Folding Assembly by Means of Dual-Arm Robotic Manipulation

In this paper, we consider folding assembly as an assembly primitive suitable for dual-arm robotic assembly, that can be integrated in a higher level assembly strategy. The system composed by two pieces in contact is modelled as an articulated object, connected by a prismatic-revolute joint. Different grasping scenarios were considered in order to model the system, and a simple controller based on feedback linearisation is proposed, using force torque measurements to compute the contact point kinematics. The folding assembly controller has been experimentally tested with two sample parts, in order to showcase folding assembly as a viable assembly primitive.Comment: 7 pages, accepted for ICRA 201

Sensorized Tools for Haptic Force Feedback in Computer Assisted Surgery

Structural engineerin

Minimally invasive robotic surgery: force and torque analysis

La cirugía mínimamente invasiva y la incorporación de la robótica en este tipo de procedimientos representa grandes ventajas para el paciente, el cirujano y los sistemas de salud. Sin embargo, los dispositivos comerciales disponibles en la actualidad no cuentan con realimentación de fuerza y tacto, que faciliten al cirujano la identificación de los tejidos y consecuentemente, la reducción de errores en los procedimientos quirúrgicos; por lo cual, el desarrollo de sistemas que cuenten con este tipo de realimentación se convierte en un tema de interés a nivel mundial. El presente artículo contiene una revisión del estado de la técnica con respecto a los sistemas comerciales y experimentales desarrollados en esta área. También, se presentan algunos sensores y modelos matemáticos utilizados para calcular las fuerzas y torques en cirugía mínimamente invasiva.Minimally Invasive Surgery and the adaptation of robotics to these procedures represent many advantages for the patient, the surgeon, and the health program. However, commercial devices used nowadays lack haptic feedback. This fact makes the tissue identification more difficult and increments the injuries risk during the surgical procedure. The development of systems with this kind of feedback has become a topic of interest throughout the world. The present article contains a revision of the state of the art about commercial and experimental systems developed in this area. Models for the force and torque propagation, used in Minimally Invasive Surgery, are also presented

Investigation On Force Scaling For Multi Degree Of Freedom Bilateral Teleoperation Control System

A bilateral control system consists of two actuation systems which are separate but sends and receives information to and from each other. Information shared consists of calculated force and position readings from sensors which feed into the control system. When the actuation systems are in the form of robot manipulators, there are at least two degrees of freedom with each degree of freedom has its own force and position values. When these two systems operate simultaneously, a change in force and position for one system triggers the other to coordinate and attempt to maintain the same values of force and position at both sides and this is termed as a master-slave system. In most cases, both systems are identical and the amount of force and position desired is similar. In some real-life applications, the desired amount of force/position is scaled; i.e. smaller or larger force is desired at one end of the system (master/slave). For this purpose, this research proposes a method to scale the force at either master or slave side by using elements of the mass/inertia matrix of the robot manipulator. Four different scaling values were demonstrated in the experiments to show the validity of the proposed method. Results indicate that the method is viable as the forces were scaled correctly as desired

Neuromorphic vibrotactile stimulation of fingertips for encoding object stiffness in telepresence sensory substitution and augmentation applications

We present a tactile telepresence system for real-time transmission of information about object stiffness to the human fingertips. Experimental tests were performed across two laboratories (Italy and Ireland). In the Italian laboratory, a mechatronic sensing platform indented different rubber samples. Information about rubber stiffness was converted into on-off events using a neuronal spiking model and sent to a vibrotactile glove in the Irish laboratory. Participants discriminated the variation of the stiffness of stimuli according to a two-alternative forced choice protocol. Stiffness discrimination was based on the variation of the temporal pattern of spikes generated during the indentation of the rubber samples. The results suggest that vibrotactile stimulation can effectively simulate surface stiffness when using neuronal spiking models to trigger vibrations in the haptic interface. Specifically, fractional variations of stiffness down to 0.67 were significantly discriminated with the developed neuromorphic haptic interface. This is a performance comparable, though slightly worse, to the threshold obtained in a benchmark experiment evaluating the same set of stimuli naturally with the own hand. Our paper presents a bioinspired method for delivering sensory feedback about object properties to human skin based on contingency-mimetic neuronal models, and can be useful for the design of high performance haptic devices

Force Control of a Unilateral Master-Slave System Using a SCARA Robot Arm

Industrial manipulators have several applications in a multitude of disciplines. The use of industrial manipulators has increased rapidly, and they are more refined in many applications due to advances such as fast response time, high precision, quick speed and a high level of performance. Most industrial manipulators are position-controlled; usually vision and force sensors are not integrated in most commercial industrial robots. Therefore, the addition of force and vision sensing mechanisms is required to successfully automate advanced tasks, and to enable robots to avoid high contact forces while working in applications that require contact with environments. The objective of this thesis is to implement a unilateral master-slave system for medical applications. In this thesis, a Polaris Vicra® optical tracking device is used to represent the master system, while a four degree of freedom (DOF) position-controlled SCARA manipulator from Epson is used to represent the slave system. The manipulator is equipped with a force-torque sensor to facilitate operation in unknown environments. In addition, MapleSim is used to find the dynamic model for the SCARA manipulator. Furthermore, MapleSim is also used to validate the control algorithm prior to implementation on the hardware. Three force control techniques are used in this research and the robot's performance are evaluated. The control techniques are impedance control, admittance control and fuzzy logic control. The admittance and fuzzy logic controllers are applied to the proposed master-slave system while the impedance control is applied to the manipulator model, which was obtained from MapleSim. In order to validate the presented control algorithms, several experiments and simulations were carried out. The experimental results show the ability of the presented controllers (admittance and fuzzy logic) to track the operator signal while keeping the force within the desired range. The simulation and animation of the impedance controller on the other hand, shows that the robot's performance can be evaluated through software

A Force Reflective Master-Slave System for Minimally Invasive Surgery

Minimally invasive surgery involves inserting special instruments into the body cavity through tiny incisions in order to perform surgical procedures. In this paper, the design of a robotic masterslave system for use in minimally invasive surgery is discussed. This system is capable of providing haptic feedback to the surgeon in all available degrees of freedom. System design as well as master and slave bilateral control and communication issues are discussed

Haptics Rendering and Applications

There has been significant progress in haptic technologies but the incorporation of haptics into virtual environments is still in its infancy. A wide range of the new society's human activities including communication, education, art, entertainment, commerce and science would forever change if we learned how to capture, manipulate and reproduce haptic sensory stimuli that are nearly indistinguishable from reality. For the field to move forward, many commercial and technological barriers need to be overcome. By rendering how objects feel through haptic technology, we communicate information that might reflect a desire to speak a physically- based language that has never been explored before. Due to constant improvement in haptics technology and increasing levels of research into and development of haptics-related algorithms, protocols and devices, there is a belief that haptics technology has a promising future