The development of tolerance in Pseudomonas putida DOT-T1 to toluene and related highly toxic com... more The development of tolerance in Pseudomonas putida DOT-T1 to toluene and related highly toxic compounds involves short-and long-term responses. The short-term response is based on an increase in the rigidity of the cell membrane by rapid transformation of the fatty acid cis-9,10-methylene hexadecanoic acid (C17:cyclopropane) to unsaturated 9-cis-hexadecenoic acid (C16:1,9 cis) and subsequent transformation to the trans isomer. The long-term response involves in addition to the changes in fatty acids, alterations in the level of the phospholipid polar head groups: cardiolipin increases and phosphatidylethanolamine decreases. The two alterations lead to increased cell membrane rigidity and should be regarded as physical mechanisms that prevent solvent penetrance. Biochemical mechanisms that decrease the concentration of toluene in the cell membrane also take place and involve: (i) a solvent exclusion system and (ii) metabolic removal of toluene via oxidation. Mutants unable to carry out cis 3 trans isomerization of unsaturated lipids, that exhibit altered cell envelopes because of the lack of the OprL protein, or that are unable to exclude toluene from cell membranes are hypersensitive to toluene.
This paper describes the experimental comparison among four model-based control algorithms on a d... more This paper describes the experimental comparison among four model-based control algorithms on a direct-drive robotic arm. We present experimental results of the following controllers: Computed-Torque control, PD+ control, PD control with computed feedforward and PD control. All controllers include Coulomb and viscous friction compensation as well as cancellation of gravitational torques. They are tested under common trajectory speci®cation and performance index. 7
International Journal of Adaptive Control and Signal Processing, 1998
In this paper we propose a framework to adaptive regulator design of robot manipulators. A class ... more In this paper we propose a framework to adaptive regulator design of robot manipulators. A class of global regulators for robot is characterized for which we provide guidelines to derive adaptive versions. The class of regulators is described by control laws comprising the gradient of ...
International Journal of Imaging Systems and Technology, 2000
Abstract Vision system calibration and identification are important issues for effective implemen... more Abstract Vision system calibration and identification are important issues for effective implementation of high-performance robotic systems. Vision system identification addresses the problem of determining the mapping from points in the world frame to their ...
This paper is focused on estimating the dynamic parameters of robot manipulators. A new hybrid id... more This paper is focused on estimating the dynamic parameters of robot manipulators. A new hybrid identification scheme based on the supplied energy regression model is proposed. Experimental results on a two degrees of freedom direct-drive robot are presented
In this paper, the control problem of camera-in-hand robotic systems is considered. In this appro... more In this paper, the control problem of camera-in-hand robotic systems is considered. In this approach, a camera is mounted on the robot, usually at the hand, which provides an image of objects located in the robot environment. The aim of this approach is to move the robot arm in such a way that the image of the objects attains the desired locations. We propose a simple image-based direct visual servo controller which requires knowledge of the objects' depths, but it does not need to use the inverse kinematics and the inverse Jacobian matrix. By invoking the Lyapunov direct method, we show that the overall closed-loop system is stable and, under mild conditions on the Jacobian, local asymptotic stability is guaranteed. Experiments with a two degrees-of-freedom direct-drive manipulator are presented to illustrate the controller's performance.
International Journal of Adaptive Control and Signal Processing, 1996
In this paper we propose a new adaptive controller for the global regulation of robot manipulator... more In this paper we propose a new adaptive controller for the global regulation of robot manipulators. This controller incorporates adaptation of the gravitational torque vector to overcome parametric uncertainties in the robot and payload such as masses and inertia. Also, ...
In this paper, we propose a simple controller for set-point control of robot manipulators. The st... more In this paper, we propose a simple controller for set-point control of robot manipulators. The structure of this controller is composed by a saturated proportional-saturated derivative feedback plus gravity compensation. Such a control scheme has two practical features. First, for all desired joint positions, this controller delivers torques inside prescribed limits according to the actuator capability and second, the steadystate position errors owing to static friction can be arbitrarily reduced. In the case of absence of friction, we show global asymptotic stability of the closed-loop system. The performance of the proposed controller is illustrated via experiments on a two-degrees-of-freedom (2-DOF) direct-drive robot system.
Fernando Reyes ECE-Universidad Aut6noma de Puebla Apdo. Postal 1651 Tel/FAX: +52 (22) 33 19 20 Pu... more Fernando Reyes ECE-Universidad Aut6noma de Puebla Apdo. Postal 1651 Tel/FAX: +52 (22) 33 19 20 Puebla, Puebla, 72000, MEXICO. e-mail: freyes6lkim.ece.buap.m ... This paper addresses the visual servoing of robot manipulators in fixed-camera configuration.
This paper describes the experimental evaluation of three identification schemes to determine the... more This paper describes the experimental evaluation of three identification schemes to determine the dynamic parameters of a two degrees of freedom direct-drive robot. These schemes involve a recursive estimator while the regression models are formulated in continuous time. The ...
The increased demand for enzymes with new properties makes indispensable the development of easy ... more The increased demand for enzymes with new properties makes indispensable the development of easy and rapid strategies to obtain complete genes of new enzymes. Here a strategy is described which includes screening by PCR of new subtilases mediated by Consensus-Degenerate Hybrid Oligonucleotide Primers (CODEHOP) and an improved genome walking method to obtain the complete sequence of the identified genes. Existing methods of genome walking have many limitations, which make them inefficient and time consuming. We have developed an improved genome walking method with novel advances to get a simple, rapid and more efficient procedure based on cassette-ligation. Improvements consist basically in the possibility of a genomic DNA digestion with any restriction enzyme, blunting and 3' adenylation of digested DNA by Taq DNA polymerase to avoid self-circularization, followed by TA ligation of the adenine 3' overhanging end to the same unphosphorylated oligo-cassette. The efficiency of the genome walking method was demonstrated by finding the unknown ends of all gene fragments tested, previously obtained by CODEHOP-mediated PCR, including three subtilases (P4, P6 and P7), one xylanase and one lipase, from different strains of Antarctic marine bacteria.
The development of tolerance in Pseudomonas putida DOT-T1 to toluene and related highly toxic com... more The development of tolerance in Pseudomonas putida DOT-T1 to toluene and related highly toxic compounds involves short-and long-term responses. The short-term response is based on an increase in the rigidity of the cell membrane by rapid transformation of the fatty acid cis-9,10-methylene hexadecanoic acid (C17:cyclopropane) to unsaturated 9-cis-hexadecenoic acid (C16:1,9 cis) and subsequent transformation to the trans isomer. The long-term response involves in addition to the changes in fatty acids, alterations in the level of the phospholipid polar head groups: cardiolipin increases and phosphatidylethanolamine decreases. The two alterations lead to increased cell membrane rigidity and should be regarded as physical mechanisms that prevent solvent penetrance. Biochemical mechanisms that decrease the concentration of toluene in the cell membrane also take place and involve: (i) a solvent exclusion system and (ii) metabolic removal of toluene via oxidation. Mutants unable to carry out cis 3 trans isomerization of unsaturated lipids, that exhibit altered cell envelopes because of the lack of the OprL protein, or that are unable to exclude toluene from cell membranes are hypersensitive to toluene.
This paper describes the experimental comparison among four model-based control algorithms on a d... more This paper describes the experimental comparison among four model-based control algorithms on a direct-drive robotic arm. We present experimental results of the following controllers: Computed-Torque control, PD+ control, PD control with computed feedforward and PD control. All controllers include Coulomb and viscous friction compensation as well as cancellation of gravitational torques. They are tested under common trajectory speci®cation and performance index. 7
International Journal of Adaptive Control and Signal Processing, 1998
In this paper we propose a framework to adaptive regulator design of robot manipulators. A class ... more In this paper we propose a framework to adaptive regulator design of robot manipulators. A class of global regulators for robot is characterized for which we provide guidelines to derive adaptive versions. The class of regulators is described by control laws comprising the gradient of ...
International Journal of Imaging Systems and Technology, 2000
Abstract Vision system calibration and identification are important issues for effective implemen... more Abstract Vision system calibration and identification are important issues for effective implementation of high-performance robotic systems. Vision system identification addresses the problem of determining the mapping from points in the world frame to their ...
This paper is focused on estimating the dynamic parameters of robot manipulators. A new hybrid id... more This paper is focused on estimating the dynamic parameters of robot manipulators. A new hybrid identification scheme based on the supplied energy regression model is proposed. Experimental results on a two degrees of freedom direct-drive robot are presented
In this paper, the control problem of camera-in-hand robotic systems is considered. In this appro... more In this paper, the control problem of camera-in-hand robotic systems is considered. In this approach, a camera is mounted on the robot, usually at the hand, which provides an image of objects located in the robot environment. The aim of this approach is to move the robot arm in such a way that the image of the objects attains the desired locations. We propose a simple image-based direct visual servo controller which requires knowledge of the objects' depths, but it does not need to use the inverse kinematics and the inverse Jacobian matrix. By invoking the Lyapunov direct method, we show that the overall closed-loop system is stable and, under mild conditions on the Jacobian, local asymptotic stability is guaranteed. Experiments with a two degrees-of-freedom direct-drive manipulator are presented to illustrate the controller's performance.
International Journal of Adaptive Control and Signal Processing, 1996
In this paper we propose a new adaptive controller for the global regulation of robot manipulator... more In this paper we propose a new adaptive controller for the global regulation of robot manipulators. This controller incorporates adaptation of the gravitational torque vector to overcome parametric uncertainties in the robot and payload such as masses and inertia. Also, ...
In this paper, we propose a simple controller for set-point control of robot manipulators. The st... more In this paper, we propose a simple controller for set-point control of robot manipulators. The structure of this controller is composed by a saturated proportional-saturated derivative feedback plus gravity compensation. Such a control scheme has two practical features. First, for all desired joint positions, this controller delivers torques inside prescribed limits according to the actuator capability and second, the steadystate position errors owing to static friction can be arbitrarily reduced. In the case of absence of friction, we show global asymptotic stability of the closed-loop system. The performance of the proposed controller is illustrated via experiments on a two-degrees-of-freedom (2-DOF) direct-drive robot system.
Fernando Reyes ECE-Universidad Aut6noma de Puebla Apdo. Postal 1651 Tel/FAX: +52 (22) 33 19 20 Pu... more Fernando Reyes ECE-Universidad Aut6noma de Puebla Apdo. Postal 1651 Tel/FAX: +52 (22) 33 19 20 Puebla, Puebla, 72000, MEXICO. e-mail: freyes6lkim.ece.buap.m ... This paper addresses the visual servoing of robot manipulators in fixed-camera configuration.
This paper describes the experimental evaluation of three identification schemes to determine the... more This paper describes the experimental evaluation of three identification schemes to determine the dynamic parameters of a two degrees of freedom direct-drive robot. These schemes involve a recursive estimator while the regression models are formulated in continuous time. The ...
The increased demand for enzymes with new properties makes indispensable the development of easy ... more The increased demand for enzymes with new properties makes indispensable the development of easy and rapid strategies to obtain complete genes of new enzymes. Here a strategy is described which includes screening by PCR of new subtilases mediated by Consensus-Degenerate Hybrid Oligonucleotide Primers (CODEHOP) and an improved genome walking method to obtain the complete sequence of the identified genes. Existing methods of genome walking have many limitations, which make them inefficient and time consuming. We have developed an improved genome walking method with novel advances to get a simple, rapid and more efficient procedure based on cassette-ligation. Improvements consist basically in the possibility of a genomic DNA digestion with any restriction enzyme, blunting and 3' adenylation of digested DNA by Taq DNA polymerase to avoid self-circularization, followed by TA ligation of the adenine 3' overhanging end to the same unphosphorylated oligo-cassette. The efficiency of the genome walking method was demonstrated by finding the unknown ends of all gene fragments tested, previously obtained by CODEHOP-mediated PCR, including three subtilases (P4, P6 and P7), one xylanase and one lipase, from different strains of Antarctic marine bacteria.
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