http://ieeexplore.ieee.org TOC Alert for Publication# 3516 2009 November 19 15 1 C1 C1 38 15 1 C2 C2 38 Active control of phase-sensitive interferometric metrology systems is necessary for low noise, high resolution, high bandwidth, and parallel operation. Conventional active control methods have several drawbacks like low SNR, high complexity, and low bandwidth. With the development of micromachined scanning grating interferometers ( $mu$SGIs), high-bandwidth parallel active control of an array of interferometers is feasible. This paper introduces a novel “recurrent-calibration-based active control algorithm.” Utilizing the high-bandwidth integrated electrostatic actuator, this algorithm splits the calibration of the optics and the displacement measurement in time to achieve better noise reduction. The novel algorithm is implemented digitally using a field-programmable gate array on an array of $mu$SGIs simultaneously. Nonlinearity and the limited range of actuation of the electrostatic actuator affect the performance of the active control. It is compensated by using a lookup table and a gain reversal algorithm. A system model is built to design and analyze the control algorithm. A $mu$SGI interferometer setup validates the model and control approach. The control algorithm reduces the vibration noise by 40 dB at low frequencies with a cutoff frequency of 6.5 kHz. The resolution of the $mu$SGI coupled with the control system is measured as $hbox{1} times hbox{10}^{-4} hbox{nm}_{rm rms}/surd hbox{Hz}$ . ]]> 15 1 1 8 698 This paper is concerned with the development of the trident snake robot , a new example of nonholonomic mobile robot proposed by the authors. The robot has three-pointed shape composed of a center block and three branches, each of which has a passive nonslide wheel. It is modeled as a nonnilpotent driftless system with two generators; its control is a challenging problem, not only because it cannot be treated by continuous control law, but because it cannot be converted to any easy class of nonholonomic systems such as chained form. In this paper, we realized the one-link trident snake robot and applied a periodic control algorithm based on Lie bracket motion. Effectiveness of the proposed algorithm is examined with control experiments. ]]> 15 1 9 16 565 Operators’ intelligent and skillful decisions are necessary for the teleoperation of a mobile robot when there are many scattered obstacles. Among the sensors used for environment recognition, the camera is the most popular and powerful. However, there are several limitations in the camera-based teleoperation of a mobile robot. For example, shadowed and curved areas cannot be viewed using a narrow view-angle camera, especially in an environment with bad illumination and several obstacles. Therefore, it is necessary to have other sensory information for reliable teleoperations. In this study, 16 ultrasonic sensors are attached around a mobile robot in a ring pattern to measure the distances to the obstacles and a collision vector is introduced as a new tool for obstacle avoidance, which is defined as the normal vector from an obstacle to the mobile robot. Based on this collision vector, a virtual reflection force is generated to avoid the obstacles and then the reflection force is transferred to the operator who is holding the joystick used to control the mobile robot. Based on this reflection force, the operator can control the mobile robot more smoothly and safely. For this bidirectional teleoperation, a master joystick system using a two-axis hall sensor was designed to eliminate the nonlinear region, which exists in a general joystick with two motors and potentiometers. The effectiveness of the collision vector and force-reflection joystick is verified by comparing two vision-based teleoperation experiments, with and without force reflection. ]]> 15 1 17 26 1281 We have developed three different versions of a multifunction haptic device that can display touch, pressure, vibration, shear force, and temperature to the skin of an upper extremity amputee, especially the one who has undergone targeted nerve reinnervation (TR) surgery. In TR patients, sensation from the reinnervated skin is projected to the missing hand. This paper addresses the design of the mechanical display, the portion responsible for contact, pressure, vibration, and shear force. A variety of different overall design approaches satisfying the design specifications and the performance requirements are considered. The designs of the fully prototyped haptic devices are compared through open-loop frequency response, closed-loop force response, and tapping response in constrained motion. We emphasize the tradeoffs between key design factors, including force capability, workspace, size, bandwidth, weight, and mechanism complexity. ]]> 15 1 27 39 1037 The demands on bearingless drive configurations concerning performance as well as costs are high. The proposed bearingless brushless dc motor consists of five concentrated coils in a symmetrical arrangement, which generate radial forces and motor torque simultaneously in interaction with a permanent-magnet-excited disk-shaped rotor. Additionally, tilting deflection and the axial position of the rotor are stabilized passively by means of magnetic reluctance forces. Thus, system costs can be reduced significantly compared to a conventional bearingless motor setup, which actively stabilizes all 6 DOF. Due to the nonlinearity of the plant, the use of linear control design methods alone is not suitable for achieving a high operation performance. This paper introduces a novel radial position and motor torque control algorithm for a bearingless brushless dc motor based on the theory of feedback linearization. Thereby, the combined model of translatory and rotatory dynamics can be split into independent linear systems by means of a nonlinear change of system coordinates and a static-state feedback. Experimental results demonstrate the effectiveness of the proposed approach. ]]> 15 1 40 47 530 This paper describes the mechatronics design, prototype testing, and control of a steerable nips component for paper path mechanisms in high-speed color printers and photocopiers. When placed upstream from the image transfer station along the paper path, this device precisely controls the longitudinal, lateral, and skew directions of papers sheets, as they arrive to the image transfer station. The paper also presents a complete kinematic and dynamic analysis of the paper sheet steering mechanism, which is validated by experimental results. It is shown that the dynamics of a sheet under the control of the steerable nips mechanism are nonlinear and subject to nonholonomic constraints. A feedback linearization control strategy that includes dynamic surface control is developed and implemented to control the sheet's position and angular orientation under the condition that the sheet's speed in the longitudinal direction remains positive at all times. Experimental results verify that the steerable nips mechanism under the proposed feedback linearization control strategy is able to meet or exceed all design performance requirements for deployment as a component of an actual printer paper path control mechanism. ]]> 15 1 48 58 1402 Eddy currents induced within nonlaminated electromagnetic actuators by time-varying magnetic fields have a strong effect on the dynamics and control of electromagnetic suspension systems. This paper examines the modeling of these suspension systems and resolves two important problems: 1) the effect of time-varying flotor position on electromagnetic force production and 2) the proper manner in which to model voltage-mode operation of the suspension. The models developed are explicit functions of actuator material and geometric properties. The investigation focuses on axisymmetric cylindrical electromagnetic actuators. Similar results are provided for nonlaminated actuators with C-core stators. Experimental results are presented that demonstrate the accuracy of the modeling approach. ]]> 15 1 59 69 592 A novel smart sensing unit is developed in this paper for vibration measurement and machinery condition monitoring. The microprocessor-based smart sensor can collect 2-D vibrations and conduct signal analysis. When mounted in proximity of a bearing housing (a general case), it can conduct online fault detection in shafts and bearings. A correlation spectrum method is proposed as a digital encoder to recognize shaft rotation speed. A wavelet energy spectrum technique is adopted for bearing fault detection. A novel strategy is suggested to extract representative features and enhance feature characteristics by integrating the resulting wavelet energy functions over different frequency bands. The effectiveness of the developed smart sensor and the related fault detection techniques is verified by experimental tests corresponding to different bearing conditions. Test results show that the developed smart sensing unit is an effective measurement and condition monitoring tool; the wavelet energy spectrum technique is a robust bearing fault detection method, especially for nonstationary feature extraction and analysis. ]]> 15 1 70 78 775 A realistic prediction of the in-orbit transient performance of a nanosatellite space radiator requires a ground-based equivalent space radiator with a small size, simple configuration, and fast response. For this purpose, we present in this paper the design concept, operating principle, and analysis algorithm of a novel equivalent physical simulator (EPS) consisting of a thermoelectric cooler (TEC), a plate-fin heat sink, and a forced cooling fan. The TEC-based EPS achieves the purpose of simulating the in-orbit transient heat radiation in earth's atmospheric environment by adapting two key parameters: the TEC cooling capacity and the thermal resistance of the heat sink cooling fan. This paper offers results of in-depth numerical parametric studies leading to an EPS design that enables robust simulations under both hot-case and cold-case operations. In addition, we present the design and evaluation of a fuzzy controller for the EPS as an attractive alternative to the traditional PID controller. The fuzzy control presented here will have other potential thermal control applications where TECs and forced cooling heat sinks are employed. ]]> 15 1 79 87 677 In this paper, an electromagnetic actuator having four discrete positions is discussed. The principle, the modeling, and an experimental device of this actuator are presented in this study. This actuator is composed of a mobile permanent magnet, four fixed permanent magnets, which ensure the holding of the discrete positions, and two perpendicular wires to switch independently in two perpendicular directions. The mobile part has four discrete positions, two in each direction. An electromagnetic actuator modeling has been realized to compute the magnetic and electromagnetic forces exerted on the mobile magnet and its displacement. The experimental device was designed using this model and then manufactured. The stroke of the mobile part is 1 mm $times$ 1 mm. The driving current ranges from 3 to 7 A. A comparison between experimental and modeled results is carried out. Good agreement on the displacement curves and on the rise times is observed for all the range of controlling currents. ]]> 15 1 88 96 866 This paper describes a novel and compact topology for contactless levitation and rotation of a wide annular rotor through the walls of a sealed process chamber. In the proposed setup, a homopolar magnetic bearing biased by permanent magnets is combined with a high-pole-number segment motor. The paper discusses the functional principle of the motor, and gives design and optimization guidelines for the bearing and the drive unit, respectively. An experimental system is presented along with a set of measurement results verifying the theoretical considerations. ]]> 15 1 97 107 1342 Control of a robot manipulator in contact with the environment is usually conducted by a direct feedback control system using a force–torque sensor or an indirect impedance control scheme. Although these methods have been successfully applied to many applications, simultaneous control of force and position cannot be achieved. To cope with such problems, this paper proposes a novel design of a dual actuator unit (DAU) composed of two actuators and a planetary gear train to provide the capability of simultaneous control of position and stiffness. Since one actuator controls position and the other actuator modulates stiffness, the DAU can control the position and stiffness simultaneously at the same joint. Both the torque exerted on the joint and the stiffness of the environment can be estimated without an expensive force sensor. Various experiments demonstrate that the DAU can provide good performance for position tracking, force estimation, and environment estimation. ]]> 15 1 108 116 1039 The integration of computer-controlled electro-mechanical components in ground vehicle cooling systems can improve coolant temperature regulation and servomotor power consumption. Advanced thermal management systems for internal combustion engines can better regulate the combustion process by harmoniously controlling the cooling system's actuators to obtain desired thermal conditions in a power-efficient manner. In this paper, a comprehensive nonlinear control architecture is proposed for transient temperature tracking in multiple cooling circuits, which builds on single-loop studies. An experimental engine and transmission cooling system have been assembled that feature a variable-position smart thermostat valve, two variable-speed electric pumps, variable-speed electric radiator fan, engine block, transmission, radiator, steam-based heat exchanger, and sensors. Representative experimental results are discussed to demonstrate the functionality of the multiloop thermal management system under normal and elevated ambient temperatures. The presented results clearly show that the proposed robust controller-based thermal management system can accurately track prescribed engine and transmission temperature profiles. ]]> 15 1 117 124 790 This paper presents the development and performance assessment procedures for a new XY parallel micropositioning platform (PMP) aiming at a submicrometer accuracy for microscale manipulation. The uniqueness of the proposed microparallel platform lies in that it possesses an uncomplicated structure as well as actuation isolation and output motion decoupling properties, which facilitates the adoption of two single-input–single-output controllers. Based on the matrix method, the kinetostatics models of the PMP are established and verified by finite-element analysis. Via system identification, a digital lag--lead compensator is designed to compensate for the hysteresis of each piezoelectric actuator. A feedforward control is then implemented to construct a zero phase error tracking controller. Positioning performance of the PMP in terms of resolution, accuracy, repeatability, and contouring performances of 1-D and 2-D motions has been evaluated by several experimental studies. Experimental results not only validate the effectiveness of the designed controller but also show that both positioning and contouring of the PMP can achieve a submicrometer precision within a specified velocity range. ]]> 15 1 125 135 1373 In this paper, a novel inverse double nonlinear autoregressive with exogenous input (NARX) fuzzy model is applied to simultaneously model and identify both joints of the prototype two-axis pneumatic artificial muscle (PAM) robot arm's inverse dynamic model. Highly nonlinear features of both joints of the nonlinear manipulator system are identified by the proposed inverse double NARX fuzzy (IDNF) model based on experimental input–output training data. The modified genetic algorithm (GA) optimally generates the appropriate fuzzy if–then rules to perfectly characterize the dynamic features of the two-axis PAM manipulator system. The evaluation of different IDNF models with various ARX model structures will be discussed. For the first time, the nonlinear IDNF model of the two-axis PAM robot arm is investigated. The results show that the nonlinear IDNF model that is trained by GA performs better and has a higher accuracy than the conventional inverse fuzzy model. ]]> 15 1 136 148 1740 Conducting polymer bending actuators show potential for unique manipulation devices, particularly at the microscale, given low actuation voltages, controllable manufacture, biocompatibility, and ability to operate in either air or liquid environments; however, the impracticalities of implementing feedback in these environments and at these scales can impede positional control of the actuator. This paper presents an application of inversion-based feedforward positional control to a trilayer bender actuator, which is shown to improve the performance without the use of feedback or adjustments to the chemistry of the device. The step and dynamic displacement responses have all been improved under the feedforward control system, while the response does not change significantly under large increases in external loads. This study contributes the first implementation of inversion-based feedforward control to the emerging area of conducting polymer actuators, paving the way toward their use in functional devices, particularly where the implementation of feedback is difficult. ]]> 15 1 149 156 838 We describe a decision method for effective placement of tactile elements for grasp-type recognition. Not only does the placement decided by our method require a small number of tactile elements, it also achieves recognition performance as high as placements consisting of many elements. The placement decided by the method is evaluated through experiments involving the recognition of grasp type from the two types of grasp taxonomy defined by Cutkosky and Kamakura. The proposed method is extended by applying a decision tree pruning. The pruning is useful for reducing the number of selected tactile elements without badly dropping the recognition rate. ]]> 15 1 157 162 651 15 1 163 163 548 15 1 164 164 334 15 1 C3 C3 33 15 1 C4 C4 5