Jorge Pomares

Virtual disassembly of products based on geometric models

This paper describes different aspects of a disassembly system and presents the information model to obtain, on the one hand, the movements necessary for removing a component, and, on the other, a simulation of the disassembly process carried out. The inputs of the disassembly system are the CAD model of the product to be disassembled and the different features of the components stored in a database. Based on such information, an object-oriented model required for developing the disassembly process in a flexible way is generated. Local and global strategies for the removal of one component, using a set of translational movements, are described. Finally, the paper describes a simulation system that allows the verification of the disassembly movements automatically obtained, and simultaneously, to determine the ease of non-destructive disassembly.

Movement-flow-based visual servoing and force control fusion for Manipulation Tasks in unstructured environments

A new approach for fusing visual and force information is shown. First, a new method for tracking trajectories, called movement flow-based visual servoing system, which presents the correct behavior in the image and in the three-dimensional space, is described. The information obtained from this system is fused with that obtained from a force control system in unstructured environments. To do so, a new method of recognizing the contact surface and a system for fusing visual and force information are described. The latter method employs variable weights for each sensor system, depending on a criteria based on the detection of changes in the interaction forces processed by a Kalman filter.

A survey on FPGA-based sensor systems: towards intelligent and reconfigurable low-power sensors for computer vision, control and signal processing.

The current trend in the evolution of sensor systems seeks ways to provide more accuracy and resolution, while at the same time decreasing the size and power consumption. The use of Field Programmable Gate Arrays (FPGAs) provides specific reprogrammable hardware technology that can be properly exploited to obtain a reconfigurable sensor system. This adaptation capability enables the implementation of complex applications using the partial reconfigurability at a very low-power consumption. For highly demanding tasks FPGAs have been favored due to the high efficiency provided by their architectural flexibility (parallelism, on-chip memory, etc.), reconfigurability and superb performance in the development of algorithms. FPGAs have improved the performance of sensor systems and have triggered a clear increase in their use in new fields of application. A new generation of smarter, reconfigurable and lower power consumption sensors is being developed in Spain based on FPGAs. In this paper, a review of these developments is presented, describing as well the FPGA technologies employed by the different research groups and providing an overview of future research within this field.

Flexible multi-sensorial system for automatic disassembly using cooperative robots

Flexible multisensorial systems are a very important issue in the current industry when disassembling and recycling tasks have to be performed. These tasks can be performed by a human operator or by a robot system. In the current paper a robotic system to perform the required tasks is presented. This system takes into consideration the distribution of the necessary tasks to perform the disassembly of a component using several robots in a parallel or in a cooperative way. The algorithm proposed to distribute the task among robots takes into consideration the characteristics of each task and the sequence that needs to be followed to perform the required disassembly of the product. Furthermore, this paper presents a disassembly system based on a sensorized cooperative robots interaction framework for the planning of movements and detections of objects in the disassembly tasks. To determine the sequence of the disassembly of some products, a new strategy to distribute a set of tasks among robots is presented. Subsequently, the visual detection system used for detecting targets and characteristics is described. To carry out this detection process, different well known strategies, such as matching templates, polygonal approach and edge detection, are applied. Finally, a visual-force control system has been implemented in order to track disassembly trajectories. An important aspect of this system is the processing of the sensorial information in order to guarantee coherence. This aspect allows the application of both sensors, visual and force sensors, co-ordinately to disassembly tasks. The proposed system is validated by experiments using several types of components such as the covers of batteries and electronic circuits from toys, and drives and screws from PCs.

Adaptive Visual Servoing by Simultaneous Camera Calibration

Calibration techniques allow the estimation of the intrinsic parameters of a camera. This paper describes an adaptive visual servoing scheme which employs the visual data measured during the task to determine the camera intrinsic parameters. This approach is based on the virtual visual servoing approach. However, in order to increase the robustness of the calibration several aspects have been introduced in this approach with respect to the previous developed virtual visual servoing systems. Furthermore, the system is able to determine the value of the intrinsic parameters when they vary during the task. This approach has been tested using an eye-in-hand robotic system.

Control framework for dexterous manipulation using dynamic visual servoing and tactile sensors’ feedback

Tactile sensors play an important role in robotics manipulation to perform dexterous and complex tasks. This paper presents a novel control framework to perform dexterous manipulation with multi-fingered robotic hands using feedback data from tactile and visual sensors. This control framework permits the definition of new visual controllers which allow the path tracking of the object motion taking into account both the dynamics model of the robot hand and the grasping force of the fingertips under a hybrid control scheme. In addition, the proposed general method employs optimal control to obtain the desired behaviour in the joint space of the fingers based on an indicated cost function which determines how the control effort is distributed over the joints of the robotic hand. Finally, authors show experimental verifications on a real robotic manipulation system for some of the controllers derived from the control framework.

Survey of visual and force/tactile control of robots for physical interaction in Spain.

Sensors provide robotic systems with the information required to perceive the changes that happen in unstructured environments and modify their actions accordingly. The robotic controllers which process and analyze this sensory information are usually based on three types of sensors (visual, force/torque and tactile) which identify the most widespread robotic control strategies: visual servoing control, force control and tactile control. This paper presents a detailed review on the sensor architectures, algorithmic techniques and applications which have been developed by Spanish researchers in order to implement these mono-sensor and multi-sensor controllers which combine several sensors.

A Robust Approach to Control Robot Manipulators by Fusing Visual and Force Information

In this paper, a method to combine visual and force information using the information obtained from the movement flow-based visual servoing system is proposed. This method allows not only to achieve a given desired position but also to specify the trajectory that the robot will follow from its initial position to its final one in the 3D space. This paper also extends the visual servoing system in order to increase the robustness when errors in the camera calibration parameters appear. Experiments using an eye-in-hand robotic system demonstrate the correct behaviour when important errors exist in the camera intrinsic parameters. After the description of this strategy, we then describe its application to an insertion task to be performed by the robotic system in which the joint use of visual and force information is required. To combine both sensorial systems, a position-based impedance-control system is implemented, which modifies the trajectory generated by the visual system depending on the robot’s interaction with its setting. This modification is performed without knowledge of the exact camera calibration parameters. Furthermore, the visual-force approach based on impedance control does not require having previous knowledge about the contact geometry.

Dynamic Visual Servoing With Chaos Control for Redundant Robots

This paper presents a new dynamic visual control system for redundant robots with chaos compensation. In order to implement the visual servoing system, a new architecture is proposed that improves the system maintainability and traceability. Furthermore, high performance is obtained as a result of parallel execution of the different tasks that compose the architecture. The control component of the architecture implements a new visual servoing technique for resolving the redundancy at the acceleration level in order to guarantee the correct motion of both end-effector and joints. The controller generates the required torques for the tracking of image trajectories. However, in order to guarantee the applicability of this technique, a repetitive path tracked by the robot-end must produce a periodic joint motion. A chaos controller is integrated in the visual servoing system and the correct performance is observed in low and high velocities. Furthermore, a method to adjust the chaos controller is proposed and validated using a real three-link robot.

Java software platform for the development of advanced robotic virtual laboratories

This article presents an interactive Java software platform which enables any user to easily create advanced virtual laboratories (VLs) for Robotics. This novel tool provides both support for developing applications with full 3D interactive graphical interface and a complete functional framework for modelling and simulation of arbitrary serial‐link manipulators. In addition, its software architecture contains a high number of functionalities included as high‐level tools, with the advantage of allowing any user to easily develop complex interactive robotic simulations with a minimum of programming. In order to show the features of the platform, the article describes, step‐by‐step, the implementation methodology of a complete VL for Robotics education using the presented approach. Finally, some educational results about the experience of implementing this approach are reported.