstrate 0.31 Nm RMS torque tracking error in three human subjects.Comment: 8 pages, 16figures, Journa
A flexible sensor technology for the distributed measurement of interaction pressure
We present a sensor technology for the measure of the physical human-robot interaction pressure developed in the last years at Scuola Superiore Sant'Anna. The system is composed of flexible matrices of opto-electronic sensors covered by a soft silicone cover. This sensory system is completely modular and scalable, allowing one to cover areas of any sizes and shapes, and to measure different pressure ranges. In this work we present the main application areas for this technology. A first generation of the system was used to monitor human-robot interaction in upper- (NEUROExos; Scuola Superiore Sant'Anna) and lower-limb (LOPES; University of Twente) exoskeletons for rehabilitation. A second generation, with increased resolution and wireless connection, was used to develop a pressure-sensitive foot insole and an improved human-robot interaction measurement systems. The experimental characterization of the latter system along with its validation on three healthy subjects is presented here for the first time. A perspective on future uses and development of the technology is finally drafted
An active back-support exoskeleton to reduce spinal loads: actuation and control strategies
Wearable exoskeletons promise to make an impact on many people by
substituting or complementing human capabilities. There has been increasing
interest in using these devices to reduce the physical loads and
the risk of musculoskeletal disorders for industrial workers. The interest
is reflected by a rapidly expanding landscape of research prototypes as
well as commercially available solutions. The potential of active exoskeletons
to reduce the physical loads is considered to be greater compared to
passive ones, but their present use and diffusion is still limited.
This thesis aims at exploring and addressing two key technological
challenges to advance the development of active exoskeletons, namely actuators
and control strategies, with focus on their adoption outside laboratory
settings and in real-life applications. The research work is specifically
applied to a back-support exoskeleton designed to assist repeated manual
handling of heavy objects. However, an attempt is made to generalise the
findings to a broader range of applications.
Actuators are the defining component of active exoskeletons. The greater
the required forces and performance, the heavier and more expensive actuators
become. The design rationale for a parallel-elastic actuator (PEA)
is proposed to make better use of the motor operating range in the target
task, characterized by asymmetrical torque requirements (i.e. large static
loads). This leads to improved dynamic performance as captured by the
proposed simplified model and measures, which are associated to user
comfort and are thus considered to promote user acceptance in the workplace.
The superior versatility of active exoskeletons lies in their potential
to adapt to varying task conditions and to implement different assistive
strategies for different tasks. In this respect, an open challenge is represented
by the compromise between minimally obtrusive, cost-effective
hardware interfaces and extracting meaningful information on user intent
resulting in intuitive use. This thesis attempts to exploit the versatility of
the active back-support exoskeleton by exploring the implementation of
different assistive strategies. The strategies use combinations of user posture
and muscular activity to modulate the forces generated by the exoskeleton.
The adoption of exoskeletons in the workplace is encouraged first of all
by evidence of their physical effectiveness. The thesis thus complements
the core contributions with a description of the methods for the biomechanical
validation. The preliminary findings are in line with previous
literature on comparable devices and encourage further work on the technical
development as well as on more accurate and specific validation
- …