Posts Tagged grasping
[Abstract] Design and Test of a Closed-Loop FES System for Supporting Function of the Hemiparetic Hand Based on Automatic Detection using the Microsoft Kinect sensor
[ARTICLE] The Robotic Sixth Finger: a Wearable Compensatory Tool to Regain Grasping Capabilities in Paretic Hands – Full Text PDF
Among the most promising field of applications of wearable robotics there are the rehabilitation and the support in activities of daily living (ADL) of impaired people. In this paper, we propose two possible designs of a robotic extra-finger, the Robotic Sixth Finger, for grasping compensation in patients with reduced hand mobility, such as post-stroke patients. The idea is to let the patients be able to grasp an object by taking advantage of the wearable device worn on the paretic limb by means of an elastic band. The Robotic Sixth Finger and the paretic hand work jointly to hold an object. Adding a robotic opposing finger is a promising approach that can significantly improve the grasping functional compensation in different typologies of patients during everyday life activities.
Wearable robots are expected to work very closely, to interact and collaborate with people in an intelligent environment . Traditionally, wearable robotic structures have been mainly used in substitution of lost limbs (e.g., prosthetic limbs) or for human limb rehabilitation (e.g., exoskeletons). However, the progress in miniaturization and efficiency of the technological components is allowing more light and compact solutions, enhancing user’s safety and comfort, while opening new opportunities for wearable robot use . Together with exoskeleton and prosthesis, a very promising research direction seems to be that of adding robotic limbs to human, rather than substituting or enhancing them . This addition could let the humans augment their abilities and could give support in everyday tasks to impaired people. This paper investigates how to compensate the capabilities of the human hand, instead of developing additional robotic extra-arms, as discussed for instance in . The idea of using an extra-finger to support the human hand in grasping functions was initially proposed in . Then, independently both in  and [7, 8], the authors proposed the use of extra fingers to support the human hand to grasp objects whose size does not fit a hand or in executing bimanual tasks with one hand. The main difference is that in [7, 8], the goal was to minimize the size and the weight of the unique extra limb, while in , two extra fingers were used so to hold objects. While in  the authors developed a control strategy to grasp and manipulate objects, in  the authors mainly focused on the use of extra fingers for post-stroke patients.
Focusing on the hand, many wearable devices have been proposed in the last decade, especially for hand rehabilitation and function recovery. A review on robotassisted approaches to motor neurorehabilitation can be found in . In  the authors presented a comprehensive review of hand exoskeleton technologies for rehabilitation and assistive engineering, from basic hand biomechanics to actuator technologies.
However, most of the devices proposed in literature are designed either to increase the functional recovery in the first months of the rehabilitation therapy, when biological restoring and reorganization of the central nervous system take place, or are designed to augment human hand capabilities of healthy subjects by coordinating the device motion to that of the hand.
To the best of our knowledge, only few works target on the robotic compensation of hand function in the latter phase of rehabilitation. This means that patients usually after 6–9 months of rehabilitation must rely only on compensatory strategies by improving adaptations that increase the functional disparity between the impaired and the unaffected upper limb .
This work focuses on the compensation of hand function in patients with paretic limbs, e.g. chronic stroke patients. The final aim is to provide the patient with an additional robotic finger worn on the wrist. The Robotic Sixth Finger is used together with the paretic hand to seize an object, as shown in Fig. 1. The systems acts like a two-finger gripper, where one finger is represented by the Robotic Sixth Finger, while the other by the patient paretic limb. The proposed device goes beyond exoskeletons: it adds only what is needed to grasp, i.e. an extra thumb. We presented in  a preliminary version of a robotic extra-finger showing how this wearable device is able to enhance grasping capabilities and hand dexterity in healthy subjects. In , we also presented an object-based mapping algorithm to control robotic extra-limbs without requiring explicit commands by the user. The main idea of the mapping was to track human hand by means of dataglove and reproduce the main motions on the extra-finger. This kind of approach is not suitable for patients with a paretic limb due to the reduced mobility of the hand. Therefore, we developed a wearable interface embedded in a ring to activate and use the finger .
In this work, we propose two possible designs of devices. The first model is a modular fully actuated finger. The other design consists of an underactuated finger which is compliant and consequently able to adapt to the different shapes of the objects.
For validation purposes, pilot experiments with two chronic stroke patients were performed. The experiments consisted in wearing the Robotic Sixth Finger and performing a rehabilitation test referred to as Frenchay Arm Test [15, 10]. Finally, we present preliminary results on the use of the extra-fingers for grasping objects for Activities of Daily Living (ADL).
[Abstract] The Soft-SixthFinger: a Wearable EMG Controlled Robotic Extra-Finger for Grasp Compensation in Chronic Stroke Patients. – IEEE Xplore
This paper presents the Soft-SixthFinger, a wearable robotic extra-finger designed to be used by chronic stroke patients to compensate for the missing hand function of their paretic limb. The extra-finger is an underactuated modular structure worn on the paretic forearm by means of an elastic band. The device and the paretic hand/arm act like the two parts of a gripper working together to hold an object. The patient can control the flexion/extension of the robotic finger through the eCap, an Electromyography-based (EMG) interface embedded in a cap. The user can control the device by contracting the frontalis muscle. Such contraction can be achieved simply moving his or her eyebrows upwards. The Soft-SixthFinger has been designed as tool that can be used by chronic stroke patients to compensate for grasping in many Activities of Daily Living (ADL). It can be wrapped around the wrist and worn as a bracelet when not used. The light weight and the complete wireless connection with the EMG interface guarantee a high portability and wearability. We tested the device with qualitative experiments involving six chronic stroke patients. Results show that the proposed system significantly improves the performances of the patients in the proposed tests and, more in general, their autonomy in ADL.
[ARTICLE] Kinematic analysis of upper limb motion: Feasibility, preliminary results in controls and hemiparetic subjects, prospects
The aim of this study is to develop a valid and standardized instrumental analysis of upper limb (UL) motion in stroke patients.
Sixteen controls and 15 hemiparetic subjects (mean age = 54 ± 18,2 years old; Fugl-Meyer Upper Limb 41,4 ± 12,4) underwent kinematic motion analysis (passive markers, Optitrack) of pointing and grasping tasks. We examined the ability to perform a single pointing task and three reach-to-grasp tasks: key turning, reaching and grasping a can, reaching and grasping a cube; at a self-selected speed and as fast as possible. Speed, accuracy and efficiency of each movement were quantified and compared between controls and hemiparetic subjects, and between the ipsilateral of control subjects and the affected side; to describe reaching and grasping.
For reaching, movement time of hemiparetic UL was longer, less smooth (peak velocity, jerk), less direct (higher index path ratio) and associated with more trunk compensation (higher trunk/hand ratio). Movement time, jerks and trunk/hand ratio were the most discriminant variables between hemiparetic UL and ipsilateral/control UL, in any task analysed. Trunk displacement was greater in grasping than in reaching tasks. For grapsing tasks, movement time is the most discriminant factor between hemiparetic and control/ipsilateral UL, especially for the key turn task. Movement alterations were also found for ipsilateral limb. Association between kinematic variables and clinical features during reaching time (Fugl-Meyer, MAL, WFMT, ARAT) was greater for the task “grasping a can”.
Our results are similar to those of the literature, but suggest that we have to privilege some of the most relevant kinematic parameters. This standardization phase emerging after a validation phase of the techniques can make the biomechanical analysis of the upper limb as easy and valid as gait analysis and should help to develop the quantified measurement of prehension. This protocol is currently in process to objectively assess the therapeutic effects of rehabilitation treatments (botulinum toxin, induced constraint therapy).
[ARTICLE] A full upper limb robotic exoskeleton for reaching and grasping rehabilitation triggered by MI-BCI
In this paper we propose a full upper limb exoskeleton for motor rehabilitation of reaching, grasping and releasing in post-stroke patients. The presented system takes into account the hand pre-shaping for object affordability and it is driven by patient’s intentional control through a self-paced asynchronous Motor Imagery based Brain Computer Interface (MI-BCI). The developed antropomorphic eight DoFs exoskeleton (two DoFs for the hand, two for the wrist and four for the arm) allows full support of the manipulation activity at the level of single upper limb joint. In this study, we show the feasibility of the proposed system through experimental rehabilitation sessions conducted with three chronic post-stroke patients. Results show the potential of the proposed system for being introduced in a rehabilitation protocol.
This paper presents a novel electromyography (EMG)-driven hand exoskeleton for bilateral rehabilitation of grasping in stroke. The developed hand exoskeleton was designed with two distinctive features:
(a) kinematics with intrinsic adaptability to patient’s hand size,
(b) free-palm and free-fingertip design, preserving the residual sensory perceptual capability of touch during assistance in grasping of real objects.
In the envisaged bilateral training strategy, the patient’s non paretic hand acted as guidance for the paretic hand in grasping tasks. Grasping force exerted by the non paretic hand was estimated in real-time from EMG signals, and then replicated as robotic assistance for the paretic hand by means of the hand-exoskeleton. Estimation of the grasping force through EMG allowed to perform rehabilitation exercises with any, non sensorized, graspable objects.
This paper presents the system design, development, and experimental evaluation. Experiments were performed within a group of 6 healthy subjects and 2 chronic stroke patients, executing robotic-assisted grasping tasks. Results related to performance in estimation and modulation of the robotic assistance, and to the outcomes of the pilot rehabilitation sessions with stroke patients, positively support validity of the proposed approach for application in stroke rehabilitation.
GLOREHA supports upper limb rehabilitation:
- MOBILIZES finger joints: A comfortable and lightweight glove performs all the combinations of joint flexion-extension. If the patient has partial capabilities, he can actively complete his movements.
- STIMULATES neural plasticity: A multi-sensorial stimulation is linked to motor exercises. The therapy includes on screen 3D animation which motivates and involves the patient.
- HELPS THE PATIENT to perform functional exercises: The device leaves the patient’s arm and palm totally free. He can interact with real objects and perform reaching and grasping exercises.
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