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At least 937 records · Page 52Linked to original sources

PubMed2005

Design of a robotic gait trainer using spring over muscle actuators for ankle stroke rehabilitation.

Repetitive task training is an effective form of rehabilitation for people suffering from debilitating injuries of stroke. We present the design and working concept of a robotic gait trainer (RGT), an ankle rehabilitation device for assisting stroke patients during gait. Structurally based on a tripod mechanism, the device is a parallel robot that incorporates two pneumatically powered, double-acting, compliant, spring over muscle actuators as actuation links which move the ankle in dorsiflex ion/plantarflexion and inversion/eversion. A unique feature in the tripod design is that the human anatomy is part of the robot, the first fixed link being the patient's leg. The kinematics and workspace of the tripod device have been analyzed determining its range of motion. Experimental gait data from an able-bodied person wearing the working RGT prototype are presented.

Ankle Joint↗

PubMed2005

Efficient bipedal robots based on passive-dynamic walkers.

Passive-dynamic walkers are simple mechanical devices, composed of solid parts connected by joints, that walk stably down a slope. They have no motors or controllers, yet can have remarkably humanlike motions. This suggests that these machines are useful models of human locomotion; however, they cannot walk on level ground. Here we present three robots based on passive-dynamics, with small active power sources substituted for gravity, which can walk on level ground. These robots use less control and less energy than other powered robots, yet walk more naturally, further suggesting the importance of passive-dynamics in human locomotion.

Algorithms↗

PubMed2003

Modeling and production of robot trajectories using the Temporal Parametrized Self Organizing Maps.

In this paper we proposed an unsupervised neural architecture, called Temporal Parametrized Self Organizing Map (TEPSOM), capable of learning and reproducing complex robot trajectories and interpolating new states between the learned ones. The TEPSOM combines the Self-Organizing NARX (SONARX) network, responsible for coding the temporal associations of the robotic trajectory, with the Parametrized Self-Organizing (PSOM) network, responsible for an efficient interpolation mechanism acting on the SONARX neurons. The TEPSOM network is used to model the inverse kinematics of the PUMA 560 robot during the execution of trajectories with repeated states. Simulation results show that the TEPSOM is more accurate than the SONARX in the reproduction of the learned trajectories.

Algorithms↗

PubMed2006

Manifold learning for robot navigation.

In this paper we introduce methods to build a SOM that can be used as an isometric map for mobile robots. That is, given a dataset of sensor readings collected at points uniformly distributed with respect to the ground, we wish to build a SOM whose neurons (prototype vectors in sensor space) correspond to points uniformly distributed on the ground. Manifold learning techniques have already been used for dimensionality reduction of sensor space in navigation systems. Our focus is on the isometric property of the SOM. For reliable path-planning and information sharing between several robots, it is desirable that the robots build an internal representation of the sensor manifold, a map, that is isometric with the environment. We show experimentally that standard Non-Linear Dimensionality Reduction (NLDR) algorithms do not provide isometric maps for range data and bearing data. However, the auxiliary low dimensional manifolds created can be used to improve the distribution of the neurons of a SOM (that is, make the neurons more evenly distributed with respect to the ground). We also describe a method to create an isometric map from a sensor readings collected along a polygonal line random walk.

Artificial Intelligence↗

PubMed1999

Integrating neuromorphic action-oriented perceptual inputs to generate a navigation behaviour for a robot.

We use neural networks with pointer map architectures to provide simple attentional processing in a robotic task. A pointer map comprises a map of neurons that encode a stimulus. Besides global feedback inhibition, the map receives feedback excitation via a small group of pointer neurons that encode the location of a salient stimulus on the map as a vectorial representation. The pointer neurons are able to apply selective processing to a particular region of the network. The robot uses these properties to manoeuver in relation to an attended object. We implemented a controller composed of two pointer maps, and a motor map. The first pointer map reports the direction of a salient obstacle in a one-dimensional map of distance derived from infrared sensors. The second pointer map reports the direction to potential obstacles in a two-dimensional edge-enhanced image derived from a forward looking CCD-camera. These outputs are applied to a motor map, where they bias the motor control signals issued to the robots wheels, according to navigational intentions.

Avoidance Learning↗

PubMed2002

Robotically driven interventions: a method of using CT fluoroscopy without radiation exposure to the physician.

Radiation exposure to physicians' hands during interventional procedures with computed tomography (CT) fluoroscopic guidance may be high. A robot was developed that could hold, orient, and advance a needle, with CT fluoroscopic guidance. This robot could be either computer or joystick controlled. Twenty-three robotically guided percutaneous interventions were performed without complication. Physician radiation exposure was negligible during the CT fluoroscopy-guided procedures.

Aged↗

PubMed2002

The rat lumbosacral spinal cord adapts to robotic loading applied during stance.

Load-related afferent information modifies the magnitude and timing of hindlimb muscle activity during stepping in decerebrate animals and spinal cord-injured humans and animals, suggesting that the spinal cord mediates load-related locomotor responses. In this study, we found that stepping on a treadmill by adult rats that received complete, midthoracic spinal cord transections as neonates could be altered by loading the hindlimbs using a pair of small robotic arms. The robotic arms applied a downward force to the lower shanks of the hindlimbs during the stance phase and measured the position of the lower shank during stepping. No external force was applied during the swing phase of the step. When applied bilaterally, this stance force field perturbed the hindlimb trajectories so that the ankle position was shifted downward during stance. In response to this perturbation, both the stance and step cycle durations decreased. During swing, the hindlimb initially accelerated toward the normal, unperturbed swing trajectory and then tracked the normal trajectory. Bilateral loading increased the magnitude of the medial gastrocnemius electromyographic (EMG) burst during stance and increased the amplitude of the semitendinosus and rectus femoris EMG bursts. When the force field was applied unilaterally, stance duration decreased in the loaded hindlimb, while swing duration was decreased in the contralateral hindlimb, thereby preserving interlimb coordination. These results demonstrate the feasibility of using robotic devices to mechanically modulate afferent input to the injured spinal cord during weight-supported locomotion. In addition, these results indicate that the lumbosacral spinal cord responds to load-related input applied to the lower shank during stance by modifying step timing and muscle activation patterns, while preserving normal swing kinematics and interlimb coordination.

Adaptation, Physiological↗

PubMed2003

Use of the NeuroMate stereotactic robot in a frameless mode for movement disorder surgery.

BACKGROUND/AIMS: To evaluate the use of the NeuroMate stereotactic robot with a novel ultrasound registration system for movement disorder surgery (MDS). METHODS: Using the robot in a frameless mode, 51 patients underwent MDS. Surgical planning was carried out using MRI data obtained more than 24 h before surgery. RESULTS: 37 out of 50 targets in the subthalamic nucleus were satisfactorily identified with a single microelectrode trajectory and the final electrode positions were at a mean distance of 1.7 mm from the calculated target. There was a significant improvement in motor scores of the Unified Parkinson's Disease Rating Scale III (off medication) at 6 (43%) and 18 months (51.7%) compared to pre-operative scores (p < 0.05). CONCLUSIONS: The frameless robot using only MRI data can be used for MDS. The temporal separation of imaging from the surgical procedure provides additional time for detailed image analysis and planning.

Humans↗

PubMed1990

Development of a new microsurgical robot for stereotactic neurosurgery.

The robot technology was introduced into a new stereotactic neurosurgery system for applications to biopsy, blind surgery, and functional neurosurgery. The authors have developed a newly designed prototype microsurgical robot, designed to allow a biopsy needle to reach the target such as a cerebral tumor within a brain automatically on the basis of the X, Y, and Z coordinates obtained by CT scanner. This robot is so small that it can be driven in a CT scanner gantry. It consists mainly of the link mechanism and the insertion mechanism. We constructed the link mechanism and investigated its working space.

Biopsy, Needle↗

PubMed2007

Effects of locomotion training with assistance of a robot-driven gait orthosis in hemiparetic patients after stroke: a randomized controlled pilot study.

BACKGROUND AND PURPOSE: The success of gait rehabilitation after stroke depends on active walking exercises. However, the disabling after-effects of stroke often make such exercises impossible at the onset of therapy. To facilitate treadmill training of paraparetic patients, a robot-driven gait orthosis (Lokomat) was developed. We investigated the effects of the Lokomat when used with hemiparetic patients. METHODS: The authors conducted a randomized, controlled pilot study of 30 acute stroke survivors. The treatment group received 30 minutes of robotic training daily and the control group 30 minutes of conventional physiotherapy daily in addition to 30 minutes of conventional physiotherapy for each group. Outcome measures were independence of gait, gait speed, gait parameters, and body tissue composition. RESULTS: After 4 weeks of therapy, the walking ability of the Lokomat group and the control group expressed as the functional ambulation classification was significantly improved. The functional ambulation category (median+/- interquartile range) was at baseline 0+/-0 in control and 0+/-1 in the therapy group and increased after therapy to 1+/-3 in both groups significantly (P=0.01). There was no significant difference in gain of these parameters between the groups. The Lokomat group had a significantly longer single stance phase (sec; mean+/-SEM) on the paretic leg when walking on the floor. At baseline, it was 0.19+/-0.17 and after therapy 0.49+/-0.07 (P=0.014). The control group had increased their body weight approximately 1.33+/-1.40 kg (mean+/-SEM; P=0.046), mostly as fat mass, whereas the Lokomat group had lost fat mass approximately -2.9+/-1.0 kg (mean+/-SEM; P=0.016) and increased their muscle mass approximately 3.36+/-1.4 kg (mean+/- SEM; P=0.031). CONCLUSIONS: This pilot study indicates that Lokomat therapy is a promising intervention for gait rehabilitation. Although there was no difference between groups in gain of functional scores, the Lokomat group showed an advantage of robotic training over conventional physiotherapy in improvement of gait abnormality and body tissue composition.

Aged↗

PubMed2001

Evolution of adaptive synapses: robots with fast adaptive behavior in new environments.

This paper is concerned with adaptation capabilities of evolved neural controllers. We propose to evolve mechanisms for parameter self-organization instead of evolving the parameters themselves. The method consists of encoding a set of local adaptation rules that synapses follow while the robot freely moves in the environment. In the experiments presented here, the performance of the robot is measured in environments that are different in significant ways from those used during evolution. The results show that evolutionary adaptive controllers solve the task much faster and better than evolutionary standard fixed-weight controllers, that the method scales up well to large architectures, and that evolutionary adaptive controllers can adapt to environmental changes that involve new sensory characteristics (including transfer from simulation to reality and across different robotic platforms) and new spatial relationships.

Computer Simulation↗

PubMed1998

Evolutionary body building: adaptive physical designs for robots.

Creating artificial life forms through evolutionary robotics faces a "chicken and egg" problem: Learning to control a complex body is dominated by problems specific to its sensors and effectors, while building a body that is controllable assumes the pre-existence of a brain. The idea of coevolution of bodies and brains is becoming popular, but little work has been done in evolution of physical structure because of the lack of a general framework for doing it. Evolution of creatures in simulation has usually resulted in virtual entities that are not buildable, while embodied evolution in actual robotics is constrained by the slow pace of real time. The work we present takes a step in addressing the problem of body evolution by applying evolutionary techniques to the design of structures assembled out of elementary components that stick together. Evolution takes place in a simulator that computes forces and stresses and predicts stability of three-dimensional brick structures. The final printout of our program is a schematic assembly, which is then built physically. We demonstrate the functionality of this approach to robot body building with many evolved artifacts.

Biological Evolution↗

PubMed1997

Dextrous hands: human, prosthetic, and robotic.

The sensory and motor capacities of the human hand are reviewed in the context of providing a set of performance characteristics against which prosthetic and dextrous robot hands can be evaluated. The sensors involved in processing tactile, thermal, and proprioceptive (force and movement) information are described, together with details on their spatial densities, sensitivity, and resolution. The wealth of data on the human hand's sensory capacities is not matched by an equivalent database on motor performance. Attempts at quantifying manual dexterity have met with formidable technological difficulties due to the conditions under which many highly trained manual skills are performed. Limitations in technology have affected not only the quantifying of human manual performance but also the development of prosthetic and robotic hands. Most prosthetic hands in use at present are simple grasping devices, and imparting a "natural" sense of touch to these hands remains a challenge. Several dextrous robot hands exist as research tools and even though some of these systems can outperform their human counterparts in the motor domain, they are still very limited as sensory processing systems. It is in this latter area that information from studies of human grasping and processing of object information may make the greatest contribution.

Artificial Limbs↗

PubMed2004

Robot-assisted neurosurgery.

Technological advances in the modern operating room have pushed neurosurgeons to the limits of their dexterity and stamina. Motion scalers and tremor filters on robots permit unprecedented precision of tool manipulation, upgrading the human hand, and closing the deftness deficit. The evolution of neurosurgical robots from stereotactic systems to hybrid systems capable of both stereotaxy and microsurgery is examined. The future of robot-assisted neurosurgery, including expanded tool sets and the prospect of semi-autonomous surgery, is discussed.

Humans↗

PubMed2004

Robot-assisted remote telepresence surgery.

A potential application of robotic surgical systems is to act as the hands and eyes of a surgeon operating from a considerable distance, enabling the surgeon to offer a variety of surgical services through gaining true telepresence by the interface of the telecommunication link and a surgical robotic system. The limited use of robot-assisted remote telepresence surgery to date has demonstrated not only that this is technologically feasible and safe but also that the patients are willing to accept its limitations when it is used in an environment where significant value from its use is realized. This chapter will discuss some of the lessons learned, the potential future applications, and the necessary next steps for its safe and widespread adoption.

Humans↗

PubMed2004

The role of the first assistant in robotic assisted surgery.

In part one of this series (BJPN 14 (1) 36-39) the introduction of the da Vinci robotic system was described (Intuitive Surgical, Inc, Mountain View, CA). This second and final part in the series describes the unique role of the first assistant in robotic assisted surgery. In September 2000, the da Vinci robotic system, the first of its kind to be installed in the UK, was introduced to St Mary's Hospital, London.

Humans↗

PubMed2003

Pericardial patch closure of an atrial septal defect using endoscopic robotic technology.

Significant progress has been made over the last several years in the area of minimally invasive cardiac surgery with beneficial clinical results and increased patient satisfaction. With the addition of robotic technology to the cardiac operating room come improvements in technical manual dexterity and decreased surgical trauma. This paper reports an endoscopic pericardial patch closure of an ostium secundum atrial septal defect (ASD) using a combination of the daVinci Surgical System (Intuitive Surgical, Sunnyvale, CA, USA) and the PORT ACCESS System (CardioVations, Sommerville, NJ, USA) for full cardiopulmonary bypass (CPB). CPB, aortic occlusion, and cardioplegia delivery were accomplished via peripheral cannulation with the PORT ACCESS System. Two robotic arms, one endoscopic camera, and one working incision were placed through ports in the thorax. The ASD was closed with a gluteraldehyde fixed pericardial patch using both running and interrupted suture. CPB and aortic occlusion times were 160 and 93 min, respectively. The patient was discharged on the second postoperative day and returned to normal lifestyle shortly thereafter. The benefits of peripheral access CPB and robotic technology to patients who do not want a median sternotomy provide an alternative method to traditional surgical intervention.

Adult↗

PubMed2004

Surgical robotics: a review and neurosurgical prototype development.

PURPOSE: The purpose of this article is to update the neurosurgical community on the expanding field of surgical robotics and to present the design of a novel neurosurgical prototype. It is intended to mimic standard technique and deploy conventional microsurgical tools. The intention is to ease its integration into the "nervous system" of both the traditional operating room and surgeon. CONCEPT: To permit benefit from updated intraoperative imaging, magnetic resonance imaging-compatible materials were incorporated into the design. Advanced haptics, optics, and auditory communication with the surgical site recreate the sight, sound, and feel of neurosurgery. RATIONALE: Magnification and advanced imaging have pushed surgeons to the limit of their dexterity and stamina. Robots, in contrast, are indefatigable and have superior spatial resolution and geometric accuracy. The use of tremor filters and motion scalers permits procedures requiring superior dexterity. DISCUSSION: Breadboard testing of the prototype components has shown spatial resolution of 30 microm, greatly exceeding our expectations. Neurosurgeons will not only be able to perform current procedures with a higher margin of safety but also must speculate on techniques that have hitherto not even been contemplated. This includes coupling the robot to intelligent tools that interrogate tissue before its manipulation and the potential of molecular imaging to transform neurosurgical research into surgical exploration of the cell, not the organ.

Artificial Intelligence↗