For a robotic system, the complete description of the end-effector motion requires six independent parameters, while the desired end-effector motion for a task often needs less than 6 d.o.f. Therefore, the end-effector motion can be divided into desired motion and undesired motion. The end-effector motion is transformed from the joint motions. In this paper, the efficiency of the joint motions to implement the desired motion is investigated and a new concept called motion purity is proposed to measure this efficiency. The new concept is more comprehensive and direct than other existing performance measures, such as the volume of workspace and manipulability. It is appropriate as a design objective at various phases in designing a robotic mechanism. The tripod machine tool is studied and its structure is optimized from the viewpoint of the motion purity.

Категория: Ищем научные статьи | Нет комментариев »

This paper presents the power assistance system of working habiliment type for painting worker in ship-building. The painting worker carrying several tools such as spray gun, brush and roller should be stayed to do painting job in closed working space or inside internal wall of ship large block and in long time. Specially, the power habiliment system is realized by developing the mechanism and control technology to reduce the working load to be transferred to the muscular system of worker. And also it is developed to realize the human friendly optimal working motion. This paper shows the design of multi-axis link mechanism to do painting job of a variety of motion. It shows the control technology of painting work system to reduce the effect of the weight of painting tool and wearable painting system and the working load of painting process such as the reaction force of spray gun.

Категория: Ищем научные статьи | Нет комментариев »

Experiments for the online closed-loop control of neural prosthetics require feedback within 100ms. In a typical neurophysiology laboratory with local computing machines, a majority of this time is spent on acquiring and analyzing the neural signals and a minority (i.e. less than a millisecond) is actual data transfer among machines on local- or campus-area networks. However, the local computing machines may not offer the computational resources necessary for running complex algorithms or scenarios that have been recently proposed. While scientists can take advantage of remote computing resource providers, wide-area networks present much larger latencies that can affect an online experiment. This work presents a split modeling approach that allows the execution of a controller on the neurophysiology resource and the execution of computationally intensive modeling and adaptation algorithms on a remote datacenter, even with the inevitable network latency. Simulation results are presented to quantify how the accuracy of the controller is affected by the split modeling approach in the presence of delays, and to demonstrate that scientists can take advantage of remotely available massive resources.

Категория: Ищем научные статьи | Нет комментариев »

Purpose.  To investigate the effects of dynamic ankle-foot orthoses (DAFOs) on functional ambulation activities, weight bearing and spatio-temporal characteristics of hemiparetic gait and to inquire whether wearing a DAFO for 3 months has a carryover effect.

Method. Fourteen chronic hemiparetic patients who could walk independently with or without a cane were the subjects of the study. Patients were assessed initially with tennis shoes and were given custom fabricated DAFOs which they wore for three months and were retested under two conditions: with tennis shoes only and with DAFOs worn in these shoes. All patients were assessed for weight bearing percentage of the affected side, cadence, step length of the involved and uninvolved sides, step width, functional reach, timed up and go, timed down stairs, timed up stairs, physiologic cost index and velocity.

Results. Comparison of initial and third month assessments with shoes only condition showed that there was no significant improvement for the measured parameters. When comparison was made at the third month while patients were wearing tennis shoes only and when they were wearing DAFO’s in their shoes there was a significant difference in favour of the condition where patients were wearing DAFOs.

Conclusion. The benefits of using DAFOs in chronic hemiparetic patients are lost when the patients are not wearing their orthoses.

Категория: Ищем научные статьи | Нет комментариев »

Patients with neurological disorders, such as stroke survivors, can be treated with physical rehabilitation to regain motor control and function. Conventional therapy techniques are labor intensive and non-standardized. This is especially true in gait rehabilitation. A natural and tunable rehabilitation gait system (NaTUre_gaits) has been developed to assist gait rehabilitation with body-weight support locomotion training (BWSLT), gait control (GC), balance control (BC) and pelvic control (PC). All of those components are attached to a mobile platform (MP) with a total weight of more than 200kg. In order to coordinate the system with the motion of GC/BC/PC and to provide BWS for the subject throughout the walking test, the mobile system needs to move adaptively and steadily against those dynamic disturbance and heavy load. Motivated by reducing the tuning time, an identification and control method are proposed. Based on the relay response during operation, the system model is obtained and then PD controller with feed forward feedback is designed. Trials with/without subject are performed to demonstrate the effectiveness and merit of the proposed modeling and tuning method.

Категория: Ищем научные статьи | 1 Комментарий »