The inherent strength of robotic manipulators can be used to assist humans in performing heavy lifting tasks. These robots reduce manpower, reduce fatigue, and increase productivity. This thesis deals with the development of a control system for a robot being built for this purpose. The task for this robot is to lift heavy payloads while performing complex insertion tasks. This task must be completed on the deck of a naval vessel where possible disturbances include wind, rain, poor visibility, and dynamic loads induced by a swaying deck. The primary objective of the control-ler being designed here is to allow for insertion of the payload despite tight positioning tolerances and disturbances like surface friction, joint friction, and dynamic loads from ship motions. A control struc-ture designed for intuitive interaction between the robot and operator is analyzed and shown to be stable using an established environment interaction model. The controller is shown to perform within established specifications via numerical simulation based on simple user inputs. An additional objective of this con-troller design is to prevent part jamming during the insertion task. With a large, powerful manipulator, the chances of a jam occurring is high. Without the use of bilateral force feedback, it will be difficult for the operator feel when these jams will occur and there will be no information about how to prevent them. This thesis analyzes the geometry and mechanics of the jamming problem and derives a control system to assist the user in preventing these jams. These methods can be extended to other insertion tasks simply by specifying the appropriate geometry.

(далее…)

Категория: Научные статьи | Нет комментариев »

This paper presents a hand rehabilitation support system for self-performing rehabilitation therapies. The developed system consists of hand exoskeleton device, which provides individual finger joint motion for disabled persons, and a lateral symmetric master-slave motion assistant system joined with virtual reality (VR) environment. Most of disability caused by CVA (Cerebral Vascular Accident) or bone fracture are hemiplegia where impaired hand is only in one side. Based on the peculiarity of this disability, we adopted a symmetric master-slave motion assistant system in which the impaired hand is driven by the healthy hand in the opposite side.

(далее…)

Категория: Научные статьи | Нет комментариев »

There is a need for wearable powered upper limb exoskeletons able to apply forces to the upper limb for use by people with disabilities and/or limb weakness or injury. The robotic exoskeleton called WOTAS (Wearable Orthosis for Tremor Assessment and Suppression) presented in this paper will provide a means of testing non-grounded control strategies in order to help these people. For instance, biomechanical loading, in particular, viscous loading of the upper limb has been proposed in the literature as a means for suppressing pathologic tremor. This article describes in detail the general concept for WOTAS, outlining the special features of the design and selection of system components.

(далее…)

Категория: Научные статьи | Нет комментариев »

Our experience with a Haptic Workstation™ has shown that this device is uncomfortable to use during long sessions. The main reason is the uncomfortable posture of the arms, which must be kept outstretched horizontally while supporting the weight of an exoskeleton. We describe Zero-G, a real-time weight compensation system aimed at improving user comfort by compensating for the weight of both the exoskeleton and arms (zero gravity illusion). We present experimental results complemented with electro myography measures (EMG) as an indicator of muscular activity/fatigue. Our tests show how Zero-G exerts a positive influence on the reduction of muscular fatigue when using a Haptic Workstation™.

(далее…)

Категория: Научные статьи | Нет комментариев »

The paper presents the mechanical design of the L-EXOS, a new exoskeleton for the human arm. The exoskeleton is a tendon driven wearable haptic interface with 5 dof 4 actuated ones, and is characterized by a workspace very close to the one of the human arm. The design has been optimized to obtain a solution with reduced mass and high stiffness, by employing special mechanical components and carbon fiber structural parts. The devised exoskeleton is very effective for simulating the touch by hand of large objects or the manipulation within the whole workspace of the arm. The main features of the first prototype that has been developed at PERCRO are presented, together with an indication of the achieved and tested performance.

(далее…)

Категория: Научные статьи | Нет комментариев »