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Task Description
Final report
Last updated:
January 29, 2002

Coordinated by:
Basilio Bona

Optimized Structures and
Intelligent Control Architecture
for Space Manipolators
with Flexible Arms

funded by ASI-ARS contract 99-38

Dipartimento di Automatica e Informatica, DAUIN-TO, Politecnico di Torino

Dipartimento di Elettronica, DELEN-TO, Politecnico di Torino
Dipartimento di Meccanica, DIMEC-TO, Politecnico di Torino
Dipartimento di Informatica e Automazione, DIA-RO3, Università di Roma Tre


Task Description

The ASI-ARS 99-38 contract is relative to the third and last year of a coordinate research project, whose goal is the construction of a flexible robot arm prototype, equipped by a motor and integrated with an intelligent control architecture, to study the various matters related to flexible robots control. The carried out research dealt with both the mechanical and control aspects, with the design and implementation of the control electronics, and finally with the development of a complete simulator of the plant. Graphical techniques have been studied also for 3D simulation, to be used as an aid to the operator for a subsequent remote control (teleoperation) of the robot arm.

During the first six months of the research activity, the flexible link prototype has been assembled, and a complete simulator has been developed in the Simulink environment (mainly by the DAUIN-TO and DIMEC-TO groups). An easy substitution of the flexible beam and/or the addition of a payload (possibly a second link, with its actuator) are allowed by construction. Electromagnetic proof mass dampers have then been studied and constructed by the DIMEC-TO group, to be alternatively used instead of the piezoelectric transducers currently employed. A devoted test rig has been constructed, to test their effectiveness before using them in the flexible link prototype.

From the control point of view, the DAUIN-TO group has studied different schemes for the control of the flexible link, by following the LQG, LTR and approaches, and tested them (even if presently only by simulation); previous studies about impact control have been extended and completed in collaboration with the DIA-RO3 group, also experimentally by using a test-bed that is available in the laboratories of Università di Roma Tre.

The DELEN-TO group has provided detailed specifications of a high-level co-design environment for programmable control systems, by using well-known languages both for the design environment, such as Matlab/Simulink, and for the hardware description, as VHDL. A detailed project of a DSP/PLD based control system has also been developed.

The DIA-RO3 unit has finally developed a 3D graphical simulator, to be used as an aid to the operator for the remote control of the manipulator, by employing the Internet network for the data transmission.

In the remainder of the this document, a detailed description of the research activity is provided by the single units that mainly dealt with the various aspects.


  1. DAUIN-TO Coordinator Prof. Basilio Bona

    The research activity of the DAUIN-TO group, during the first period of the ASI ARS-99-38 grant, has been mainly devoted to the following topics:
    1. Development of a complete dynamic model for the experimental set up of a flexible robot link, equipped by concentrated and distributed actuators (together with the DIMEC-TO research unit, in cooperation with Centro Servizi di Prototipazione of Politecnico di Torino).
    2. Study and design of control schemes for flexible robot links, according to different approaches (in the time domain and in the frequency one).
    3. Study and experimental implementation of schemes for the impact control of links, that are approximately considered as rigid, and evaluation of the influence of the actual structure elasticity (in cooperation with the DIA-RO3 research unit).
    4. Development of HW and SW interfaces between the OpenDSP environment and the joint actuator of the flexible link prototype, for the implementation of the control architecture.

  2. DELEN-TO Coordinator Prof. Dante Del Corso

    The work carried on in the first six months, was essentially based on two main points:
    - detailed specifications of a high-level co-design environment for programmable control systems
    - detailed project of a DSP/PLD based control system

    About the first point, we developed the specifications of a high-level design environment for hardware/software programmable platforms.

    This choice was made concurrently with the design of a general purpose control system based on programmable logic devices (PLD) and commercial DSPs: this platform allows more flexibility than others (based on custom VLSI devices, original project) when used to implement programmable control architectures (classic and neuro-fuzzy).

    The DSP/PLD board can also be used to test VLSI devices with good accuracy: in fact it is possible to download on programmable devices the same control architectures implemented on custom VLSI chips. This approach requires high level description tools and languages (VHDL for example) also for VLSI chip synthesis.

  3. DIMEC-TO Coordinator Prof. Giancarlo Genta

    The main research themes developed by Dipartimento di Meccanica of Politecnico di Torino during the first semester of the contract ASI n. ARS-99-38 concern the following subjects:
    - Finite elements models of flexible links equipped with "active constrained layer dampers" (ACLD).
    - Modal reduction techniques and integration of the centrifugal and Coriolis effects acting on the rotating arm into its FEM model.
    - Design and construction of electromagnetic proof mass dampers.
    - Design and construction of a test rig including a clamped beam of modular configuration with piezoelectric transducers and electromagnetic proof mass damper.

Fig. 1 : scheme of the finite element with ACLD

Fig. 2 : demonstrator

Fig. 3: flexible link with dynamic damper at the free end

Fig. 4 dynamic damper configuration

Fig. 5: dynamic characterization of the flexible link

  1. DIA-RO3 Coordinator Prof. Antonio Tornambè

    The research activities of the Unit Roma Tre have been focused on the realization of a 3D graphical simulator, to be used as an aid to the operator for the remote control of a telemanipulator: the simulator thus realized, although it is at a beta release stage, utilizes the sensors data obtained from the robot encoder, the data obtained by computer simulations of an accurate model of the robot, and the data that can be obtained by analyzing the images of the working space captured by a webcam. The Internet network has been used for the data transmission.