Sanghun Pyo

Smartphone Based Control Architecture of Teaching Pendant for Industrial Manipulators

Industrial manipulators performs various tasks in an environment where operator has to monitor closely and also interact upon a detailed level with the robot. The operation of the robot from a remote area is possible through some wireless communication, but a two way communication for feedback is most desirable. The proposed smart phone based teaching pendant provides a user friendly interactive control input method to the robots operator. The operator can not only give commands to the end effector, but during the continuous mode operation, the operator can pause, repeat and restart the subtasks of whole operation remotely. The two way network socket communication running on threads also gives a real time feedback data for detailed monitoring. OpenGL based smartphone visual drawing also gives a more understandable monitoring method of current robot status.

Development of an active haptic cane for gait rehabilitation

This research aims to develop a novel gait assistive device with enhanced gait stability and training efficiency for stroke patients. The proposed assistive device for mobility aid is composed of a motored wheel and a cane for providing only a light grip force, which prevent a patient using excessive support force of an upper limb like a conventional cane and motivate the patient to use more actively a paralyzed limb due to the reduced weight support. In addition, the proposed device can provide the user with intuitive and safe interaction during walking by integrating an F/T sensor and a tilt sensor at the cane, and a switch sensor at the hand grip. Also, admittance control has been implemented for a patient, it intuitively changes cane speed by measuring interaction forces at the hand grip. A hemi-paretic stroke patient participated in the walking experiments as a pilot study to verify effectiveness of the proposed system. The results showed that the patient could improve walking speed and muscle activation during experiments with a constant speed mode of the haptic cane. Moreover, in the admittance control mode of the haptic cane, the patient could keep higher preferred walking speed and higher gait stability regardless of magnitude of resistance forces. The proposed gait assistive device with cheap, compact and easy-to-use characteristics can provide efficient gait training modes to chronic stroke patients.

Haptic based gait rehabilitation system for stroke patients

Among most existing gait rehabilitation robots, it is difficult to find adequate devices for gait rehabilitation of chronic stroke patients who can already stand and move but still need to rehabilitate the affected lower limb through simple, compact, and easy-to use devices. This paper presents a novel haptic based gait rehabilitation system (HGRS) which has the potential to provide over-ground gait training regimens for post-stroke ambulatory subjects. It consists of a portable cane for kinesthetic sensing and a wearable vibrotactor array for tactile biofeedback. Contact of user with the handle provides light grip force, it serves the purpose of balance assurance and increased muscle activity through light touch concept and vibrotactors contribute in enhancing the gait modification through afferent signal of vibration. Walking trials conducted with stroke patients indicate increased muscle activation and balance, and improved temporal symmetry with use of HGRS. HGRS is capable of assisting physical therapists in training individuals with stroke suffering from gait abnormalities. In addition, it is easy to use and low-cost which makes it reachable to a vast domain of subjects suffering from gait abnormalities.

A novel robotic knee device with stance control and its kinematic weight optimization for rehabilitation

It is important to develop a robotic orthosis or exoskeleton that can provide back-drivable and good assistive performances with lightweight structures for overground gait rehabilitation of stroke patients. In this paper, we describe a robotic knee device with a five-bar linkage to allow low-impedance voluntary knee motion within a specified rotation range during the swing phase, and to assist knee extension during the stance phase. The device can provide free motion through the five-bar linkage with 2-degree-of-freedom (DOF) actuation via the patients shank using a linear actuator, and can assist knee extension at any controlled knee angle while bearing weight via a geared five-bar linkage with 1 DOF actuation of the linear actuator. The kinematic transition between the two modes can be implemented by contact with a circular structure and a linear link, and the resultant range of motion can be determined by the linear actuator. The kinematic weight of the device was optimized using the simple genetic algorithm to reduce the mass. The optimization cost function was based on the sum of the total link lengths and the actuator power. The optimization results reduced the total link length and motor power by 47% and 43%, respectively, compared to the initial design. We expect that the device will facilitate rehabilitation of stroke patients by allowing safe and free overground walking while providing support for stumbling.

A Novel Kinematic Design of a Knee Orthosis to Allow Independent Actuations During Swing and Stance Phases

Nowadays many neurological diseases such as stroke and Parkinson diseases are continually increasing. Orthotic devices as well as exoskeletons have been widely developed for supporting movement assistance and therapy of patients. Robotic knee orthosis can compensate stiff-knee gait of the paralyzed limb and can provide patients consistent assistance at wearable environments. With keeping a robotic orthosis wearable, however, it is not easy to develop a compact and safe actuator with fast rotation and high torque for consistent supports of patients during walking. In this paper, we propose a novel kinematic model for a robotic knee orthosis to drive a knee joint with independent actuation during swing and stance phases, which can allow an actuator with fast rotation to control swing motions and an actuator with high torque to control stance motions, respectively. The suggested kinematic model is composed of a hamstring device with a slide-crank mechanism, a quadriceps device with five-bar/six-bar links, and a patella device for knee covering. The quadriceps device operates in five-bar links with 2-dof motions during swing phase and is changed to six-bar links during stance phase by the contact motion to the patella device. The hamstring device operates in a slider-crank mechanism for entire gait cycle. The kinematics and velocity/force relations are analyzed for the quadriceps and hamstring devices. Finally, the adequate actuators for the suggested kinematic model are designed based on normal gait requirements. The suggested kinematic model will allow a robotic knee orthosis to use compact and light actuators with full support during walking.

Design of 6-DOF Manipulator Intuitive Teaching System Using Smart Phone Orientation: User Friendly and Intuitive Teaching Operation for 6-DOF Manipulator

Conventional teaching pendent is widely utilized to define the task manipulation of industrial robot. But for efficient teaching task, we need to make the novel intuition teaching method and user friendly interface to realize end effectors position and orientation easier. In addition to enhance time efficiency of teaching task, tele-operation function and mobility are also needed. In this regard, this research proposes smart phone based intuitive teaching pendant. The way of basic idea is that the smart phone orientation information can be considered as some control device which has universal joint in base part, and we match orientation information of smart phone to end effector of manipulator. Furthermore, a user study is performed to compare the proposed smart teaching pendant with conventional approach in a given scenario. And we can show that suggested method has more time efficiency comparing with the traditional teaching works in the virtual environment applied the idea of teaching method we designed.

A Novel Gait Assistance System Based on an Active Knee Orthosis and a Haptic Cane for Overground Walking

The use of an active knee orthosis can cause postural instability in hemiparetic users due to its weight and the uncompensated dynamics of the paralyzed limb. Here, we have proposed a gait assistance system that combines a haptic cane and an active knee orthosis for post-stroke over-ground gait training. The haptic cane is composed of a tilted conventional cane mounted on a motorized wheel, and the active knee orthosis device is based on a novel kinematic design. The proposed system can provide postural stability through proprioceptive augmentation, while providing support to the affected lower limb. To identify the effects and potential implications of the proposed gait assistance system, a pilot study was performed with one young healthy subject wearing an ankle weight (4 kg) on one leg. Improvements were observed in mediolateral and anteroposterior trunk sway. The proposed gait assistance system exhibited promising outcomes in this pilot study. The translation of this enhanced gait stability to hemiparetic stroke suffering individuals is warranted.

Development of an Active Gait Assistive Device with Haptic Information

The purpose of this research is to develop a gait assistive device to enhance the gait stability and training efficiency of stroke patients. The configuration of this device is mainly composed of a motored wheel and a single cane whose lower end is attached to a motored wheel frame. A patient can feel haptic information from continuous ground contact from the wheel while walking through the grip handle. In addition, the wheeled cane can avoid using excessive use of the patient`s upper limb for weight support and motivate the patient to use a paralyzed lower limb more actively. Moreover, the proposed device can provide intuitive and safe user interaction by integrating a force sensor and a tilt sensor equipped to the cane frame, and a switch sensor at the cane`s handle. The admittance control has been implemented for the patient to change the walking speed intuitively by using the interaction forces at the handle. A hemi-paretic stroke patient participated in the walking assistive experiments as a pilot study to verify the effectiveness of the proposed haptic cane system. The results showed that the patient could improve walking speed and muscle activations during walking with a constant speed mode of the haptic cane. Moreover, the patient could maintain the preferred walking speeds and gait stability regardless of the magnitude of resistance forces with the admittance control mode of the haptic cane. The proposed robotic gait assistive device with a simple and intuitive mechanism can provide efficient gait training modes to stroke patients with high possibilities of widespread utilizations.

Optimal Kinematic Design of a Novel Robotic Knee Device for Gait Rehabilitation with Stance Control

In this paper, we have proposed a novel robotic knee device with a five-bar linkage to allow low impedance voluntary knee motions within a specified rotation range during swing phase and to assist knee extension motions during stance phase after reaching the boundary of the rotation range. The proposed device can provide free knee motions through the five-bar linkage with 2-DOF degree of freedom actuations by a patients shank and a linear actuator, and can assist knee extension at any controlled knee angle during weight bearing by a geared five-bar linkage with 1-DOF actuation of the linear actuator. The kinematic transition between two modes can be implemented by contact mechanism of a circular structure knee joint and a linear link patella, and the resultant knee rotation range can be determined by the linear actuator. A weight optimization scheme with a simple genetic algorithm SGA is performed to increase portability of the proposed device and minimize the side-effects of increased link numbers as compared to existing four-bar mechanisms. The cost function is composed of sums of normalized total link lengths and normalized motor powers. The optimization results show that the total link length and motor power were reduced to 47% and 43% respectively, as compared to initial design. The proposed robotic knee device can provide a new rehabilitation mode for a stroke patient to allow safe and self-motivated overground walking with minimum concern of falling down.

Optimal Design of a Novel Knee Orthosis using a Genetic Algorism

The objective of this paper is to optimize the design parameters of a novel mechanism for a robotic knee orthosis. The feature of the proposed knee othosis is to drive a knee joint with independent actuation during swing and stance phases, which can allow an actuator with fast rotation to control swing motions and an actuator with high torque to control stance motions, respectively. The quadriceps device operates in five-bar links with 2-DOF motions during swing phase and is changed to six-bar links during stance phase by the contact motion to the patella device. The hamstring device operates in a slider-crank mechanism for entire gait cycle. The suggested kinematic model will allow a robotic knee orthosis to use compact and light actuators with full support during walking. However, the proposed orthosis must use additional linkages than a simple four-bar mechanism. To maximize the benefit of reducing the actuators power by using the developed kinematic design, it is necessary to minimize total weight of the device, while keeping necessary actuator performances of torques and angular velocities for support. In this paper, we use a SGA (Simple Genetic Algorithm) to minimize sum of total link lengths and motor power by reducing the weight of the novel knee orthosis. To find feasible parameters, kinematic constraints of the hamstring and quadriceps mechanisms have been applied to the algorithm. The proposed optimization scheme could reduce sum of total link lengths to half of the initial value. The proposed optimization scheme can be applied to reduce total weight of general multi-linkages while keeping necessary actuator specifications.