22 research outputs found
Collision-free inverse kinematics of the redundant seven-link manipulator used in a cucumber picking robot
The paper presents results of research on an inverse kinematics algorithm that has been used in a functional model of a cucumber-harvesting robot consisting of a redundant P6R manipulator. Within a first generic approach, the inverse kinematics problem was reformulated as a non-linear programming problem and solved with a Genetic Algorithm (GA). Although solutions were easily obtained, the considerable calculation time needed to solve the problem prevented on-line implementation. To circumvent this problem, a second, less generic, approach was developed which consisted of a mixed numerical-analytic solution of the inverse kinematics problem exploiting the particular structure of the P6R manipulator. Using the latter approach, calculation time was considerably reduced. During the early stages of the cucumber-harvesting project, this inverse kinematics algorithm was used off-line to evaluate the ability of the robot to harvest cucumbers using 3D-information obtained from a cucumber crop in a real greenhouse. Thereafter, the algorithm was employed successfully in a functional model of the cucumber harvester to determine if cucumbers were hanging within the reachable workspace of the robot and to determine a collision-free harvest posture to be used for motion control of the manipulator during harvesting. The inverse kinematics algorithm is presented and demonstrated with some illustrative examples of cucumber harvesting, both off-line during the design phase as well as on-line during a field test
Collision-free inverse kinematics of a 7 link cucumber picking robot
The paper presents results of research on inverse kinematics algorithms to be used in a functional model of a cucumber harvesting robot consisting of a redundant manipulator with one prismatic and six rotational joints (P6R). Within a first generic approach, the inverse kinematics problem was reformulated as a non-linear programming problem and solved with a generic algorithm. Solutions were easily obtained, but the considerable calculation time needed to solve the problem prevented on line implementation. To circumvent this problem, a second, less generic approach was developed consisting of a mixed numerical-analytic solution of the inverse kinematics problem exploiting the particular structure of the P6R manipulator. This approach facilitated rapid and robust calculation of the inverse kinematics of the cucumber harvester. During the early stages of the cucumber harvesting project, this inverse kinematics algorithm was used to off-line evaluate the ability of the robot to harvest cucumbers using 3D-information of a cucumber crop obtained in a real greenhouse. Thereafter, the algorithm was employed successfully in a functional model of the cucumber harvester to determine if cucumbers were hanging within the reachable workspace of the robot and to determine a collision-free harvest posture to be used for motion control of the manipulator during harvesting
Androgen Deficiency Symptoms in Testicular Cancer Survivors Are Associated With Sexual Problems but Not With Serum Testosterone or Therapy: Comment
Y-deletions in men with severe oligospermia
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Direct arterial anastomosis on corpora cavernosal penis in the therapy of erectile impotence. V. Michal, R. Kramar, J. Pospichal, and L. Hejhal
Transurethral deroofing of midline prostatic cyst for subfertile men
We evaluated the efficacy of transurethral deroofing of a midline
prostatic cyst in subfertile men with one or more of the following semen
abnormalities: decreased ejaculatory volume, decreased sperm motility and
oligo- or azoospermia. Results from treatment of a series of 11 subfertile
men with a midline prostatic cyst by transurethral deroofing of the cyst
are presented. Five patients showed an improvement of seminal volume. Only
one patient demonstrated an improvement of sperm count. Sperm motility was
not influenced. No relationship was found between positive outcome
following operation and either size of the cyst or dilatation of the
seminal vesicles. Spontaneous pregnancies did not occur after
transurethral deroofing of the midline prostatic cyst. In conclusion, our
study suggests a poor efficacy of transurethral deroofing of a midline
prostatic cyst in subfertile men with the above mentioned semen
abnormalities
Collision-free inverse kinematics of a 7 link cucumber picking robot
The paper presents results of research on inverse kinematics algorithms to be used in a functional model of a cucumber harvesting robot consisting of a redundant manipulator with one prismatic and six rotational joints (P6R). Within a first generic approach, the inverse kinematics problem was reformulated as a non-linear programming problem and solved with a generic algorithm. Solutions were easily obtained, but the considerable calculation time needed to solve the problem prevented on line implementation. To circumvent this problem, a second, less generic approach was developed consisting of a mixed numerical-analytic solution of the inverse kinematics problem exploiting the particular structure of the P6R manipulator. This approach facilitated rapid and robust calculation of the inverse kinematics of the cucumber harvester. During the early stages of the cucumber harvesting project, this inverse kinematics algorithm was used to off-line evaluate the ability of the robot to harvest cucumbers using 3D-information of a cucumber crop obtained in a real greenhouse. Thereafter, the algorithm was employed successfully in a functional model of the cucumber harvester to determine if cucumbers were hanging within the reachable workspace of the robot and to determine a collision-free harvest posture to be used for motion control of the manipulator during harvesting