Development of a prototype of an ambient-aware two-arm mobile service robot

This paper describes a prototype of an ambient-intelligent advanced service robot of anthropomorphic characteristics that is intended for operation in indoor environment as well as for safe interaction with people. The robot consists of a wheeled mobile platform with a spinal (segmented) torso, bi-manual manipulation system with hands, and a robot head with capabilities to see, hear and speak. It is equipped with a number of advanced sensors, including indoor laser range finder, several ultrasonic probes as distance sensors and obstacle detectors, 3-axis inertial sensors with gyroscope, stereo vision system, 2 wide-range microphones, and 2 speakerphones. Its operation is autonomous but it may be controlled from a host computer through a wireless link. The robot prototype is expected to express advanced cognitive capabilities including spatial understanding, autonomous motion, affective and social behavior. The development of the robot is a joint effort of four Serbian academic institutions and it is expected to have it fully operational in the second half of 2015

A NOVEL METHODOLOGY FOR CHOOSING ACTUATORS OF CABLE-SUSPENDED PARALLEL ROBOTS

A novel methodology for choosing actuators of a CPR system was defined. This methodology was based on a novel procedure for analysis and synthesis of the workspace of Cable-suspended parallel robot, CPR system. Besides the kinematic and dynamic models of the CPR system, this procedure includes the complete mathematical model of the actuator as well. On this basis, this procedure presents a novel solution for the analysis and synthesis of CPR system’s workspace. When using the proposed methodology for choosing actuators of a CPR system, user and designer together define the corresponding technical requirements, one of them being the relative size of the feasible work space of the CPR system. Based on these requirements, the developed methodology tests available actuators from its data base and extracts the useful ones for the predefined specific purpose. The purpose of this research is to interconnect theoretical contributions from CPR system’s modelling and needs of the user and designer during their practical implementation. For this purpose, a user friendly program package called PPACM was generated. The program package PPACM and obtained results were validated through the presentation of several case studies

Vibration control of resonant vibratory feeders with electromagnetic excitation

Vibracioni dodavači sa elektromagnetnom pobudom, odnosno elektromagnetni vibracioni dodavači (EMVD) su najčešće korišćeni u procesnoj industriji za obezbeđenje gravimetrijskog protoka sitnozrnih i rasutih materijala. Ovi pogoni obezbeđuju laku i jednostavnu kontrolu masenog protoka transportujućih materijala. U poređenju sa ostalim pogonima (pneumatskim, inercionim, centrifugalnim, itd.), oni su jednostavnije i kompaktnije konstrukcije, robusni i pouzdani u radu. Odsustvo habajući mehaničkih delova kao što su reduktori, kišnici, ekscentri i sl., čine EMVD veoma ekonomičnom opremom. Standardni pretvarački izlazni stepeni namenjeni za kontrolu EMVD su bazirani na SCR elementima (tiristorima i trijacima). Njihovo korišćenje podrazumeva korišćenje kontrole faznog ugla (KFU) i stoga konstantnu učestanost vibracija. Na ovaj način kontrolno kolo mora biti sinhronizovano sa mrežnom učestanošću 50(60)Hz. Uz pomoć KFU je jedino moguće ostvariti podešavanje amplitude vibracija, ali ne i njihove učestanosti. Primena prekidačkih tranzistorskih (IGBT ili MOSFET) energetskih pretvarača, omogućava amplitudsku i (ili) frekventnu kontrolu EMVD. Njihovo korišćenje podrazumeva pobudu EMVD nezavisno od mrežne učestanosti. Dodatno, frekventna kontrola dozvoljava rad u oblasti mehaničke rezonance. Rad u ovoj oblasti je veoma efikasan, pošto je moguće obezbediti značajne izlazne pomeraje, veoma malom ulaznom snagom. Optimalan i efikasan rad zahteva praćenje rezonantne učestanosti. U ovom radu su predstavljeni jedno moguće rešenje vibracione kontrole EMVD, kao i odgovarajući simulacioni i eksperimentalni rezultati.The vibratory feeders with electromagnetic excitation called electromagnetic vibratory feeders (EMVF) are commonly used for performing gravimetric flow of granular and particulate materials in processing industry. This drives offer easy and simple control the mass flow of conveying materials. In comparison with other drives (pneumatics, inertial, centrifugal, etc...), these have a more simple construction and they are compact, robust and reliable in operation. The absence of wearing mechanical part, such as gears, cams belts, bearings, eccentrics, etc., makes EMVF, most economical equipment. Standard power electronic output stages intended for control of the EMVF using SCR devices (thyristors and triacs). This implies phase angle control (PAC) and constant frequency of vibration. In this way control circuit must be synchronized to the mains supply frequency 50(60) Hz. PAC can only accomplish tuning amplitude of vibration, but not vibratory frequency. Application of transistor (IGBT or MOSFET) switch mode power converters enables accomplishing the amplitude and (or) frequency control of EMVF. Their use implies the excitation of an EMVF independent of the mains supply frequency. In addition, the frequency control ensures operation in the region of mechanical resonance. This operation is highly efficient, because large output displacement is provided by small input power. An optimal and efficient operation requires tracking of resonant frequency. This paper presents possible solution of the amplitude frequency control of EMVF and corresponding simulation and experimental results

Vibration control of resonant vibratory feeders with electromagnetic excitation

Vibracioni dodavači sa elektromagnetnom pobudom, odnosno elektromagnetni vibracioni dodavači (EMVD) su najčešće korišćeni u procesnoj industriji za obezbeđenje gravimetrijskog protoka sitnozrnih i rasutih materijala. Ovi pogoni obezbeđuju laku i jednostavnu kontrolu masenog protoka transportujućih materijala. U poređenju sa ostalim pogonima (pneumatskim, inercionim, centrifugalnim, itd.), oni su jednostavnije i kompaktnije konstrukcije, robusni i pouzdani u radu. Odsustvo habajući mehaničkih delova kao što su reduktori, kišnici, ekscentri i sl., čine EMVD veoma ekonomičnom opremom. Standardni pretvarački izlazni stepeni namenjeni za kontrolu EMVD su bazirani na SCR elementima (tiristorima i trijacima). Njihovo korišćenje podrazumeva korišćenje kontrole faznog ugla (KFU) i stoga konstantnu učestanost vibracija. Na ovaj način kontrolno kolo mora biti sinhronizovano sa mrežnom učestanošću 50(60)Hz. Uz pomoć KFU je jedino moguće ostvariti podešavanje amplitude vibracija, ali ne i njihove učestanosti. Primena prekidačkih tranzistorskih (IGBT ili MOSFET) energetskih pretvarača, omogućava amplitudsku i (ili) frekventnu kontrolu EMVD. Njihovo korišćenje podrazumeva pobudu EMVD nezavisno od mrežne učestanosti. Dodatno, frekventna kontrola dozvoljava rad u oblasti mehaničke rezonance. Rad u ovoj oblasti je veoma efikasan, pošto je moguće obezbediti značajne izlazne pomeraje, veoma malom ulaznom snagom. Optimalan i efikasan rad zahteva praćenje rezonantne učestanosti. U ovom radu su predstavljeni jedno moguće rešenje vibracione kontrole EMVD, kao i odgovarajući simulacioni i eksperimentalni rezultati.The vibratory feeders with electromagnetic excitation called electromagnetic vibratory feeders (EMVF) are commonly used for performing gravimetric flow of granular and particulate materials in processing industry. This drives offer easy and simple control the mass flow of conveying materials. In comparison with other drives (pneumatics, inertial, centrifugal, etc...), these have a more simple construction and they are compact, robust and reliable in operation. The absence of wearing mechanical part, such as gears, cams belts, bearings, eccentrics, etc., makes EMVF, most economical equipment. Standard power electronic output stages intended for control of the EMVF using SCR devices (thyristors and triacs). This implies phase angle control (PAC) and constant frequency of vibration. In this way control circuit must be synchronized to the mains supply frequency 50(60) Hz. PAC can only accomplish tuning amplitude of vibration, but not vibratory frequency. Application of transistor (IGBT or MOSFET) switch mode power converters enables accomplishing the amplitude and (or) frequency control of EMVF. Their use implies the excitation of an EMVF independent of the mains supply frequency. In addition, the frequency control ensures operation in the region of mechanical resonance. This operation is highly efficient, because large output displacement is provided by small input power. An optimal and efficient operation requires tracking of resonant frequency. This paper presents possible solution of the amplitude frequency control of EMVF and corresponding simulation and experimental results

Kinematics of the MIT-AI-VICARM Manipulator

This report describes research done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for the laboratory's artificial intelligence research is provided in part by the Advanced Research Projects Agency of the Department of Defense under Office of Naval Research contract N00014-70-A-0362-0005.This paper describes the basic geometry of the electric manipulator designed for the Artificial Intelligence Laboratory by Victor Scheinman while on leave from Stanford University. The procedure for finding a set of joint angles that will place the terminal device in a desired position and orientation is developed in detail. This is on of the basic primitives that an arm controller should have. The orientation is specified in terms of Euler-angles. Typically eight sets of joint angles will produce the same terminal device position and orientation.MIT Artificial Intelligence Laborator

Experimental determination of mechanical properties of cylindrical samples made by additive technology

This paper presents experimental results in determining the mechanical properties of cylindrical samples made by additive technology. In the past, additive technologies were used only for prototypes. Today, they are actively involved in the production, especially in the case of small series or parts with special geometric and mechanical requirements—the tested samples were cylindrical and printed on a printer German Rep Rap X400 (It is important to note that, during the test, the samples were not treated with acetone). The German Rep Rap X400 is an Industrial Quality 3D Printer with high precision, speed and printing volume. The test was performed in the control of displacement at a speed of 1 [mm/min], while the layer's height was 0.2 [mm]. The substrate temperature was 100oC, while the nozzle temperature was 245oC. The results presented in this paper can be used and are repeatable in practice and in further research

Experimental determination of mechanical properties of cylindrical samples made by additive technology

This paper presents experimental results in determining the mechanical properties of cylindrical samples made by additive technology. In the past, additive technologies were used only for prototypes. Today, they are actively involved in the production, especially in the case of small series or parts with special geometric and mechanical requirements—the tested samples were cylindrical and printed on a printer German Rep Rap X400 (It is important to note that, during the test, the samples were not treated with acetone). The German Rep Rap X400 is an Industrial Quality 3D Printer with high precision, speed and printing volume. The test was performed in the control of displacement at a speed of 1 [mm/min], while the layer's height was 0.2 [mm]. The substrate temperature was 100oC, while the nozzle temperature was 245oC. The results presented in this paper can be used and are repeatable in practice and in further research

Radon exhalation from fly-ash geopolymer mortar

Geopolymers are a type of alkali activated binders, inorganic aluminosilicate polymers with amorphous cross-linked structure. Fly-ash is produced in abundance during coal firing, and poses an environmental and health risk in untreated powder form. Fly-ash geopolymer presents a sustainable alternative to Portland cement, due to lower net greenhouse gas emissions. Presence of naturally occurring radioactive elements in fly-ash is one of the factors taken into account when estimating the safety of fly-ash based building materials. Radon, a radioactive noble gas originating from the decay of radium, can leave the material and contribute to internal dose in closed spaces, so radon exhalation is of special interest. Radon exhalation for a standard sample of fly-ash geopolymer mortar was measured

ASME 88-1CE-6, presented at the Energy-Source Technology Conference and Exhibition

Fig. 5 Velocity versus anguiar dispiacement (V8 engine) attained from the inertia value using the least squares method is consistently smaller than the reference data, and eventually leads to larger velocity estimation error than the average method Some precautions are needed when applying the least squares method to compute the engine inertia value. For engines operating at high speeds, the velocity related term in Eq. (1) could be very large compared with the other terms. This could result in some confusing situations. For instance, engines might decelerate over some portion of the engine operation cycle while the net external torque accelerating the engine is positive; or engines might accelerate while the net external torque is negative. These operation situations might make negative engine inertia value estimations possible, which is not feasible. In other cases, engines might have very small accelerations or decelerations while net external torque is moderate to large. For these cases, the calculation might lead to very large engine inertia values, which is not feasible either. The cases mentioned above are most likely to occur when engines operate at high speeds. Those erroneous data corresponding the situations above must be Altered out before applying the least squares method to the engine inertia value computation. The criterion used in this study to decide whether data should be used to calculate the engine inertia values is to check the quotient of the net external torque divided by the engine acceleration. This quotient should not be too large or too small relative to the average engine inertia value. Those data whose quotient are significantly away from the average engine inertia value are likely to fall in the situations mentioned above, and those data should not be used in the engine inertia value computation. V Conclusions The engine inertia values calculated by the least squares method guarantees minimum acceleration and velocity estimation errors for engine operating at constant average velocities. As for monotonically accelerating and decelerating engines, simulations in the study show that the engine model with an inertia calculated by the least squares method leads to smaller estimation errors in acceleration but larger estimation errors in velocity than the constant inertia engine model with an average inertia. It is important that the user knows the type of engine, its range of operation, and the type of loading in order to calculate an optimal engine inertia for the control purpose. This study has provided guidance in understanding the effects of engine performance variables and in calculating an appropriate estimate for the engine inertia. Acknowledgment