Gain tuning for high speed vibration control of a multilink flexible manipulator using artificial neural networkPublished: 20 March 2019 by ASME International in Journal of Vibration and Acoustics
Flexible manipulators are associated with merits like low power consumption, use of small actuators, high speed and their low cost due to fewer materials requirements than their rigid counterparts. However, they suffer from link vibration which hinders the aforementioned merits from being realized. The limitations of link vibrations are time wastage, poor precision and the possibility of failure due to vibration fatigue. This paper extends the vibration control mathematical foundation from a single link manipulator to a 3D, two links flexible manipulator. The vibration control theory developed earlier feeds back a fraction of the link root strain to increase the system damping, thereby reducing the strain. This extension is supported by experimental results. Further improvements are proposed by tuning the right proportion of root strain to feed back, and the timing using artificial neural networks. The algorithm was implemented online in Matlab interfaced with dSPACE for practical experiments. From the practical experiment, done in consideration of a variable load, Neural network tuned gains exhibited a better performance over those obtained using fixed feedback gains in terms of damping of both torsional and bending vibrations and tracking of joint angles.
Conventional actuators such as geared servos suffer drawbacks in utilizing them in robots which work closely with humans. Dielectric elastomer actuators (DEAs) overcome these challenges since they can realize natural motion patterns which are inspired by those of human muscle. To date, fabrication of such bio-mimetic soft actuators is hindered by limited electrical conductivity of the electrode materials. We aimed at developing highly conductive multi-wall carbon nanotube/polydimethylsiloxane (MWCNT/PDMS) composites for use in DEA electrodes and to develop a simple single layer actuator fabricated with these improved composites. To this end, we proposed a method to increase the dispersion of MWCNTs in PDMS and to increase the electric conductivity of the composite. Our results showed that simple crushing of the composites in addition to the use of naphthalene/toluene improved the dispersion of MWCNTs in PDMS and enhanced the DC electric conductivity of the composite. We also proposed a simple conceptual design and developed a single layer DEA based on these improved composites.
This research proposes two virtual keyboard designs and two control methods of virtual keyboards. The Keyboard I layout is a $4\times 10$ matrix with QWERTY array keypad and the Keyboard II layout is a $7\times 6$ matrix with alphabet array keypad. Both methods use thumb and index finger only to operate the keyboards. These two fingers can execute five commands: right searching, down searching, selecting character, clearing monitor, and activating the buzzer. The directions of fingers are detected by a Leap Motion sensor. The Algorithm I has two-finger gestures and 4 variables of time. The first gesture is the pointing down index finger with three functions which depends on the time variable: right searching, down searching and clearing monitor. The thumb finger pointing to the inside palm is the second gesture for selecting and activating the buzzer. The algorithm II has one additional gesture, but it has only 3 variables of time. The extra gesture is a slightly left movement of the index finger. This movement is for the down searching. The time variable is only used to clear the monitor and activate the buzzer in the 2 nd algorithm. The results showed that algorithm II can reduce the time consumed to type a single character in both keyboard types. The Algorithm I spent approximately 6.7 seconds/character. This number was reduced by Algorithm II into only 5 seconds/character. The Algorithm I had a less finger gesture, but too much time variables confused the user in operating the system. Both algorithms and virtual keyboard designs had successfully been implemented in this research. Those who can just use at least the index finger and thumb would enable them to chat with others by using this application.
Autonomous oscillatory shape change of DEA induced by the charge–discharge process under a constant voltagePublished: 01 February 2017 by World Scientific Pub Co Pte Lt in Journal of Advanced Dielectrics
Despite the promising characteristics of Dielectric Elastomel Actuator (DEA) as a practical soft actuator, the need of high voltage for its operation prevents the successful fabrication of a practical DEA, that is, the high voltage generation takes a bulky and costly power supply. Induction of complex shape change motion of DEA such as oscillatory shape change takes even a more bulky and costly multipurpose power supply. It is a serious practical issue to be overcome. In our latest study, however, we could build a simple DEA system which exhibited a relatively complex and autonomous oscillatory shape change merely under a constant voltage, though the voltage needed was high. This successful outcome must broaden the potential usefulness of DEA as a practical soft actuator.
Pattern Recognition of Overhead Forehand and Backhand in Badminton Based on the Sign of Local Euler AnglePublished: 01 June 2016 by Institute of Advanced Engineering and Science in Indonesian Journal of Electrical Engineering and Computer Science
Studying the badminton skill based on the arm movement is a challenge since the limitation of the sensor such as camera to record the movement parameter. This study proposed a new method to determine the pattern of arm movement for forehand and backhand strokes in badminton based on the sign of the local Euler angle gradient from four points of right arm segments. Each segments was identified by motion sensor attached to the dorsal surface of the hand (sensor 1), wrist (sensor 2), elbow (sensor 3) and shoulder (sensor 4). Three certified coaches participated in this research to determine the arm movement patterns for forehand and backhand strokes. Skills in forehand and backhand strokes from eight professional players and eight amateur players were observed to determint the pattern. The resulst showed that the local Euler angle can be used to recognize the arm movement pattern. Based on the observed patterns, the professional players had a higher similarity to the coaches’ patterns than those amateur players to the coaches’.
This paper investigates that the motor learning has an influence on the human perception, focusing on an upright balance. In order to apply some disturbances, we have constructed a special stool which moves horizontally as well as rotates around the roll direction. This stool allows us to provide two different conditions for the motor learning phase in whether an active trunk movements for balance maintenance is required or not. The comparison of the balance perception tests before and after the motor learning phase indicates that balance perception, i.e., the subjective upright posture, has changed if the subjects have repeated trunk movements during the motor learning phase.
Energy Transitions for the Rural Community in Kenya's Central Highlands: Small Scale Solar Powered SystemsPublished: 01 November 2015 by Elsevier BV in Energy Procedia
This paper explores Kenya's central highlands rural community's sources of energy choices’ in the last three decades. The paper tracks the changes in sources of energy (firewood, charcoal, kerosene, car battery and dry cells) up to the option of using the solar homes systems. In Kenya, the demand for clean energy for both industrial and domestic activities is on the rise. Currently, the energy for the industries and urban areas is derived largely from petroleum and hydroelectric power. On the other hand, for the low-income earning rural community in the Kenya's central highlands, firewood is however the major source of energy for most domestic activities. Considering that arid and semi-arid regions constitute over 80% of the country, the demand for firewood for instance impacts the natural ecosystems and disrupts the natural nutrient cycling.
Badminton is the most favourite sport in Indonesia. Since elementary school or earlier, children play badminton in a formal class or informal games. So, there are so many kind of styles in playing badminton. In this research, the pattern of arm kinesiology while playing badminton was studied, especially smash and backhand. The right arm of human was segmented into four parts: shoulder, elbow, wrist and back of hand. The 3-dimension local Euler angle of each parts was recorded by using gyro sensor made by Motion Node. The pattern of the segment position was investigated to distinguish smash and backhand. The result shows that there was a clear pattern caused by the movement of four parts of arm while performing smash and backhand. This pattern can be used to evaluate a process of arm moving while performing smash or backhand in badminton.
The Study of Dynamic Characteristics of Selemion CMV-based IPMC Actuators in Humidity-Controlled EnvironmentsPublished: 01 January 2015 by Japan Society of Applied Electromagnetics and Mechanics in Journal of the Japan Society of Applied Electromagnetics and Mechanics
Rotation Matrix to Operate a Robot Manipulator for 2D Analog Tracking Objects Using ElectrooculographyPublished: 23 July 2014 by MDPI in Robotics
Performing some special tasks using electrooculography (EOG) in daily activities is being developed in various areas. In this paper, simple rotation matrixes were introduced to help the operator move a 2-DoF planar robot manipulator. The EOG sensor, NF 5201, has two output channels (Ch1 and Ch2), as well as one ground channel and one reference channel. The robot movement was the indicator that this system could follow gaze motion based on EOG. Operators gazed into five training target points each in the horizontal and vertical line as the preliminary experiments, which were based on directions, distances and the areas of gaze motions. This was done to get the relationships between EOG and gaze motion distance for four directions, which were up, down, right and left. The maximum angle for the horizontal was 46°, while it was 38° for the vertical. Rotation matrixes for the horizontal and vertical signals were combined, so as to diagonally track objects. To verify, the errors between actual and desired target positions were calculated using the Euclidian distance. This test section had 20 random target points. The result indicated that this system could track an object with average angle errors of 3.31° in the x-axis and 3.58° in the y-axis.
Affine Transform to Reform Pixel Coordinates of EOG Signals for Controlling Robot Manipulators Using Gaze MotionsPublished: 10 June 2014 by MDPI in Sensors
Biosignals will play an important role in building communication between machines and humans. One of the types of biosignals that is widely used in neuroscience are electrooculography (EOG) signals. An EOG has a linear relationship with eye movement displacement. Experiments were performed to construct a gaze motion tracking method indicated by robot manipulator movements. Three operators looked at 24 target points displayed on a monitor that was 40 cm in front of them. Two channels (Ch1 and Ch2) produced EOG signals for every single eye movement. These signals were converted to pixel units by using the linear relationship between EOG signals and gaze motion distances. The conversion outcomes were actual pixel locations. An affine transform method is proposed to determine the shift of actual pixels to target pixels. This method consisted of sequences of five geometry processes, which are translation-1, rotation, translation-2, shear and dilatation. The accuracy was approximately 0.86° ± 0.67° in the horizontal direction and 0.54° ± 0.34° in the vertical. This system successfully tracked the gaze motions not only in direction, but also in distance. Using this system, three operators could operate a robot manipulator to point at some targets. This result shows that the method is reliable in building communication between humans and machines using EOGs.
IPMC bending predicted by the circuit and viscoelastic models considering individual influence of Faradaic and non-Farad...Published: 01 January 2014 by Elsevier BV in Sensors and Actuators B: Chemical
Consideration of the disturbance suppression of LQI2-degree-of-freedom control system of a Piezoelectric ActuatorPublished: 01 January 2014 by Japan Society of Applied Electromagnetics and Mechanics in Journal of the Japan Society of Applied Electromagnetics and Mechanics
Self-Sensing Control of Nafion-Based Ionic Polymer-Metal Composite (IPMC) Actuator in the Extremely Low Humidity Environ...Published: 01 October 2013 by MDPI in Actuators
This paper presents feedforward, feedback and two-degree-of-freedom control applied to an Ionic Polymer-Metal Composite (IPMC) actuator. It presents a high potential for development of miniature robots and biomedical devices and artificial muscles. We have reported in the last few years that dehydration treatment improves the electrical controllability of bending in Selemion CMV-based IPMCs. We tried to replicate this controllability in Nafion-based IPMC. We found that the displacement of a Nafion-based IPMC was proportional to the total charge imposed, just as in the Selemion-CMV case. This property is the basis of self-sensing controllers for Nafion-based IPMC bending behavior: we perform bending curvature experiments on Nafion-based IPMCs, obtaining the actuator's dynamics and transfer function. From these, we implemented self-sensing controllers using feedforward, feedback and two-degree-of-freedom techniques. All three controllers performed very well with the Nafion-based IPMC actuator.
Motor learning in the context of arm reaching movements has been frequently investigated using the paradigm of force-field learning. It has been recently shown that changes to somatosensory perception are likewise associated with motor learning. Changes in perceptual function may be the reason that when the perturbation is removed following motor learning, the hand trajectory does not return to a straight line path even after several dozen trials. To explain the computational mechanisms that produce these characteristics, we propose a motor control and learning scheme using a simplified two-link system in the horizontal plane: We represent learning as the adjustment of desired joint-angular trajectories so as to achieve the reference trajectory of the hand. The convergence of the actual hand movement to the reference trajectory is proved by using a Lyapunov-like lemma, and the result is confirmed using computer simulations. The model assumes that changes in the desired hand trajectory influence the perception of hand position and this in turn affects movement control. Our computer simulations support the idea that perceptual change may come as a result of adjustments to movement planning with motor learning.
Experimental Considerations on Signal Feature and Kernel/Prameters of SVM in Hand Motion Classification from sEMGPublished: 01 January 2013 by Japan Society of Mechanical Engineers in TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C
Introduction and Evaluation of the Efficacy of Community-based On-site Learning of Pharmacist ServicesPublished: 01 January 2013 by Japanese Society of Pharmaceutical Health Care and Sciences in Iryo Yakugaku (Japanese Journal of Pharmaceutical Health Care and Sciences)
Hokkaido Pharmaceutical University School of Pharmacy provides students with on-site learning of pharmacist services (OSL, hereafter) in which they learn about the roles of local medical institutions, and collaboration between such institutions and pharmacists. Our aim is to train students to become highly qualified pharmacists as desired by the community.We provided our 3rd-year students with OSL at seven local medical institutions in Yubari City. A collaboration agreement was established between Yubari Medical Center, one of the institutions, and our College. The aims of the OSL were to teach students about the roles of pharmacists in the community and to give them a better understanding of the different types of pharmacist jobs. The students were surveyed by questionnaire before and after the OSL to examine changes in their understanding as well as the extent of their knowledge.Almost all degrees of their understanding as well as recognition of the necessity for the content of the OSL were significantly improved after OSL as compared to before OSL. Although they had already understood the tasks of physicians, nurses and pharmacists very well, the OSL seems to have raised their awareness of pharmacists' services as a whole in the local community especially by offering OSL in local medical institutions, nursing homes for the elderly and welfare facilities. We think that educating pharmacy students about community-based team medical care can be helpful for training them to become pharmacists who are capable of providing appropriate services in collaboration with society.
Quadrupeds show several locomotion patterns when adapting to environmental conditions. An immediate transition among walk, trot, and gallop implies the existence of a memory for locomotion patterns. In this article, we postulate that motion pattern learning necessitates the repetitive presentation of the same environmental conditions and aim at constructing a mathematical model for new pattern learning. The model construction considers a decerebrate cat experiment in which only the left forelimb is driven at higher speed by a belt on a treadmill. A central pattern generator (CPG) model that qualitatively describes this decerebrate cat's behavior has already been proposed. In developing this model, we introduce a memory mechanism to store the locomotion pattern, where the memory is represented as the minimal point of the potential function. The recollection process is described as a gradient system of this potential function, while in the memorization process a new pattern learning is regarded as a new minimal point generation by the bifurcation from an already existing minimal point. Finally, we discuss the generalization of this model to motion adaptation and learning.
A self-tuning vibration control of a rotational flexible arm using neural networks is presented. To the self-tuning control system, the control scheme consists of gain tuning neural networks and a variable-gain feedback controller. The neural networks are trained so as to make the root moment zero. In the process, the neural networks learn the optimal gain of the feedback controller. The feedback controller is designed based on Lyapunov's direct method. The feedback control of the vibration of the flexible system is derived by considering the time rate of change of the total energy of the system. This approach has the advantage over the conventional methods in the respect that it allows one to deal directly with the system's partial differential equations without resorting to approximations. Numerical and experimental results for the vibration control of a rotational flexible arm are discussed. It verifies that the proposed control system is effective at controlling flexible dynamical systems.
This paper presents the self-sensing control of a microactuator for hard disk drives. The microactuator uses a PZT actuator pair installed on the suspension assembly. The self-sensing microactuator forms a combined sensing and actuation mechanism. Direct velocity feedback and positive position feedback are used in this paper. Our experimental results show that both strategies are effective in suppressing vibrational modes and successfully demonstrate the feasibility of using a self-sensing actuator on an HDD suspension assembly.
Highly dehydrated gold foil-coated Selemion AMV exhibited large bending under electrical stimulation. It bore a relatively well-controllable bending characteristic by the control of electrical stimulation. Conventional ionic polymer–metal composite bending mechanisms could not explain its bending behavior. We speculated that Joule heat played a central role in the bending induction. Employing the classical lamination theory, the influence of Joule heat on its bending behavior was theoretically investigated. The results calculated roughly agreed with the experimental results. Hence, we concluded that the Joule heat was the primary cause of bending induction.
This paper describes a development of an autonomous two-wheeled vehicle robot. The model of the two-wheeled vehicle using steering control is derived. The control systems are designed by linear quadratic regulator and linear quadratic integral method. Stabilization is achieved by measuring roll angle and roll rate and controlling the steering torque. The experimental results and simulation results show stable running control of the two-wheeled vehicle robot and coincident with each other. The approach is validated through these results.
This paper presents the development of a small experimental rocket for the National Launching Campaign held by the DGAEM in France since 2009. The campaign organized by CNES was conducted by the French Association of Planete Sciences. The rocket design was developed by Space Club Gifu and Sasaki Lab at Gifu University. The main mission is the autonomous navigation of a quasi-satellite maneuvering with a parachute and two propellers to a target point using GPS data. The rocket is 2m long, 150mm in diameter, weight 11.4kg and made entirely of CFRP. With a solid rocket motor provided by CNES, the rocket can reach an altitude of 840m. Onboard are a pressure sensor, accelerometer, GPS and two video cameras. The video cameras begin monitoring at launch. The acceleration, velocity and position were recorded for later comparison to simulation data. While the rocket launch and quasi-satellite deployment were successful, strong winds prevented the latter from maneuvering to the target point. All components were recovered intact and all recorded data were available for analysis.
A diagram of the minimum necessary internal force required to resist external forces on two-point-grasped objects in two...Published: 01 November 2011 by Cambridge University Press (CUP) in Robotica
A bimorph actuator of PVC-CFRP laminate (PVC: polyvinylchloride; CFRP: carbon fiber reinforced plastic) is fabricated, where its bending results from the large disparity between the coefficients of thermal expansion of PVC and CFRP. Thermal expansion is brought about by applying a voltage to the CFRP layer of the PVC-CFRP laminate to generate Joule heat. Thus, the PVC-CFRP laminate acts as an electroactive polymer actuator. The authors experimentally confirmed that laminate temperature due to Joule heat completely determines laminate deflection curvature, and also demonstrated that temperature determines the blocking force generated by PVC-CFRP laminate.
Bending control of Nafion-based electroactive polymer actuator coated with multi-walled carbon nanotubesPublished: 01 August 2011 by Elsevier BV in Sensors and Actuators B: Chemical
Electrical bending control of Nafion-based ionic polymerâmetal composite (IPMC) is quite difficult. Unlike a conventional fully hydrated noble metal-coated Nafion type IPMC, however, highly dehydrated silver-coated Nafion type IPMC exhibited better electrical bending controllability. Embedding of the multi-walled carbon nanotube (MWCNT) into Nafion surface promoted adsorption of a larger quantity of silver on the Nafion surface, since the MWCNT surface served as adsorption sites for silver. A MWCNT-embedded Nafion coated with such a large quantity of silver (SCNT-Naf) exhibited large bending curvature under an applied voltage when in a highly dehydrated state, because of large scale induction of silver redox reaction. We could even achieve autonomous bending curvature control of the highly dehydrated SCNT-Naf quantitatively by automatically monitoring total charge imposed on it.
Passivity based control for a magnetically levitated flexible beam with rate estimation via the extended Kalman filterin...Published: 31 May 2011 by IOS Press in International Journal of Applied Electromagnetics and Mechanics
Active random noise control using adaptive learning rate neural networks with an immune feedback lawPublished: 31 May 2011 by IOS Press in International Journal of Applied Electromagnetics and Mechanics
Neural network based control of a suspension assembly with self-sensing micro-actuator for dual-stage HDDPublished: 31 May 2011 by IOS Press in International Journal of Applied Electromagnetics and Mechanics
Motion Control of Biped Lateral Stepping Based on Zero Moment Point Feedback for Adaptation to SlopesPublished: 04 February 2011 by IntechOpen in Biped Robots
This paper presents identification and control of a 10-m antenna via accelerometers and angle encoder data. Artificial neural networks can be used effectively for the identification and control of nonlinear dynamical system such as a large flexible antenna with a friction drive system. Some identification results are shown and compared with the results of conventional prediction error method. And we use a neural network inverse model to control the large flexible antenna. In the neural network inverse model, a neural network is trained, using supervised learning, to develop an inverse model of the antenna. The network input is the process output, and the network output is the corresponding process input. The control results show the validation of the ANN approach for identification and control of the 10-m flexible antenna.
Mathematical models predicting the behaviour of IMPCs (Ionic Polymer-Metal Composites ) were built and their validity was verified computationally as well as experimentally. A transfer function associating the applied input voltage with the IPMC tip displacement was derived based on results obtained by vibration analysis. Employing the derived transfer function, three mathematical models, based on feed forward, feedback and two-degree-of-freedom models, were formulated. Computational and experimental verification of these models revealed that the feedback and two-degree-of-freedom models were capable of high performance in controlling the bending of an IPMC.
This paper addresses a biped balancing task in which an unknown external force is exerted, using the so-called ‘ankle strategy’ model. When an external force is periodic, a human adaptively maintains the balance, next learns how much force should be produced at the ankle joint from its repeatability, and finally memorized it as a motion pattern. To acquire motion patterns with balancing, we propose a control and learning method: as the control method, we adopt ground reaction force feedback to cope with an uncertain external force, while, as the learning method, we introduce a motion pattern generator that memorizes the torque pattern of the ankle joint by use of Fourier series expansion. In this learning process, the period estimation of the external force is crucial; this estimation is achieved based on local autocorrelation of joint trajectories. Computer simulations and robot experiments show effective control and learning results with respect to unknown periodic external forces.
A circularly coupled oscillator system for relative phase regulation and its application to timing control of a multicyl...Published: 01 October 2010 by Elsevier BV in Communications in Nonlinear Science and Numerical Simulation