Foto del docente

Vincenzo Parenti Castelli

Emeritus Professor

Alma Mater Studiorum - Università di Bologna


Keywords: prosthesis and orthosis design equivalent mechanisms of human joints compliant mechanisms clearance modelling of kinematic pairs synthesis and analisys of spatial mechanisms biomedical tools and devices for minimally invasive surgery

1 - Advanced methods of analysis and synthesis of open and closed chain spatial mechanisms. In particular: determination of efficient algorithms for real-time control; singularity avoidance; synthesis of new isotropic architectures; definition of kinemati and dynamic performance indeces.

2 - Development of new architectures of compliant mechanisms and of original methods for the modelling and the mechanism real-time control.

3 - Algorithms for the evaluation of the influence of the manipulator joint clearance (open and closed chains).

4 - New equivalent mechanisms for the passive motion simulation of human articulations (specifically knee and ankle), taking into consideration the influence of ligament and bone interactions.

5 - Synthesis and design of advanced prosthetic arms for shoulder and knee amputees (based on patents of the responsible of the research and his collaborators).

6 - Synthesis and design of robotic rehabilitation systems and biomedical devices.

1. Advanced methods of synthesis and analysis of spatial mechanisms.

Special families of parallel manipulators may be conceived that may overcome the typical drawbacks of closed-chain mechanisms (limited dexterity, involved kinematic relations, critical singularities), though preserving their favorable characteristics (large payload to robot weight ratio, stiffness, high dynamic performances). In this perspective, innovative parallel robots for translational motion have been designed. In many instances, they exhibit outstanding performances, such as full decoupling of motion and input-output homokinetic transmission.

2. Compliant mechanisms.

An iterative technique to perform the non-linear position analysis of planar compliant mechanisms has been developed. The technique makes it possible to find the position and orientation (pose) of each link of a mechanism whose input link deflection is assigned. The innovative part is that, instead of relying on the finite-element method, large deflections are considered, and the position analysis is solved without resorting to the linear approximation of small deflections. The technique is highly suitable for rigid-link mechanisms with compliant kinematic pairs. Different types of compliant kinematic pairs have been developed and other types are under investigation in order to define their performances.

3. Joint clearance modelling.

The presence of clearance in a mechanism's kinematic pairs causes additional degrees of freedom and then errors in the pose (position and orientation) of a mechanism's reference link. The aim of this activity is the modelling of planar and spatial clearance-affected kinematic pairs and the development of algorithms which determines the pose error induced by clearance on a mechanism's links.

4. Equivalent spatial mechanisms for the human joint motion simulation.

The objective of this activity is the definition of kinematic and dynamic models of the human knee that can have both theoretical and practical applications. The aim is pursued by a careful analysis of the knee structures which drive and constrain the natural motion of the joint. Starting from studies carried out in collaboration with the Oxford Orthopaedic Institute of the University of Oxford (Great Britain), new results have been obtained in collaboration with the Rizzoli Orthopaedic Institute (Bologna, Italy). These results, presented in several papers in the last few years, proved to be useful for the prosthetic design. New mechanisms are also investigated to reproduce the relative motion of the main bones of the ankle joint during passive motion (equivalent mechanisms). The mathematical models of these new mechanisms represent a powerful tool both for pre-operation planning and for the prosthesis design. The collaboration with the Rizzoli Orthopaedic Institute (Bologna, Italy) makes it possible to collect experimental data in order to define and test the models.

5. Prosthesis design.

Based on the theoretical achievements, internal knee and ankle prosthesis have been designed, also in collaboration with Rizzoli Orthopaedic Institute. Moreover, a further activity, carried out with the INAIL Prosthesis Center (Bologna, Italy), has been focused on the development of a new electrically-powered prosthesis for upper limb amputees with a high level amputation. Both innovative mechanical architectures and control strategies are studied.


6. Synthesis and design of robotic rehabilitation systems and biomedical devices.

The activity focuses on the synthesis of exoskeletons for the rehabilitation of patients suffering from motor disabilities derived from various causes such as stroke. In particular, the synthesis and design of hand and upper limb exoskeletons are addressed. Regarding the design of biomedical devices, the synthesis and design of tools for minimally invasive surgery, such as laparoscopic interventions, are at an advanced stage.