Development of non-constrained master arm with tactile feedback device

In this paper, we consider wireless telerobotic systems and protocol development for low-delay wireless communication. Telerobotics can be defined as the control of robot arms from a remote location. In a telerobotic system, there is a robot arm to be controlled that is identified as the `slave arm', and a remote operator at a distant location using a robotic manipulator that is called the `master arm'. In the control system measurements, actuator delays do degrade the system's performance. Therefore, communication delays between the master and slave arms, and their minimization, are of extreme importance in telerobotics. In this paper, we first develop a new wireless communication protocol, the lightweight wireless protocol (LWP), designed on top of the 802.11 media access control layer. This low-delay wireless LWP protocol is implemented on an embedded system (AirDrop-LWP) without an operating system and its associated overhead. Finally, 2 AirDrop-LWP--embedded systems running this low-delay wireless LWP protocol are used to build a telerobotic system with a Mitsubishi RV-2AJ industrial robot. The LWP protocol is also tested on a robot car controlled by an AirDrop-LWP card as a slave arm and a standard PC as a master arm. The key features of the LWP are a reduced packet size, simple protocol stack, predictive compression of operator movements, and prediction of lost data packets. The LWP protocol is compared with the user datagram protocol and significant performance improvements are observed: a reduced delay of up to 50% and an additional 20% lower delay via compression. Variation in the packet delay times is also an important parameter for the wireless control system. As the standard deviation of the packet delay times increase, and becomes less and less predictable, the resulting telerobotic system will be more and more difficult to operate. We measured the standard deviation of packet delays and observed that it increases with the packet size, and this increase is faster than the increase in mean packet delay.

Nowadays Industrial robots of different kinematic structures and functionality are widely used nowadays in different areas of industry and most of them function autonomously with preprogrammed set of actions or typical trajectories. Some special purposes mobile and stationary robots are human-controlled and in most cases require qualified operator skills. For example, in nuclear industry the mechanical and electro-mechanical “master arm – slave arm” manipulators are widely used. Modern approaches of control systems and human machine interfaces designs allow to eliminate direct copy of kinematic configuration of manipulator arms, add semi-automatic and automated control modes. Key feature of such manipulator systems is a presence of human in control loop, by reason of variety and complexity of manipulations and, in some cases, non-deterministic environment. Due to these factors, it is very desirable to form operator sustainable skills to control such manipulators, including learning process using training systems. This article describes general approaches and practical aspects of the operator training and qualification system for arm-based special purpose manipulators. The set of training system functions include: general manipulator control (basic motion) and grasping actions, manipulator operations in restricted working areas, operator actions using virtual reality helms and multi-monitor visualization, etc. The hardware and software architecture of training system should allow effective training process and teamwork of trainee and instructor to reach good results. The paper proposes ROS-based software part of training system with description of inter-process communication messages, data formats, integration with database and following analysis of trainee action.

The servicing aid tool (SAT) is a teleoperated manipulation system designed for use on the NSTS Orbiter. The system will assist EVA servicing of spacecraft such as the Hubble Space Telescope and Explorer platform. SAT components are spaceflight adaptations of existing ground-based designs from Robotics Research and Schilling Development. Fairchild Space is providing the control electronics, safety system, and flight integration. The manipulator consists of a 6-DOF slave arm mounted on a 1-DOF positioning link in the payload bay. The slave arm is controlled via a highly similar, 6-DOF, force-reflecting master arm. Each slave arm joint receives position commands from the corresponding master arm joint; torque commands are reflected to each master joint based on the current state of the slave joint and the master/slave relationship. Scaled and indexed control will be accommodated, as will various features to ensure safe operation. The paper focuses on the development of the safety system, and operations for the demonstration and servicing missions.

Minimally invasive surgery (MIS) which thinks a great deal of patient’s quality of life (QOL) has attracted attention during about ten years. In this paper, it aims at development of the technology for transmitting force sensation required in medical treatment especially through surgical instruments, such as forceps. In bilateral control, it is a problem how master and slave robots realize the law of action and reaction to the environment. Mechanism of contact with environment and bilateral controller based on stiffness are shown. Master arm in contact with human and slave arm in contact with environment are given compliance, and stable contact with environment can be realized. The proposed method is applied to 3-link master-slave manipulators. As a result, transmission and reproduction of force sensation can be realized. The experimental results show viability of the proposed method.

A single-master, multiple-slave manipulator system and its task-oriented control using VIM (virtual internal model) are proposed. By using this system, the operator no longer has to consider how to control the slave arms in coordination, so the operator can concentrate on his/her task during the operation. An experimental single-master, multislave manipulator system with two slave arms, each of which has six degrees of freedom, is described, and the concept of the system is illustrated. The experimental system does not have a bilateral function, and a master arm can specify the task-oriented variable up to six degrees of freedom. The use of bilateral feedback as well as task-oriented functions will enable the system to deal with more complex tasks. >

Advances in technology have expanded the use of soft actuators in various fields especially in robotics, rehabilitation and medical field. Soft actuator development provides many advantages, primarily being simple structures, high power to weight ratio, good compliance, high water resistance and low production cost. However, most soft actuators suffer the problem of being oversized which could potentially hurt users as it is often made of hard materials such as steels and hard rigid plastics. Current drawbacks of soft actuator implementation in robotic arms are on its excessive weights, causing these robots to be difficult to set up by patients themselves which in turn makes it less applicable for home rehabilitation training program. Hence, there is a need to design a soft actuator which is safe and more flexible, especially for applications in areas of patients in rehabilitation area or in-house rehabilitation program. In this paper, we propose the design of robot arm using master device pneumatic actuator and analyse the implementation for the above purpose. The system comprises primarily of the master and slave arms, two accelerometers and two potentiometers providing references for attitude control, six quasi-servo valves, and SH-7125 microcontroller. Our proposed design exhibits functions of the actuator that has been generated from elastic deformation of extension and contraction of the cylinder structure when high pneumatic pressure is supplied to the chamber. The control performance of the device is investigated using simulation method, whereby the rational model of the robot arm and the quasi servo valve with the embedded controller is implemented and analysed. It is found that the analysed results of the model approved well with the desired values.

This paper presents a novel tongue movement training device using intraoral sensory stimuli from pneumatic balloon actuators placed on an artificial palate.

Design Fundamentals of Master-Slave Systems with a Force-Position Bilateral Control Scheme

Micro manipulator for three dimensional cell cultures such as a cellular aggregate will be presented. We recently reported on a catcher device to manipulate and transport a cellular aggregate in a microwell by using flow control. This paper proposes microfingers to pinch and release a spherical cellular aggregate (φ200 μm). We have studied pneumatic balloon actuator which is featured by its small, soft and safe characteristics suitable for biomedical applications. This paper will present microfingers and their operation, followed by design, fabrication, and characterization. This paper will also show the significance of surface treatment of a fingertip. A series of operations demonstrated on a real cellular aggregate by using newly developed microfingers will be successfully demonstrated.

This paper presents a soft micro-finger composed of a soft micro-actuator and a flexible micro-sensor. Proposed micro-finger is, for the first time, integrated with a pneumatic balloon actuator (PBA) and a strain sensor using liquid metal. Both actuator and sensor can be formed by simple structures with cavities or channels sandwiched by two thin films. The strain sensor is fabricated by filling the space with liquid metal. Proposed design can provide simple batch-fabrication of integrated actuators and sensors for soft micro-fingers. We could succeed in detecting the motion of PBA (560μm×130μm×900μm) by the liquid metal based strain sensor (50μm×50μm×2mm). The gage factor of demonstrated strain sensor is estimated at 0.8. We can say the combination of proposed actuator and sensor is excellent in terms of both fabrication and performance.

Haptics can characterize the complex sense of touch and kinesthetic stimuli through its technology of force or tactile feedback devices. Such technology is developing fast enough to become soon another human-machine interaction similar to computer keyboard or mice. However, currently commercial haptics interfaces are expensive and are typically applied to research projects or expensive systems. Fortunately the trend of the market is forcing haptic developers to release products that can be affordable in a similar fashion as some specialized computer peripherals. Haptics aim is to allow a user to touch, feel, manipulate, create, and/or alter simulated three-dimensional objects in a virtual environment. Most of the applications are dedicated to train physical skills such as medical procedure by using desktop haptic units. These human skills can be captured to model a particular human-behavioural pattern that can be used to build a biometric recognition system. The precision of such systems is reliant on the choice of biometric identifiers. For accurate identity recognition, identifiers must be chosen so that they are unique for each individual. Conventional choices of biometric identifiers include writing style, hand geometry, as well as iris, facial, and fingerprint features. In this paper, we are interested in identity recognition based on humans' manipulation of haptic devices such as PHANToMtrade. The purpose of our analysis is to evaluate the information content of this data source. Hence, we assess the uniqueness of each biometric identifier. Our analysis shows that the haptic data content of identifiers is more suitable in a verification mode rather than in identification mode

This paper describes the implementation, demonstration and evaluation of a variety of autonomous, vision-guided manipulation capabilities, using a dual-arm Baxter robot. Initially, symmetric coordinated bi-manual manipulation based on kinematic tracking algorithm was implemented on the robot to enable a master-slave manipulation system. We demonstrate the efficacy of this approach with a human-robot collaboration experiment, where a human operator moves the master arm along arbitrary trajectories and the slave arm automatically follows the master arm while maintaining a constant relative pose between the two end-effectors. Next, this concept was extended to perform dual-arm manipulation without human intervention. To this extent, an image-based visual servoing scheme has been developed to control the motion of arms for positioning them at a desired grasp locations. Next we combine this with a dynamic position controller to move the grasped object using both arms in a prescribed trajectory. The presented approach has been validated by performing numerous symmetric and asymmetric bi-manual manipulations at different conditions. Our experiments demonstrated 80% success rate in performing the symmetric dual-arm manipulation tasks; and 73% success rate in performing asymmetric dualarm manipulation tasks.

In this paper we present results of a study where perception of dynamic audiotactile feedback to gesture input was examined. Our main motivation was to investigate how users' active input and different modality conditions effect the perception of the feedback. The experimental prototype in the study was a handheld sensor-actuator device that responds dynamically to user's hand movements creating an impression of a virtual texture. The feedback was designed so that the amplitude and frequency of texture were proportional to the overall angular velocity of the device. We used four different textures with different velocity responses. The feedback was presented to the user by the tactile actuator in the device, by audio through headphones, or by both. During the experiments, textures were switched in random intervals and the task of the user was to detect the changes while moving the device freely. The performances of the users with audio or audiotactile feedback were quite equal while tactile feedback alone yielded poorer performance. The texture design didn't influence the movement velocity or periodicity but tactile feedback induced most and audio feedback the least energetic motion. In addition, significantly better performance was achieved with slower motion. We also found that significant learning happened over time; detection accuracy increased significantly during and between the experiments. The masking noise used in tactile modality condition did not significantly influence the detection accuracy when compared to acoustic blocking but it increased the average detection time.

For pt. 1 see ibid., p.526-9 (1996). This paper describes the initial performance evaluation of a tactile feedback actuator introduced in pt. 1. An adaptive PI algorithm using continuously variable gain scheduling helps to compensate for nonlinearities in the solenoid actuator. The closed-loop behavior meets performance specifications, but the mass added to the force-reflecting haptic interface degrades its performance. Improvements in future prototypes may reduce the mass added by the tactile feedback hardware by over 30%. The work concludes with recommendations for psychophysical research that will increase understanding of human performance in tasks using haptic feedback devices.

REVEL is an augmented reality (AR) tactile technology that allows for change to the tactile feeling of real objects by augmenting them with virtual tactile textures using a device worn by the user. Unlike previous attempts to enhance AR environments with haptics, we neither physically actuate objects or use any force- or tactile-feedback devices, nor require users to wear tactile gloves or other apparatus on their hands. Instead, we employ the principle of reverse electrovibration where we inject a weak electrical signal anywhere on the user body creating an oscillating electrical field around the user's fingers. When sliding his or her fingers on a surface of the object, the user perceives highly distinctive tactile textures augmenting the physical object. By tracking the objects and location of the touch, we associate dynamic tactile sensations to the interaction context. REVEL is built upon our previous work on designing electrovibration-based tactile feedback for touch surfaces [Bau, et al. 2010]. In this paper we expand tactile interfaces based on electrovibration beyond touch surfaces and bring them into the real world. We demonstrate a broad range of application scenarios where our technology can be used to enhance AR interaction with dynamic and unobtrusive tactile feedback.