Gianni Castelli

A Fairly General Algorithm to Evaluate Workspace Characteristics of Serial and Parallel Manipulators

Abstract In this paper a fairly general algorithm is proposed for the determination and evaluation of the workspace both for serial and for parallel manipulators. The procedure is based on a binary representation of the workspace and presents the possibility for a general evaluation of the shape and volume for robot workspace characteristics. Two examples are presented to show the practical feasibility of the proposed procedure and its practical results.

A Cable-Based System for Aiding Elderly People in Sit-to-Stand Transfer #

Abstract In this paper a 4-4 cable-based system is presented for an application of aiding elderly people or patients with disabilities at lower limbs, in standing up and sitting operations. Cable-based manipulators have very good kinematic and dynamic characteristics, and they also show other properties such as good transportability and low-cost construction, which make them also suitable for medical applications and rehabilitation. The proposed application is analyzed through a kinetostatic analysis and simulation of the manipulator. An experimental validation of the proposed application is presented by means of an existent prototype, which is called CALOWI (CAssino LOw-cost WIre robot) that is available at LARM in Cassino. A low-cost system for tension monitoring has been used to monitor the forces in the cables during the experimental tests.

A Procedure for the Design of Novel Assisting Devices for the Sit-to-Stand

The Sit-to-Stand (STS) is an activity most people perform numerous times daily. Standing up deals with the transition from two stabilized postures, namely seated to standing, with movement of all body segments except the feet. During the STS the body’s Center of Gravity (COG) is moved upward from a sitting position to a standing position without losing balance and requiring a good coordination of many muscles. Three main phases of the STS movement can be recognized. One begins to stand up by inclining the upper body forward, which moves body mass toward the feet in order to maintain balance after lift-off. Prior to leaving the chair, hip and knee extensor muscles are activated to provide antigravity support for these joints, this action is commonly referred to as “weight shift”. Finally, after leaving the chair, the leg and trunk joints are straightened to achieve upright stance. The STS task can be considered of major importance for impaired and elderly people to achieve minimal mobility and independence. In this paper we detail a procedure for the design of assisting devices to be used for the STS. In par-ticular, an experimental procedure is described firstly to track and record point trajectories and the orientation of the trunk during the STS. This analysis is then used to get information for the design of assisting devices. A proposal and simulation results are presented for a novel mechatronic system. In particular, for the case under study experimental tests are used to drive the actuation system for the reported simulation. A functional mechatronic scheme is then proposed to control the device during its operation.

A Study on the Effects of Cable Mass and Elasticity in Cable-Based Parallel Manipulators

This paper presents numerical and experimental results for an analysis of the effects of cable’s mass and elasticity in cable-based parallel manipulators. It will be shown, through numerical simulation and experimental results, that effects of these characteristics cannot be always neglected, because they affect the pose capability of the end-effector. A planar 2 cable point-mass manipulator is considered as a case of study. The model and results can be further extended to all classes of cable-based manipulators, such as under or fully constrained types.

Experimental Results of a 3-DOF Parallel Manipulator as an Earthquake Motion Simulator

Parallel manipulators are increasingly used in new applications by exploiting their better characteristics with respect to those of serial manipulators, such as higher stiffness, velocity and acceleration, payload. In this paper, experimental results are presented of a novel application of a 3-DOF CaPaMan (Cassino Parallel Manipulator) prototype to simulate point seismograms and 3D earthquake motion. The rigid body acceleration (linear acceleration, angular velocity and acceleration) has been experimentally analyzed to simulate real 3D earthquakes by using the parallel manipulator. Furthermore, first experimental results are reported to analyze earthquake effects on scaled civil structures.Copyright

Analysis and simulation of a new Cartesian cable-suspended robot

Abstract In this article, a manipulator is presented belonging to the class of cable-suspended robots, for which the cable length variations are related by suitable functions in order to achieve specific kinematic characteristics. In particular, in this article, a Cartesian cable-suspended robot is proposed that has eight cables to have three degrees of freedom (DOF) in Cartesian space. The eight cables of the robot are arranged in parallel by pairs with identical length, with the aim of constraining the moving platform to keep a constant orientation with respect to the fixed frame. The robot can be used for selective compliant assembly robot arm (SCARA) motions (when an additional revolute actuated joint is placed on the moving platform) for a variety of applications in which a large workspace is required. In this article, a geometry analysis of the robot is presented together with a numerical simulation of the kinetostatics and dynamics to investigate the robots performances in several operative conditions. Furthermore, a characterization of the position workspace regions is reported for this cable-suspended robot.

Modelling, simulation and testing of a reconfigurable cable-based parallel manipulator as motion aiding system

This paper presents results on the modelling, simulation and experimental tests of a cable-based parallel manipulator to be used as an aiding or guiding system for people with motion disabilities. There is a high level of motivation for people with a motion disability or the elderly to perform basic daily-living activities independently. Therefore, it is of great interest to design and implement safe and reliable motion assisting and guiding devices that are able to help end-users. In general, a robot for a medical application should be able to interact with a patient in safety conditions, i.e. it must not damage people or surroundings; it must be designed to guarantee high accuracy and low acceleration during the operation. Furthermore, it should not be too bulky and it should exert limited wrenches after close interaction with people. It can be advisable to have a portable system which can be easily brought into and assembled in a hospital or a domestic environment. Cable-based robotic structures can fulfil those requirements because of their main characteristics that make them light and intrinsically safe. In this paper, a reconfigurable four-cable-based parallel manipulator has been proposed as a motion assisting and guiding device to help people to accomplish a number of tasks, such as an aiding or guiding system to move the upper and lower limbs or the whole body. Modelling and simulation are presented in the ADAMS environment. Moreover, experimental tests are reported as based on an available laboratory prototype.

Modelling and Simulation of a Cable-Based Parallel Manipulator as an Assisting Device

This paper presents an investigation on a robotic system as assisting device for elderly or people with motion disabilities. There is a high level of motivation for elderly (or disabled people) to perform basic daily-living activities independently. Therefore, it is of great interest to design safe and reliable assisting devices that are able to help end-users in daily life activities. Cable-based robots can accomplish the requirements of safety and flexibility because of their main characteristics. A 4-cable based parallel manipulator has been proposed in this paper as an assisting device to help people in the sit to stand transfer. A modelling and simulation in ADAMS environment are presented and discussed for the system operation.

A Procedure for Experimental Evaluation of the Sit-to-Stand for the Design of Assisting Devices

Sit-to-Stand can be considered the most common operation that can be performed in daily life. Standing up is a complex task characterized by the transfer from one stabilized posture to another with movement of all body segments except the feet. The transfer from sitting to standing and back requires both voluntary movement of different body segments that contribute to the change of posture and equilibrium control during an important displacement of the centre of gravity (COG) of the trunk. The trajectory of the COG is characterized by a movement forward and then backward with simultaneous vertical displacement. Consequently, the entire movement requires a strong coordination between posture and movement. In this paper an experimental procedure is described to track and record point trajectories and the orientation of the trunk during the sit-to-stand. This analysis will be used to get information for further design of novel assisting devices. Then, design requirements are given according to the numerical and experimental results.

Design and Simulation of a New Hybrid Mobile Robot for Overpassing Obstacles

In this paper the design and simulation are presented for a 1-DOF leg-wheel walking machine. A dynamic simulation has been proposed for a low-cost robot, which is capable of a straight walking with only one actuator. Suitable simulations have been carried out to verify the operation of the prototype in several environments.