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Workshop II
Parallel and Cable Robots: Learning From Past For Future Frontiers
The Dimensional Synthesis of Cable-Driven Parallel Robots

Prof. Philippe Cardou, Laval University

A hint of the ideas that will be discussed.


One of the key advantages of cable-driven parallel robots (CDPRs) over other types of manipulators is their reconfigurability. The modularity of the winch systems that they rely on and their relatively light weight can allow their rapid deployment and the modification of their geometry. In order to fully take advantage of this characteristic, it would be interesting to provide the CDPR operator with an algorithm that can take as an input the desired workspace and related environmental constraints and return the best corresponding CDPR geometry.

To this end, we first review the mathematical expressions of the wrench-feasible workspace of CDPRs and their collision-free workspace. We then show how these expressions can be included in the standard form of a nonlinear programming problem. Two formulations of such problems will be reviewed: one involving convex relaxations over boxes inside the workspace and the other involving a simpler discretisation thereof. Examples will be provided to illustrate and assess the usefulness of both methods.

Cable Robots Applications in Art: Challenges and Developments

Prof. Hamid D. Taghirad, K. N. Toosi University of Technology


Cable and parallel robotics have been gaining more attention among researchers due to their unique characteristics and applications. Simple structure, high payload capacity, agile movements, and simple structures are the main characteristics that nominate cable-robots from the other types of manipulators for many applications such as imaging, cranes, agriculture, etc. The ARAS Parallel and Cable Robotics (PACR) group is focused on the development of such novel manipulators and their possible applications. Interdisciplinary research fields such as dynamics and kinematic analysis using classic and modern approaches, development of easily deployable robots thorough robust controllers, implementation of novel self-calibration algorithms, and establishing modern and multi-sensor perception systems for them are among the active lines of research in this group. In this workshop a brief overview of these advancement is introduced, and some commercial products through the spin-off and startup companies originated from the team is explained. Kamalolmol® robot is a representative of such products, which is a fast deployable edutainment cable-driven robot for calligraphy and painting (chiaroscuro) applications. The parallelogram structure used in the cable structure of the system, which will significantly increase the speed of this robot will be given more attention.

Relating the Fundamental Research of Cable-Driven Parallel Robots to Practical Developments

Dr. Darwin Lau, The Chinese University of Hong Kong


Cable-driven robots have been studied in recent years due to its unique characteristics and advantages. As a result, they have been used in a wide range of applications from large-scale manipulation, bio-inspired robots to rehabilitation. From modelling, dynamics, control and workspace analysis, there exists many difficult challenges due to the characteristic that cables can only pull and not push. Despite its recent popularity and attractive advantages, the use of cable-driven robots in the real-world is only slowly gaining traction. In this presentation, the relationship between fundamental developments and practical application will be presented. This will include the generalised modelling framework, software development for cable-driven robots, and the development of new control and analysis techniques, and ultimately its usage within applications such as building construction, bio-inspired robots and service maintenance.

Underactuated Cable-Driven Parallel Robots: Theoretical and Practical Challenges

Prof. Marco Carricato, Department of Industrial Engineering, University of Bologna, Italy

Edoardo Idà, Department of Industrial Engineering, University of Bologna, Italy


Cable-Driven Parallel Robots (CDPRs) are parallel robots that use cables in place of rigid extensible legs to move the end-effector (EE). CDPRs present specific advantages over traditional parallel robots, such as remarkably large workspaces. Since guaranteeing positive tensions in cables is a necessary requisite to control the pose of the robot, the unilateral constraints imposed by cables complicate the system control.

CDPRs equipped with a limited number of cables may be favorable to use in several applications, in which the task to be performed requires a limited number of controlled freedoms, or a limitation of mobility is acceptable to enhance accessibility, decrease complexity, and ultimately cost. However, underactuated CDPRs are intrinsically underconstrained, since their EE is subject to fewer constraining actions than the number of EE DoFs. Consequently, the EE preserves some freedoms, and its pose cannot be prescribed entirely. In addition, once the actuators are locked, EE natural oscillations may arise, a condition that is referred to as free motion.

Our speech focuses on the geometrico-static and free motion modeling of underactuated cable- driven parallel robots, and their application to equilibrium identification, stability analysis, trajectory planning, and parameter identification.

Cable-driven Parallel Robots and Industrial Applications

Stéphane Caro, National Centre for Scientific Research (CNRS)


Cable-Driven Parallel Robots (CDPRs) form a particular class of parallel robots whose moving platform is connected to a fixed base frame by cables. The connection points between the cables and the base frame are referred to as exit points. The cables are coiled on motorized winches. Passive pulleys may guide the cables from the winches to the exit points. A central control system coordinates the motors actuating the winches. Thereby, the pose and the motion of the moving platform are controlled by modifying the cable lengths. CDPRs have several advantages such as a relatively low mass of moving parts, a potentially very large workspace due to size scalability, and reconfiguration capabilities. Therefore, they can be used in several applications, e.g. heavy payload handling and airplane painting, cargo handling, warehouse applications, large-scale assembly and handling operations, and fast pickand- place operations. Other possible applications include the broadcasting of sporting events, haptic devices, support structures for giant telescopes, and search and rescue deployable platforms. This keynote will deal with the design, modeling, workspace analysis and control of CDPRs. A focus will be put on the development of CDPRs in Nantes, France, and their potential industrial applications.

Transfer of Cable Robots into Applications for Construction Automation

Prof. Tobias Bruckmann, University of Duisburg-Essen


Construction is a field still dominated by manual work. Several approaches to introduce automated systems have been proposed, and currently numerous initiatives are developing demonstrators and prototypes. However, it is still a challenge for conventional robots to realize construction tasks since – among other issues – the pure volume of a construction project is hard to cover.

Here, Cable-Driven Parallel Robots show relevant advantages. They can realize extremely large workspaces, are configurable and can be erected easily using lightweight modular elements. It is even conceivable to realize CDPR using a climbing frame to address multi-storey buildings. Clearly, these developments are only reasonable if digital building models are available which where became rapidly popular during the last few years in the context of Building Information Modeling (BIM).

The talk addresses ongoing projects at the University of Duisburg-Essen that aim at realizing automated construction using CDPR. Besides virtual models and simulation tools, the realized demonstrators are presented.

More Info: Link1, Link2

Cable-Driven Parallel robots; Control Challenges and Solutions

Dr. Mohammad A. Khosravi, Amirkabir University of Technology


In recent decades, the growing need of industry for high-speed robots with a large workspace has led to the development of cable-driven parallel robots (CDPR). Having significantly lower inertia than the rigid linkage robots makes CDPRs a unique alternative for applications with large workspace requirements and high-speed manipulation demands. However, by cables we may exert only tensile force in pulling direction. The positive tensile force of the cables in CDPRs is guaranteed either through a passive force, such as gravity, or using redundant cables in their structure. This challenge motivates the researchers to develop desirable control algorithms for a CDPR to maintain positive tension in all the cables while having a suitable tracking performance. This talk addresses the control challenges in CDPRs and discusses some approaches that suitably employed for this class of robots. In particular, the first part of the talk demonstrates the CDPRs kinematics and their different types of workspace as well as their dynamics. The second part of the talk focuses on control challenges of the CDPRs and next, some solutions are introduced. At the end, ongoing and future direction in the control of the CDPRs will be discussed.

Automatic tracking of free-flying insects using a cable-driven robot

Dominique Martinez, LORIA, a computer science laboratory in Nancy, France


In this talk, I will describe an application of cable-driven parallel robots (CDPRs) to insect flight research. The flight mechanics of insects and their sensorimotor system have fascinated scientists for a very long time. Yet, studying them experimentally is difficult because of the small size of insects and their high speed of motion. Consequently, previous studies were limited to tethered flights, hovering flights, or restricted flights within confined laboratory chambers. Here, I will report the development of a CDPR, named lab-on-cables, for tracking and interacting with a free-flying insect. In this approach, cameras are mounted on cables, so as to move automatically with the insect. We validated the lab-on-cables with Agrotis ipsilon moths (ca. 2 centimeters long) flying freely up to 3 meters per second. The analysis of flight kinematics is consistent with a helicopter model of insect flight, whereby flight speed is controlled by body pitch via changes in the stroke plane angle.

Workshop II
- Parallel and Cable Robots: Learning From Past For Future Frontiers

Prof. Philippe Cardou, Laval University

Speech Title: "The Dimensional Synthesis of Cable-Driven Parallel Robots"


Bio: Philippe Cardou received the B.Eng. degree in mechanical engineering from Universite Laval, Quebec City, in 2003, and the Ph.D. degree from McGill University, Montreal, in 2008. In 2007, he joined the Department of Mechanical Engineering, Universite Laval, where he currently works as a professor. He specializes in the design of robots and articulated mechanisms, with a strong interest in kinematics and optimisation. In his perpetual quest for “the optimal solution”, he tries to combine the creativity of the designer with the computing power of the machine.

Prof. Hamid D. Taghirad, K. N. Toosi University of Technology

Speech Title: "Cable Robots applications in Art: Challenges and Developments"


Bio: Hamid D. Taghirad has received his B.Sc. degree in mechanical engineering from Sharif University of Technology, Tehran, Iran, in 1989, his M.Sc. in mechanical engineering in 1993, and his Ph.D. in electrical engineering in 1997, both from McGill University, Montreal, Canada. He is currently the University Vice-Chancellor for Global strategies and International Affairs, Professor and the Director of the Advanced Robotics and Automated System (ARAS), Department of Systems and Control, Faculty of Electrical Engineering, K. N. Toosi University of Technology, Tehran, Iran. He is a senior member of IEEE, and Editorial board of International Journal of Robotics: Theory and Application, and International Journal of Advanced Robotic Systems. His research interest is robust and nonlinear control applied to robotic systems. His publications include five books, and more than 250 papers in international Journals and conference proceedings.

Dr. Darwin Lau, The Chinese University of Hong Kong

Speech Title: "Relating the Fundamental Research of Cable-Driven Parallel Robots to Practical Developments"


Bio: Darwin Lau currently works at the Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong. Darwin does research in Robotics Kinematics, Dynamics and Control Systems Engineering of redundantly actuated complex mechanisms, such as anthropomorphic and cable-driven robots. Applications of the work include biomechatronics, and construction and architecture robotics.

Dr. Mohammad A. Khosravi, Amirkabir University of Technology

Speech Title: "Cable-Driven Parallel Robots: Control Challenges and Solutions"


Bio: Dr. Mohammad A. Khosravi has received his M.Sc. and Ph.D. degree both from K. N. Toosi University of Technology, Tehran, Iran, in 2013, respectively, in electrical engineering. He is currently an assistant professor with Amirkabir University of Technology. His research interests lie in the areas of parallel robotics, cable driven robots, robust control and nonlinear control theory.

Prof. Tobias Bruckmann, University of Duisburg-Essen

Speech Title: "Transfer of Cable Robots into Applications for Construction Automation"


Bio: Dr. Tobias Bruckmann received the Dipl.-Ing. in Mechanical Engineering from the University of Duisburg-Essen, Duisburg, Germany, in 2004 and the Dr.-Ing. In 2010. He is currently working as a Lecturer and Research Group Leader at the Chair of Mechatronics, University of Duisburg-Essen, Germany, where he is leading a research team with experiences in numerous fields of robotics, including cable-driven parallel manipulators, construction machines and human-machine interaction. His interests focus on cable-driven parallel manipulators, mechatronic system design and real-time control. Dr. Bruckmann is co-initiator and member of the scientific committee of the “International Conference on Cable-Driven Parallel Robots”, that took place in Stuttgart, Germany, 2012, in Duisburg, Germany, 2014, in Québec, Canada, 2017 and in Krakow, Poland, 2019. In parallel, he was member of the scientific committees of the annual IFToMM D-A-CH Conferences 2015 to 2020.

Prof. ‪Stéphane Caro, National Centre for Scientific Research (CNRS)

Prof. Marco Carricato, Department of Industrial Engineering, University of Bologna, Italy

Speech Title: "Underactuated Cable-Driven Parallel Robots: Theoretical and Practical Challenges"


Bio: Marco Carricato (Senior Member, IEEE) received the M.Sc. degree (Hons.) in mechanical engineering, in 1998, and the Ph.D. degree in mechanics of machines, in 2002. He has been with the University of Bologna, since 2004. He was a Visiting Researcher with the University of Florida, USA; Laval University, Canada; University of Guanajuato, Mexico; Inria Sophia Antipolis, France; Ecole Centrale of Nantes, France; and The Hong Kong University of Science and Technology. He is currently a Full Professor. His research interests include robotic systems, servo-actuated automatic machinery, and the theory of mechanisms. He was awarded the AIMETA Junior Prize 2011 by the Italian Association of Theoretical and Applied Mechanics for Outstanding Results in the field of Mechanics of Machines. He is an Associate Editor of the journal Mechanism and Machine Theory (Based on document published on 5 April 2021).

Edoardo Idà, Department of Industrial Engineering, University of Bologna, Italy

Speech Title: "Underactuated Cable-Driven Parallel Robots: Theoretical and Practical Challenges"


Bio: Edoardo Idà (Member, IEEE) received the M.Sc. degree (Hons.) in Mechanical Engineering from the University of Bologna in 2017, and the Ph.D. degree (Hons.) in Mechanics and Advanced Engineering Sciences, in 2021, from the same institution. He is currently a Post-Doc researcher at the University of Bologna. His research interests include cable-driven robotic systems and continuum parallel robots.

Stéphane Caro, National Centre for Scientific Research (CNRS)

Speech Title: "Cable-Driven Parallel Robots and Industrial Applications"


Bio: Stéphane Caro works as Director of Research at the National Centre for Scientific Research (CNRS). He is the head of the “Robots and Machines for Manufacturing Society and Services” (RoMaS) Team at LS2N. Dr. Caro received his Engineering and M.Sc. degrees in mechanical engineering from Ecole Centrale Nantes in 2001, and his Doctorate degree in from the University of Nantes in 2004. He was a Post-doctoral Fellow in the Centre for Intelligent Machines, McGill University in 2005 and 2006. Dr. Caro’s research focuses on design, modeling and control of cable-driven parallel robots and reconfigurable parallel robots. He is the author of 67 papers published in international journals, 159 papers presented in international conferences, 46 contributions in books and 6 patents.

Dominique Martinez, LORIA, a computer science laboratory in Nancy, France

Speech Title: "Automatic tracking of free-flying insects using a cable-driven robot"


Bio: Dominique Martinez is a CNRS senior scientist (Director of Research) and works at LORIA, a computer science laboratory in Nancy, France. His research is based on an interdisciplinary approach using engineering techniques for system neuroscience and applying neurophysiological principles to technical implementations.

Ryan Caverly, University of Minnesota

Session 2 Chair: " PACR Frontiers"


Bio: Professor Caverly's research interests include the dynamic modeling and control of aerospace, mechanical, and robotics systems. In particular, he is interested in theoretical developments related to input-output stability, as well as optimal and robust control of linear and nonlinear systems. His applied research focuses on accurate, yet computationally-efficient, dynamic modeling of systems with structural flexibility, such as flexible aircraft, spacecraft, and robotic manipulators, as well as the use of new and existing theory to control these systems.

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