Design and control of a robotic cable-suspended camera system for operation in 3-D industrial environment

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (leaves 52-54).Cable-suspended robots offer many advantages over conventional serial manipulators. The main benefit of cable robots is their large workspace size, which makes them well suited for broadcasting, transporting/loading, and construction applications. Since cables can only pull and not push the end-effector however, designing and controlling cable robots becomes more challenging. This thesis describes the design of a three-cable underconstrained robot which was built and then tested using a velocity feedback loop with a built-in PI controller. The endeffector of the robot consists of a camcorder mounted on a platform. The objective of the robot is to manipulate the camcorder in 3-D space with minimal tracking error. The dynamic equations of the system are derived along with the kinematic relationships and a closed-loop controller is designed. The controller is tested by prescribing a trajectory to the end-effector. Simulink derives the motor velocities given the desired Cartesian positions of the end-effector and simultaneously controls all three motors. The results of the experiment show that the error in the trajectory, which is on the order of about seven centimeters in the x -y plane, is small compared to the size of the robot's workspace. However, depending on the required precision, improvements may have to be made to the robot to reduce error. Future research ideas are presented to expand the scope of the robot.by Vladimir Gordievsky.S.B

Low Mobility Cable Robot with Application to Robotic Warehousing

Cable-based robots consist of a rigid mobile platform connected via flexible links (cables, wires, tendons) to a surrounding static platform. The use of cables simplifies the mechanical structure and reduces the inertia, allowing the mobile platform to reach high motion acceleration in large workspaces. These attributes give, in principle, an advantage over conventional robots used for industrial applications, such as the pick and place of objects inside factories or similar exterior large workspaces. However, unique cable properties involve new theoretical and technical challenges: all cables must be in tension to avoid collapse of the mobile platform. In addition, positive tensions applied to cables may affect the overall stiffness, that is, cable stretch might result in unacceptable oscillations of the mobile platform. Fully constrained cable-based robots can be distinguished from other types of cable-based robots because the motion and force generation of the mobile platform is accomplished by controlling both the cable lengths and the positive cable tensions. Fully constrained cable-based robots depend on actuator redundancy, that is, the addition of one or more actuated cables than end-effector degrees of freedom. Redundancy has proved to be beneficial to expand the workspace, remove some types of singularities, increase the overall stiffness, and support high payloads in several proposed cable-based robot designs. Nevertheless, this strategy demands the development of efficient controller designs for real-time applications. This research deals with the design and control of a fully constrained cable-based parallel manipulator for large-scale high-speed warehousing applications. To accomplish the design of the robot, a well-ordered procedure to analyze the cable tensions, stiffness and workspace will be presented to obtain an optimum structure. Then, the control problem will be investigated to deal with the redundancy solution and all-positive cable tension condition. The proposed control method will be evaluated through simulation and experimentation in a prototype manufactured for testing

A Cable-Driven Parallel Robot with an Embedded Tilt-Roll Wrist

International audienceThis paper addresses the optimum design, configuration and workspace analysis of a Cable-Driven Parallel Robot (CDPR) with an embedded tilt-roll wrist. The manipulator consists in a tilt-roll wrist mounted on the moving platform of a suspended CDPR. The embedded wrist provides large amplitudes of tilt and roll rotations and a large translational workspace obtained by the CDPR. This manipulator is suitable for tasks requiring large rotation and translation workspaces like tomography scanning, camera-orienting devices and visual surveillance. The moving-platform is an eight-degree-of-freedom articulated mechanism with large translational and rotational workspaces and it is suspended from a fixed frame by six cables. The manipulator employs two bi-actuated cables, i.e., cable loops to transmit the power from motors fixed on the ground to the tilt-roll wrist. Therefore, the manipulator achieves better dynamic performances due to a lower inertia of its moving-platform

Vaijeridronen suunnittelu ja toteutus

Tiivistelmä. Tämän diplomityön tavoitteena on suunnitella ja kehittää vaijeridrone, jota on tarkoitus käyttää sekä sisätiloissa että ulkoilmassa. Vaijeridronella tullaan suorittamaan ympäristön tarkkailua siihen kiinnitettävän kameran ja muiden mittausantureiden avulla. Laitteesta pyritään luomaan ainakin edestakaisin liikkuva ja lisäksi liikettä pyritään laajentamaan sekä sivuttais- että pystysuunnassa. Työn teoriaosassa käydään läpi robotiikkaa yleisesti ja lisäksi tarkastellaan olemassa olevia kaupallisia sekä prototyyppitasolla olevia vaijerikameraratkaisuja. Teoriaosuudessa käydään läpi myös eri materiaalivaihtoehtoja kulkuvaijeria varten. Teoriaosuuden lopussa käsitellään robotteihin liittyvää kinematiikkaa. Työn toteutusosassa esitellään kulkuvaijerin valinta laitetta varten. Vaijeridronen liikkuminen pisteestä pisteeseen mahdollistetaan vaijereiden pituuksia säätämällä ja pituuksien määrittämistä varten tarvittava laskenta käydään läpi käänteiskinematiikan muodossa. Työssä toteutetaan myös prototyyppilaitetta varten tarvittavien moottoreiden mitoitus ja valinta. Työn loppuosassa käydään läpi mekaniikkasuunnittelu ja esitetään toteutus, jolla moottorit saadaan liitettyä kelojen yhteyteen. Työn tuloksena saatiin toteutettua kaksi erilaista vaijeridronejärjestelmää. Ensimmäisenä ratkaisuna on hankittu kaupallinen vaijeridrone. Toisena ratkaisuna työssä on kehitetty harjattomilla tasavirtamoottoreilla ja niihin kytketyillä keloilla ohjattava 2D-vaijeridrone, jolla voidaan simuloida tavallisen dronen lentoa tasotapauksessa. Laite saatiin toteutettua siten, että kela-moottoriyhdistelmät ja kelojen sisältämä vaijeri pystyttiin kiinnittämään itse prototyypin runkoon.Design and implementation of a cable drone. Abstract. The aim of this Master’s thesis is to design and develop a cable drone, which will be used both indoors and outdoors. Cable drone will be used to observe the environment with the help of camera and other measuring sensors attached to it. The target is to create at least back and forth moving device and if possible, to expand the movement both laterally and vertically. In the theoretical part of this thesis robotics is reviewed generally and existing commercial cable cameras and prototype solutions are considered. Different material options for the cable are also considered in the theoretical part. In the end of this part kinematics related to robots is discussed. In the practical part of the thesis the cable selection for the device is presented. The movement of a cable drone from point to point is made possible by changing the lengths of the cables and the calculation required to determine these lengths is carried out by inverse kinematics. The thesis also involves the dimensioning and selection of motors for the desired prototype. At the end of the thesis the mechanical design is reviewed as well as the construction, where the motors are attached to the reels. As the result of the thesis two different cable drone systems were accomplished. As a first solution a commercial cable camera has been bought. As a second solution 2D cable drone system, controlled by brushless DC motors with round reels attached to them, has been developed. This system can be used to simulate the flight of a normal drone in a plane. The device was designed so that the motor-round reel assemblies and the cable could be attached to the prototype’s body itself