Force Sensor Information Research Articles

Method for Bottle Opening with a Dual-Arm Robot.

This paper introduces a novel approach to robotic assistance in bottle opening using the dual-arm robot TIAGo++. The solution enhances accessibility by addressing the needs of individuals with injuries or disabilities who may require help with common manipulation tasks. The aim of this paper is to propose a method involving vision, manipulation, and learning techniques to effectively address the task of bottle opening. The process begins with the acquisition of bottle and cap positions using an RGB-D camera and computer vision. Subsequently, the robot picks the bottle with one gripper and grips the cap with the other, each by planning safe trajectories. Then, the opening procedure is executed via a position and force control scheme that ensures both grippers follow the unscrewing path defined by the cap thread. Within the control loop, force sensor information is employed to control the vertical axis movements, while gripper rotation control is achieved through a Deep Reinforcement Learning (DRL) algorithm trained to determine the optimal angle increments for rotation. The results demonstrate the successful training of the learning agent. The experiments confirm the effectiveness of the proposed method in bottle opening with the TIAGo++ robot, showcasing the practical viability of the approach.

Robot Precision Assembly Combining With Passive and Active Compliant Motions

Precision assembly is one of the primary goals of robots in manufacturing. Assembly strategies combining active and passive compliant control are presented herein. In this article, we construct a high-dimensional configuration space of robot assembly and then divide the configuration space to its subspaces. We further map the active compliant motion and the passive compliant motion of the manipulator into different subspaces. In one subspace, we construct the constraint function and design the passive compliant motion of the manipulator in the constraint region, where the uncertainties of the system should be eliminated by the environment constraints. In another subspace, we design a force controller based on the low-resolution force sensory information to control the position of the robot. The proposed method avoids the design of precision mechanism systems and the usage of high-quality sensors. Several experiments pertaining to peg-in-hole insertions are conducted to demonstrate the efficiency of the proposed method.

Impedance estimation for robot contact with uncalibrated environments

This paper examines the problem of online estimation of the environment impedance parameters and position during the contact of a robot with an uncalibrated environment. Position controllers are commonly used for free motion, while force controllers are used for constrained motion of robots. However, it is not trivial to set controller parameters for practical contact tasks with unknown environments. In particular, the environmental position is uncalibrated, and it is impossible to determine the contact position through force sensor information because of the presence of a force measurement threshold. To this end, an estimation algorithm based on L-BFGS is proposed to obtain the environmental impedance parameters and position. The estimated environment position is updated with the impedance parameters, and the impedance parameter estimation is directly related to the penetration position. The penetration position is determined by the real position of manipulators and environment surface position. The estimated environmental parameters are used to modify the position and force switching controller parameters; therefore, the accuracy of these parameters can be evaluated by the performance of the modified controller. Simulations and experiments are successfully conducted and validated with the proposed impedance estimation method. The accuracy and effectiveness of the algorithm is verified through the force and trajectory tracking performance in simulations and experiments.

Friction and noise suppression for force control system based on integration of observer and force sensor information

Measuring and controlling external force from the environment and human beings are essential to realize the future application of the robot systems for medical, nursing, and personal support systems. This paper proposes a friction and noise suppression for force control system based on the integration of the reaction torque observer and force (torque) sensor information. The proposed method performs external force estimation by integrating the low-frequency component information of the force sensor and the high-frequency component of the force information estimated by reaction torque observer (RTOB). By using the low-frequency component of the force sensor, the effect of static friction can be suppressed, and the high-frequency part of RTOB can be used to attenuate the noise component. As a result, the performance of the force control system can be enhanced. The proposed method is evaluated through the experiments of the force control and bilateral control as a position/force hybrid control.

Evaluation of Different Modes of Haptic Guidance for Robotic Surgery

Abstract The evolution of surgery has resulted in a plethora of systems varying in their application field, size, as well as degree of autonomy. Especially systems which combine principles of so-called synergistic robotic systems and master-slave-telemanipulators are interesting concerning cooperative aspects of surgeon and robotic system. While the former provide haptic guidance information (“virtual fixtures”), the latter provide haptic feedback from position or force sensor information of the slave device. During the design of these combined systems particular attention has to be paid during the allocation of information to the haptic information channel as superimposing of haptic guidance information and haptic sensor feedback can lead to concealment of essential feedback information. This paper reports on an experimental usability evaluation of different haptic guidance modes varying in their degree of autonomy as well as degree of freedom (DOF) with respect to three surgical scenarios, namely reaching a predefined position and orientation, tracking a predefined 3D trajectory, and applying a defined force (such as during e.g. a 3D-bone milling task). The goal was to evaluate whether some DOF of haptic guidance information can be left free for force sensor information feedback. General findings indicate that haptic guidance does not have to be augmented on three DOF to improve usability. Therefore, a combination of haptic sensor information feedback and haptic guidance information divided between individual DOF seems to be a potential solution.

The Study about Estimating a Form of Needle by Using a Force Sensor Information for Puncture Robot

The Study about Estimating a Form of Needle by Using a Force Sensor Information for Puncture Robot

Flexible robotic grasping strategy with constrained region in environment

Grasping is a significant yet challenging task for the robots. In this paper, the grasping problem for a class of dexterous robotic hands is investigated based on the novel concept of constrained region in environment, which is inspired by the grasping operations of the human beings. More precisely, constrained region in environment is formed by the environment, which integrates a bio-inspired co-sensing framework. By utilizing the concept of constrained region in environment, the grasping by robots can be effectively accomplished with relatively low-precision sensors. For the grasping of dexterous robotic hands, the attractive region in environment is first established by model primitives in the configuration space to generate offline grasping planning. Then, online dynamic adjustment is implemented by integrating the visual sensory and force sensory information, such that the uncertainty can be further eliminated and certain compliance can be obtained. In the end, an experimental example of BarrettHand is provided to show the effectiveness of our proposed grasping strategy based on constrained region in environment.

A Force-Sensing System on Legs for Biomimetic Hexapod Robots Interacting with Unstructured Terrain.

The tiger beetle can maintain its stability by controlling the interaction force between its legs and an unstructured terrain while it runs. The biomimetic hexapod robot mimics a tiger beetle, and a comprehensive force sensing system combined with certain algorithms can provide force information that can help the robot understand the unstructured terrain that it interacts with. This study introduces a complicated leg force sensing system for a hexapod robot that is the same for all six legs. First, the layout and configuration of sensing system are designed according to the structure and sizes of legs. Second, the joint toque sensors, 3-DOF foot-end force sensor and force information processing module are designed, and the force sensor performance parameters are tested by simulations and experiments. Moreover, a force sensing system is implemented within the robot control architecture. Finally, the experimental evaluation of the leg force sensor system on the hexapod robot is discussed and the performance of the leg force sensor system is verified.

Micro-vision servo control of a multi-axis alignment system for optical fiber assembly

This paper describes a novel optical fiber assembly system featuring a multi-axis alignment function based on micro-vision feedback control. It consists of an active parallel alignment mechanism, a passive compensation mechanism, a micro-gripper and a micro-vision servo control system. The active parallel alignment part is a parallelogram-based design with remote-center-of-motion (RCM) function to achieve precise rotation without fatal lateral motion. The passive mechanism, with five degrees of freedom (5-DOF), is used to implement passive compensation for multi-axis errors. A specially designed 1-DOF micro-gripper mounted onto the active parallel alignment platform is adopted to grasp and rotate the optical fiber. A micro-vision system equipped with two charge-coupled device (CCD) cameras is introduced to observe the small field of view and obtain multi-axis errors for servo feedback control. The two CCD cameras are installed in an orthogonal arrangement—thus the errors can be easily measured via the captured images. Meanwhile, a series of tracking and measurement algorithms based on specific features of the target objects are developed. Details of the force and displacement sensor information acquisition in the assembly experiment are also provided. An experiment demonstrates the validity of the proposed visual algorithm by achieving the task of eliminating errors and inserting an optical fiber to the U-groove accurately.

Unscented Kalman Filter for Real-Time Load Swing Estimation of Container Cranes Using Rope Forces

The container crane represents the link between the containership and the port. It dictates the general conditions for the efficiency of container handling from the ship to the land and vice versa. While containers are handled by the crane, load swing reduces the rate of container turnover. In order to reduce load swing control systems are employed. Closed-loop control systems contain devices to track the position of the load with respect to the trolley's position. Accurate tracking of the load's motion during operation requires additionally installed sensors. Alternatively, the principle of state estimation can be employed. The observation of the motion of the container is carried out by a system model in parallel to the real system, taking into account the available rope force sensor information. Both, nonlinear system model and nonlinear sensor model are taken into consideration. An unscented Kalman filter is designed to estimate the states of the motion of the load. The observer is validated at the container crane test stand in order to provide accurate states for load swing control. Results are presented and discussed.

Research of Force Sensor-based Control on Flight Simulator Motion Platform

Six degrees of freedom (6-DOF) motion platform provides the sense of motion for pilot when the flight simulator is operating. This paper presents a new method of tracking acceleration instead of tracking displacement, while the latter has been widely used. Since the acceleration sensor poor low-frequency characteristics, a new motion platform control method based on force sensor is proposed. By means of the derivation of the dynamics equation, platform acceleration can be obtained indirectly from the force sensor information. Taking RTO (Rejected Takeoff) as an example, in which the washout filter algorithm is designed to access the parameters such as expected acceleration of the motion platform. In addition, a motion platform acceleration controller based on inverse dynamics feedforward control scheme is designed and compared to displacement tracking. Simulation results show that: using the force sensor can achieve the acceleration of the motion platform tracking control, and compared with the conventional displacement control, the acceleration tracking control can significantly improve the tracking accuracy.

Prototyping a Hybrid Cooperative and Tele-robotic Surgical System for Retinal Microsurgery

This paper presents the design of a tele-robotic microsurgical platform designed for development of cooperative and tele-operative control schemes, sensor based smart instruments, user interfaces and new surgical techniques with eye surgery as the driving application. The system is built using the distributed component-based cisst libraries and the Surgical Assistant Workstation framework. It includes a cooperatively controlled EyeRobot2, a da Vinci Master manipulator, and a remote stereo visualization system. We use constrained optimization based virtual fixture control to provide Virtual Remote-Center-of-Motion (vRCM) and haptic feedback. Such system can be used in a hybrid setup, combining local cooperative control with remote tele-operation, where an experienced surgeon can provide hand-over-hand tutoring to a novice user. In another scheme, the system can provide haptic feedback based on virtual fixtures constructed from real-time force and proximity sensor information.

1A1-O09 教示データからの特徴空間の構成にもとづく力覚情報を用いた抱え上げ行動の生成(進化・学習とロボティクス)

This paper presents a learning approach to acquire holding-up manipulation by a humanoid robot. Information of force sensors attached at the surface of the arms are mapped to a lower-dimensional space and utilized to find a better configuration for the manipulation task. The proposed motion generation framework was verified by simulations with a humanoid robot. It was shown that the robot could judge failure of its manipulation using force sensor information, and succeed to modify its configuration so as to realize holding-up manipulation.

A cooperative robotic system based on multiple sensors to construct metallic structures

This paper describes a multisensorial robotic system to automatically construct metallic structures. Two robots must work cooperatively in the same workspace to perform the task. The robots are automatically guided using visual and force sensor information. A new time-independent visual force control system which guarantees the adequate robot behaviour during the construction of the structure is described. During the construction of the structure, a human operator works cooperatively with the robots in order to perform some tasks which cannot be automatically developed by the robots. To do so, a new human–robot cooperation approach is described in order to guarantee the human safety. The correct behaviour of the different subsystems proposed in the paper is demonstrated in Section 6 by the construction of a real structure composed of several metallic tubes and different types of pieces to join them.

Proposal of ZMP Estimation Methods with Torque Information Estimated from Current Measurement and Its Application

In this paper, several models of approximating ZMP for humanoid are proposed without force sensors. Generally, ZMP is determined by using force sensor information. In this paper, this torque information is estimated by measuring motor-driving current. This paper discusses several estimation models whose results are compared by experiments. Furthermore, we examined effectiveness of proposed models. The results show that the proposed estimation methods are effective in semi-static condition. Specially, these proposed methods have advantages when a humanoid without a force sensor is controlled under change of gravity direction such as a slope condition.

Measurement of force sensory information in ultraprecision assembly tasks

Automation of assembly tasks has previously been tackled by many researchers. They mostly focused on the geometric constraints related to a considered task, e.g., relative configuration change between the peg and the hole. Such an approach, however, has a limited validity in the sense that, unlike ultraprecision assembly studied in the present study, it assumes that the dimensional tolerance is fairly large so that it allows change to the relative configuration of the two mating parts in an obvious fashion. The paper investigates what makes highly precise assembly tasks very difficult from the viewpoint of automation of the tasks. Tolerance considered in the present study is in the range of 3-9 /spl mu/m. We focus on force sensory information involved in a high-precision peg-in-a-hole task of a polygon mirror unit because a position-based analysis under such a narrow dimensional tolerance seems inappropriate. A variety of insertion experiments are conducted by skilled and unskilled subjects for comparison purposes in which associated force signals are measured and analyzed.

Hybrid Control of a DD Robot Using an Online Visual and Force Sensor Fusion Method.

In this paper a force and vision sensor fusion method is proposed in order to extend the conventional force and position hybrid control. The purpose of this system is to apply a controlled normal force on a surface with unknown shape. We achieve our objectives by using a partially reconstructed trajectory, visualized by one CCD camera installed on the end-effector, and complementing it with the tactile information provided by a force sensor. Based on the force sensor information, the normal and tangential directions of the constraint surface are identified and the desired point, obtained from the CCD camera, is projected back to this surface. The only assumption done here is that the surface is smooth enough to allow us to do a good estimation of the constraint surface. This method was developed in order to simplify the use of the 6-DOF direct-drive (DD) robot proposed by Utsumi and Todo, which was initially designed to do polishing tasks. The referred DD robot was designed with a particular structure in order to lower its whole weight : a 3-DOF parallel link arm robot and a 3-DOF orientation table. By using this system, the user can easily draw an arbitrary path on the surface of the object before he fixes it on the orientation table, without thinking about complicated curved path and surface equations or coordinate system transformations.

3915 視覚と力覚の融合によるロボットのオンライン目標軌道生成法

In this paper the concept of force and position hybrid control proposed by Raibert et al. is adapted in order to incorporate a changeable constraint coordinate frame, on which the controller is implemented. An online method for generating this constraint frame based on visual and force sensor data fusion is proposed. The basic idea here is to complement a partially reconstructed trajectory (a 2D information) drawn on the object surface (with unknown shape), visualized by one CCD camera installed on the end-effector, with the tactile information provided by a force sensor installed on the same end-effector. This is achieved by identifying the normal and tangential directions of the constraint surface based on the force sensor information, then estimating the constraint surface for the next desired point and finally projecting back on this surface the desired point based on the 2D image grabbed from the CCD camera. This method is experimentally verified using a 6-DOF direct-drive (DD) robot.

Coordinative Control of Different Kind of Manipulators Using an Incremental Fuzzy Compensator

A coordinative motion control is described for two different kind of manipulators by using a master-slave concept. Here, the master part consists of a pantagraph-type two link manipulator driven by a torque command, whereas the slave part is an industrial manipulator driven by a position command with a force torque sensor. To achieve a desired contact force between the slave manipulator and an object, a compensative position command is generated by using an incremental fuzzy reasoning with the force sensor information. The effectiveness is verified by experiments.

Telerobotic Master Reflected Force Adjustment with Local Feedback

Efficient telerobotic operation requires an intuitive transmission of forces and velocities between the master and slave manipulators. However, due to friction in the joints of each kinematic chain, the associated Cartesian space impedance matrices are not diagonal. The result is a misalignment between the applied force and resulting velocity vectors. While a force sensor on the slave is often used to provide an internal feedback to eliminate the problem for this manipulator, the same is not UBually true for the master. A local feedback of available velocity and force sensory information to the master is proposed which would diagonalize its effective mechanical damping to allow a correct display of force direction information from the slave.