Insect Robots Designed

The mobility of animals, including many insects, is typically superior to current legged robots. This fact recommends the use of animal designs in robot. However, the reality of current technology often encourages engineers to use different designs for legged robots than those found in nature. Some robots use mechanisms to couple their joints for the purposes reducing the number of actuators of simplifying the control problem. Actuators are typically heavy and reducing their number can increase the payload or range of a robot.

When early legged robots were developed, computational limitations impeded the use of onboard computers to coordinate many joints. The ASV, Titan IV, and Dino are three of many robots that use pantograph mechanisms to uncouple the vertical and horizontal motions of their feet. Dante II used power screws to achieve large forces with small motors to save weight, but the resulted in slow movements. The K2T carab robot used cables, brakes and clutches to move its 17 joints with just 5 motors. RHEX is a recent robot that adheres to this strategy of simplified mechanical designs. It uses just one motor in each of its six legs to drive each foot in a circular path. It speeds each foot through its swing phase relative to its stance phase so that the robot can walk in insect gaits despite its simple mechanical design. Mechanical coupling and simplicity can ease the development of legged robots. However, the tradeoffs include reduced mobility.

Robot Design Using Dry Adhesives

A climbing robot design, using dry adhesion forces, has to be developed in order to maximize the effectiveness of the attachment system. In particular there are three main requirements for developing such a robot:
1. Maximize the attachment area.
2. Apply preload between vehicle and vertical surface for increasing the attaching force.
3. Use peel force during the detaching phase.

Two different vehicle concepts were developed. The first one is a wheg (wheel-leg) vehicle that uses legs with adhesive feet for climbing vertical surface. The second one is a tread based locomotive mechanism using a rubber belt in place of a chain tire.

In order to achieve good performances, an optimization analysis was performed. The properties of tail and the position of the center of the mass were optimized. Finite Element Methods (FEM) was chosen for solving and optimizing the over constrained model. In the FEM model, the climbing robots were schematized by means of three beam elements having null masses. The gravitational force was applied in the center of mass of the system.

The results of the optimization correspond to a vehicle having the same dimensions of the developed tank robot. The force varies changing the length and the rigidity of the tail of the model depicture. The attaching force has a monotone behavior with respect to the Young’s modulus but there is a local minimum for the tail length. The optimal tail length should be 0.12 meter long and the Young’s modulus should be the highest possible.

Synthetic Hair Fabrication og Gecko Robot

As a first step in the synthetic Gecko fiber fabrication it is necessary to develop techniques to create the micro and nano-fibers independently. Once this is accomplished, it is possible to begin integrating the two types of fibers into a single process. The final structure will be a micro-fiber with nano-fibers branching out the end of the micro-fiber.

The first fabrication method utilizes commercially available components while the second method utilizes MEMS techniques to fabricate custom master molds. In both methods, liquid polymer is poured over the molds and cured. The cured molded polymer emerged in the desired physical form. It is possible to approximate the physical characteristics of the beta keratin by selecting the proper polymer.

Results from this method are promising. 200nm diameter high aspect ratio fibers have been produced, which are similar to the distal hairs found in Geckos robot. It is clear that there is bunching or matting occurring between the fibers increases, the inter fiber adhesion force surpasses the spring force of the fiber to remain upright and the fibers begin to bunch. This problem is caused by the high aspect ratio of the commercially available nanopore membrane as well as the high density. To avoid this bunching issue, a second method of fabrication was developed in which the density, diameter and length could be independently controlled. This method entails patterning a silicon wafer through photolithography and using a deep reactive ion etch to create a negative mold for the fibers.

Gecko Surface Climbing Robot

For over 2 millennia, humans have watched lizards and bugs scale vertical surfaces in awe. Only recently the attachments mechanisms of these animals have been understood. It is now possible to use similar mechanisms to allow robots to climb in the same manner as these animals.

Robot Geckos ability to climb surfaces, whether wet or dry, smooth or rough, has attracted scientists attention for decades. By means of compliant micro/nano-scale high aspect ratio beta-keratin structures at their feet, geckos manage to adhere to almost any surface with a controlled contact area. It has been shown that adhesion is mainly due to molecular forces such as van der Waals forces.

The Geckos ability to stick to surfaces lies in its feet, specifically the very fine hairs on its toes. There are billions of these tiny fibers which make contact with the surface and create a significant collective surface area of contact. The hairs have physical properties which let them bend and conform to a wide variety of surface roughness, meaning that the adhesion arises from the structure of these hairs themselves.

The structure of the biological Gecko foot-hair is very complicated and miniscule. Each fiber is made from multiple sections. Each fiber consist of a micro hair which is roughly 5 microns in diameter, and atop each of these micro-fibers sit hundreds of nano-fibers which are 200 nanometers in diameter. There are between 100 and 1000 nano-fibers on the end of each micro-hair.

Wall Climbing Robot for Thin Surfaces

The robot described here was designed for inspecting gas tanks that are made out of thin metal sheets and are installed in huge ships. From time to time, they have to be analyzed for leaks, especially at the welds. For doing this, helium is injected n the surrounding structure from outside. A sensor that can detect this helium then is move to all places inside the tank to find the position of the leak. Until now, this sensor was carried by a balloon that was operated manually, using some ropes. As this method was very slow and imprecise, a better inspection system, preferably consisting of a climbing robot on magnetic wheels, had to be developed.

As the environment can not support much force, the main goal was to make this robot as light as possible. And other consideration is the surface also considered to be very fragile. To simplify the control and increase the reliability, another method was using only few actuators. To ensure a correct functionality, the most critical risks were analyzed. This analysis does not only incorporate the possibility of some components within the robot breaking down. It also account for the risks of plastically deforming the environment, falling or slipping.

Clinical Implementation and Acceptance Issues on Robotic Surgery

Safety is an obvious concern for robotic surgery, and regulatory agencies require that it be addressed for every clinical implementation. As with most complex computer controlled systems, there is no accepted technique that can guarantee safety for all systems in every circumstance. Various robotic systems approach the problem in different ways. One common technique is to include passive and active safety mechanism in the mechanical design of the manipulator.

The end of the robot arm is attached to the endoscope through a gimbal and a magnetic coupling. Because the incision prevents lateral motion of the endoscope tube, as the robot moves the endoscope in space above the patient, the gimbal allows the endoscope tube to pivot about the incision. This makes it impossible for the robot to apply lateral forces on the incision. The magnetic coupling acts as an emergency release: if forces on the endoscope exceed the magnetic holding force, the endoscope disconnects and falls onto the patient’s abdomen, which is unlikely to cause injury.

Safety features of the software portion of the systems are also essential. In the context of a urology robot, it is used mathematical logic to analyze program flow and determine if it is possible for control to evade the safety features incorporated into the code. N addition, they implemented a completely independent safety monitor that can arrest a servo runaway and detect out of safe boundary conditions, using joint encoder signals as input.

Technical Issues Sensing and Control on Surgery Robotics

In tele-operated systems for minimally invasive or microsurgical procedures, there is substantial room for improvement of control and sensory feedback interfaces. In general, the human factor aspects of these systems have been little studied. Research questions include mater manipulator configuration, mapping between master and remote robot coordinate systems, scaling laws for micromanipulation systems, and video, force, and tactile feedback fidelity and bandwidth requirements.

Image-guided procedures have been an area of great success for robotic surgery, but there are many unresolved issues. Improved automatic segmentation and planning systems promise to improve efficiency and accuracy. Areas for improvement in registration include elimination of invasively placed fiducials and methods for non-rigid registration and tracking of tissue deformation in real time. The use of 2D imaging modalities such as ultras sound in combination with 3D tracking may lower costs and enable wider application of image-guided techniques.

For autonomous robotics in general, almost all successful applications over the past three decades have come in areas where tasks are narrowly specified and the environment is predictable, as in manufacturing. The early success of robotics in orthopedic surgery is due at least in part to the fact that bones are essentially rigid and relatively straightforward to manipulate, immobilize and cut.

Development of Robot Technology for Students

As technological and electronics artifacts integrate ever more tightly in our lives, it is disquieting to note that engineering enrollment continue to drop throughout the US. Even more alarming is that women participate in dismally low number in fields such as computer science and engineering, whereas virtually all science and business fields show significant improvement in terms of female participation.

One popular movement to stem the current tide evolves out of recognition that the pipeline is both the source of today’s trends and the strategic place of leveraging real change; improve the technology literacy of students at the primary and secondary level.

Robotic has served as a popular vehicle fir such pipeline-based technology literacy programs because of its ability to attract and inspire the imagination of students who are often unmotivated by conventional classroom curricula. There is no doubt that some of the students have found the contest-driven problem solving experience to be transformative. However these existing pipeline-focused technology literacy programs share a number of features that may limit participant diversity: they are short term, high intensity, competition driven, and technology focused.

Ny technological fluency, it means the ability to manipulate technology creatively and for one’s own use. We believe that the focus on fluency-building activities, which encourage creativity and personal adaptation of technology, will engage a more diverse student population with technology and engineering.

Spherical Mechanism of Surgical Robot

Recent advance in technology have led to the fusion of MIS techniques and robot devices. However, current systems are large and cumbersome. Optimizing the surgical robot mechanism will eventually lead to its integration into the operating room of the future becoming the extended presence of the surgeon and nurses in a room occupied by the patient alone. By optimizing a spherical mechanism using data collected in vivo during MIS procedures, this study is focused on a bottom-up approach to developing a new class of surgical robotic arms while maximizing their performance and minimizing their size.

The spherical mechanism is a rotational manipulator with all axes intersecting at the center f sphere. Locating the rotation center of the mechanism at the MIS port makes this class of mechanism a suitable candidate for the first two link of a surgical robot for MIS. The required dexterous workspace (DWS) is defined as the region in which 95% of the tool motions are contained based on in-vivo measurements.

The extended dexterous workspace (EDWS) is defined as the entire abdominal cavity reachable by a MIS instruments. The DWS is defined by a right circular cone with a vertex angle of 60o and the EDWS is defined a cone with an elliptical cross section created by two orthogonal vertex angle 60' and 90'.

Robot Surgical Application on Orthopedic Surgery

Orthopedics was one of the first areas of surgery in which robot applications were developed. Compared with soft issues, bones are relatively easy to manipulate and deform little during cutting, so image guided techniques are relatively straightforward to implement. The result is that robotic procedures can result in far better agreement with a preoperative plan than with the analogous manual procedure. Orthopedic applications that have received the greatest attention are hip and knee replacement and spinal fusion; additional work is under way in a variety of other areas, including craniofacial reconstruction and fracture treatment.

The replacement of hip joints that have failed as a result of disease or trauma has become common place. The procedure begins with disarticulation of the joint and removal of the proximal head of the femur. A metal and polymer prosthetic cup is then placed in the acetabulum.

In the current manual procedure, the surgeon cuts the cavity by forcing handheld broaches and reamers into the femur, which leaves a rough and uneven surface. The need for improved precision led to the creation of a robotic approach to forming the femoral cavity. Development of the ROBODOC system began in the mid-1980’s, and it is now commercially available in Europe and is undergoing FDA approval trial in United States.

The system provides two advantages. First clinical trials have confirmed that the femoral pocket is more accurately formed. Second, because of the need to provide precise numerical to the robot, preoperative CT images are used to plan the bone-milling procedure.

Robot Surgical Application on Neurosurgery

Neurosurgery was the first surgical specialty to use image-guided techniques, beginning with stereotactic frames that were attached to the patient’s cranium before the imaging process and remained in place during surgery. The relationship between the frame and lesion observed in the image was used to guide the instruments within the brain. Newer image-guided techniques, sometimes called frameless stereotaxy, use less invasive fiducially markers or video images for registration and optical trackers for navigation of hand-held instruments. To enhance stability, accuracy and ease of use, a number of robotic systems have been developed for these procedures.

One issued in image-guided neurosurgery is shifting of the brain during the procedure, which alters the spatial relationship between the preoperative image data and the anatomy of the patient. Various solutions have been proposed to deal with this problem, including deformable templates for non-rigid registration, sometimes base on biomechanical models of soft tissue. Another solution is to perform the procedure inside an imaging system, which permits continuous monitoring of the anatomy and instrumentation. This requires robotic manipulators that are compatible with the imaging modality and space constraints.

Radiosurgery uses a beam of radiation as a surgical instrument to destroy brain tumors. If the angle of incidence of the beam is pivoted through a large range, the beam passes through the tumor at all times but intersects each point of adjacent tissues only briefly.

Robotics Minimally Invasive Surgical Procedures

Several surgical specialties have been rapidly transformed by minimally invasive surgery. A central example is laparoscopic cholecystectomy, or gallbladder excision, a common procedure that is executed almost exclusively using minimally invasive surgery techniques. Surgeons work through a set of three to five incisions approximately 1 cm in size. Long-handled instruments are used to grip and cut tissue within the body, and a video laparoscope provides a view of the internal operating field.

Because this procedure avoids the long incision through abdominal wall used in the conventional open procedure, patients recover more quickly. Benefits include greatly reduced discomfort, improved cosmesis, reduced convalescence and hospitalization costs, and less time away from productive work.

The necessity of working through a few fixed incisions places severe limitations on dexterity in manipulation, and only a few procedures are possible with the current hand-held instruments. Lateral movement of the instrument shaft is not possible at the incision, which thus act as a fulcrum, reversing the directions of the surgeon’s hand motions at the instrument tip and varying the mechanical advantage as the instruments move in and out. The video monitor is often located on the far side of the patient, and the difference in orientation between the endoscope and the monitor requires the surgeon to perform a difficult mental transformation between visual and motor coordinate frames. Contact force perception is impaired by friction and varying mechanical advantage at the incision, and distributed tactile information is absent.

Surgery Robotics Technology Development

Over the past decade, robots have been appearing in the operating room. Robotic technology is now regularly used to aim endoscopes in minimally invasive surgery and to guide instruments to tumors in brain surgery. The use of a robot to shape bones in hip replacement surgery was one of the groundbreaking applications. Base on three dimensional (3D) computed tomography images, the surgeon plans the location of the prosthetic replacement joint within the femur.

In surgery, the robot moves a high speed cutting tool to form the precise shape specified in the pre-surgical plan. The result is a far better fit between the bone and replacement joint than has been possible with conventional hand held cutting instruments.

One reason surgical applications are progressing quickly is the large technology base that has been developed in robotics research in the past three decades. Result in mechanical design, kinematics, control algorithms, and programming that were developed for industrial robots are directly applicable to many surgical applications. Robotic researchers have also worked to enhance robotic capabilities through adaptability and autonomy. The resulting sensing and interpretation techniques that are proving useful in surgery include methods for image processing, spatial reasoning and planning, and real-time sensing and control.

TekBot System Modeling and Simulation

The TekBot is part of the Oregon State University (OSU) platforms for learning concept, created to teach students about analog circuitry, digital logic, and embedded systems – all in the context of robotic system design. This system modeling techniques are using the System Vision simulation environment produced by Mentor Graphics.

Modeling with VHDL-AMS and SPICE models, simultaneously, is a significant benefit in exploring and understanding the interactions of the different hardware devices on the TekBot. In addition to modeling the basic TekBot, additional hardware was modeled that would allow the TekBot to find and sort 5 orange balls and 5 black balls into color coded corners in a 10”X10” arena.

System modeling and simulation can be useful in projects such as this one, particularly when there are non-trivial interactions between subsystems. Co-verification of hardware and software was very beneficial. Finally, modeling of the system context proved to be invaluable for this project.

To enable the TekBot to sort the randomly placed balls in the arena, hardware was needed that would not only meet the power requirements of the battery operated system, but would also allow the TekBot to find and move all of the balls in the arena in a timely fashion. To find the balls quickly, a range finder was mounted on the front of the TekBot to determine the approximate distance to an object. The Daventek SRF-08 ultrasonic range finder was chosen because it was fairly inexpensive and operated on the I2C interface, which is a 2-wire communications protocol supported by the microcontroller used on the TekBot.

Methodology of TekBot Development

To read the color of an object, a simple analog circuit was developed that produces a voltage proportional to the intensity of light reflected from a surface. This output voltage is processed by the TekBot’s microcontroller through the on-board Analog to Digital converter. The source of the reflected light comes from 3 individual LEDs: red, blue and green. The readings taken from each source are then used to determine the surface color. The flexible solution provides recognition of a broad system spectrum of colors and shades, even though the system specification required only recognition of orange, black, blue and white.

The ball capture subsystem was developed using two servos controlling gate arms that enclose a ball and allow the TekBot and ball to roll together, maneuvering as necessary around the arena.

Preliminary design of these sensors and actuators included development of VHDL-AMS models. System Vision was used to verify that these subsystems would work correctly in the context of the full system. This step involved creating schematics that included the individual sensor or actuator subsystem and the necessary power, stimulus, and loads for various test conditions.

These schematic test-benches were then tested, via System Vision simulation, to observe the circuit’s behavior. The waveforms obtained by simulation provided the required visibility into both the models and the subsystem design – any deficiencies were corrected and verified through simulation.

FANUC Robotics M-420iA and M-421iA

The M-420iA is a four axis, modular construction, electro servo-driven robot with 40 kg payload and a remote control unit. The M-420iA is designed for variety of high speed manufacturing applications including picking, packing, palletizing, material handling, machine load and unload, and part transfer. FANUC robotics also offers the M-421iA, a two axis variant of the M-420iA. The waist and wrist axes have been removed, making the M-421iA faster and able to handle payload as high as 50Kg.

The M-420iA and M-421iA offer the fastest motion speed in their class, which result in reduced cycle time and improved productivity. The demonstration will highlight the robot’s high speeds, increased flexibility, and cell control compared to typical packaging machinery.

With the four axis M-420iA, up to two motors of servo conveyors or servo hand operations can be connected to the FANUC standard servo amplifier with no additional hardware. The two-axis M-421iA can have four additional motors. Integrating the additional auxiliary servo motors can help simplify the cell by utilizing one controller to run the complete cell. It will also help to reduce system costs by eliminating the need for extra servo control hardware/software. The robots can reach speeds significantly faster than previous generation packaging robots.

FANUC Robotics Solution Arm

The M-420iA robot uses FANUC’s V-500iA/2DV vision software to highlight the advantages of using visual line tracking to pick three randomly located parts from a moving conveyor. Visual line tracking provides the flexibility to handle multiple products on the same automation line, eliminating the need for costly fixtures, and reducing changeover time. The M-6iB/2HS robot uses line tracking to pick parts one at a time at high speeds, and place each part into a chute. The parts will drop from the chute back onto the conveyor at random locations and orientations.

FANUC robotics continues to address the need for greater flexibility and speed. To meet the need, there’s a growing trend towards equipping robots with vision systems. Vision significantly reduces the cost of fixturing and collating, and increases the customer’s ability to change to a new product quickly.

FANUC robotics recently introduced the M-6iB/6S solution arm robot. The Solution Arm is the latest member of the popular M-6iB/6S robot series, which offers several model variations and enhanced performance options to meet the needs of customers with high speed, light weight applications for assembly, part transfer, picking and packing.

FANUC robotics unique Solution Arm offers a revolutionary method of solving the routing of air lines and electrical connections to the end of arm tool.

Robot Programming Framework

Our goal is to supplement or replace existing code development methods. So it is necessary to select one or more popular robot programming tools to integrate in the Integrated Development Environment (IDE) tool, so that the user does not have to develop all robot code from scratch.

The selection of a popular tool is critical to ensure that the IDE can be immediately useful to the maximum number of robot developers. During development a robot simulation environment is useful for debugging. Testing with real robots is also important, so the tools must be able to control some of the robots available in the laboratory. The presence of both simulation and management capabilities within a single tool suite is preferable, simplifying IDE integration and allowing developers to switch between simulated testing and real testing transparently.

The player/stage robot simulation and management suite was eventually chosen. It has a simple but powerful network-based interface, and comprises both simulation and management capabilities.

The player and stage robot simulation suite is ideally suited to our IDE development project. It is a combined open-source robot management server and simulation tool. Player is the robot server, and stage is the simulator.

Robots communicate with the Player server, which provides a unified interface for robot control programs to access. These programs connect to the player server over standard network protocols.

Stream System of Integrated Development Environment

The stream system is the backbone of the IDE. It takes data from a single producer, such as the network spy decoder, and copies it to any number of registered consumers, such as the visualization tools.

Data from the network spy is classified by source address, destination address and packet type. Thus there could be a sonar data stream being forwarded from the player server to the robot program. The sonar visualization tool registers as a consumer of this stream, and so will be sent a copy of all the packets posted to this stream.

Streams are intended to be conceptual rather than physical divisions of data, and so they are not created or managed separately. If a packet is transmitted which does not fit in to any existing stream, a new stream is automatically created. It is also possible for consumers to register for streams that do not yet exist. This allows developers to set up visualizations before they start debugging their program. It is also possible to register for stream using wildcards for selection criteria.

It is important to note that a developer could easily create their own type of stream and pass data through it to the debug tools. The developer needs simply to register as a consumer of a sonar stream, process the data, and post the average values to a new type of stream.

The Criteria on the Integrated Development Environment

In order to focus on the Integrated Development Environment (IDE) aspects specific to robotic programming, it is important to base the new IDE on an existing framework. This framework must provide code editing and basic debugging functionality. Frameworks under consideration were judged on five criteria:
1. Support for the Phyton scripting language is essential, so it can use the RADAR real unit extensions to the language. Additionally, Phyton is a flexible rapid-development language well suited to robotics research.
2. An open source license is also a requirement. This permits modifications the underlying code of the framework as well as a simplified distribution model.
3. Robotic development takes place across a wide variety of platforms. It felt that this should be reflected by adopting a cross-platform approach to the IDE. This meant that the base framework must be supported across a minimum of two platforms, preferably Linux and Windows.
4. As the project is intended to expand on the base functions of the IDE, the extend ability of the chosen framework is also important. Although an open source platform permits modification to the IDE source code, this is not an optimal solution; ideally the basis for the IDE will support such extensions without source modifications.
5. Finally, the IDE chosen must both be in popular use to ensure ongoing development and support and be user friendly. That is, it must include such modern IDE features as syntax highlighting and project management.

Methods in Developing and Testing Robot Programs

The first step was to evaluate the processes currently involved in developing and testing robot programs. Although these processes are individual and differ subtly between developers, there are elements common to all.

All developers require a code editor, a debugger, and either a robot simulator or a robot management tool. Additionally many developers employ some form of visualization or data viewing tool to show data produced or sensed by the robot.

One problem with this approach is that it requires the management of a number of separate tools by the developer. The tools must be loaded and configured before any development can proceed. This is a time consuming and menial process.

Additionally, the developer is provided with very little in the way of useful debugging information. Most bugs must be diagnosed by writing code specifically to output the state of the program and the robot around the failure point. Once the problem has been resolved, this code becomes redundant and represents wasted development time.

Part of the problem is that robots are complicated systems that operate in real time. The majority of programming tools assume that it is possible to freeze execution of the program while debugging takes a place. As robots operate in the real world, this is often not an option.

To resolve the issues, integration of the wide range of tools used in robot programming is essential. The code editor, debugger, simulator and visualizations must all be accessible from within the IDE.

Conceptual Components for Robot Programming Systems

Programmers of robot arms and other complex articulated automatic devices must also deal with non-intuitive geometry. Programmers of mobile robots must deal with varied and unpredictable conditions as the robots moves through its environment.

Standard debugging tools give programmers access only to program data. This makes debugging robot programs difficult because program data is at best an indirect representation of the robot and environment.

The robot programming systems must be tailored more specifically to robotic, paying attention to the varied requirements of robot programs, the typical skills of robot programmers, the interactions between humans and robots, and the predominant programming constructs in robotic applications.

Robot programming systems have three important conceptual components that are of interest to their designers:
• The programming component, including designs for programming language, libraries and application programming interfaces (APIs).
• The underlying infrastructure including designs for architectures that support and execute robot behavior descriptions.
• The designs of interactive systems that allow the human programmer to interact with the programming component, to create, modify and examine programs and system resources, both offline and during execution.

There are other components that are not of particular concern to designers of robot programming systems, such as the robots themselves, operating systems, compilers, robot hardware drivers and so on.

Integrated Robotic Programming Environment

One of the difficulties facing robotic research and development is the dearth of integrated toolsets for facilitating robot programming. A wide variety of individual tools exist, but the developer must manage them all independently of their actual development environment. The goal is to extend a programming IDE to include integrated robot programming tools in much the same way as most IDEs include an integrated code debugger.

Robots have become increasingly complex and their controller increasingly powerful, yet robotic programming tools have not advanced as rapidly. Robots must be programmed both at the development stage to create the functionality of the robot, and in the field to customize the robot to applications, environment and tasks. It is important that robots become easier to program do that their potential may be fully realized.

Robot researchers face difficulties developing software systems for robots that are to assist humans in everyday environments. Much of the software is proprietary, there is a lack of open standards to promote collaboration and code reuse, and there is a lack of techniques for bringing the human in to the robot’s perceived environment.

The difficulty is the complex interactions robots have in real environment including:
• A large number of devices for input, output and storage.
• Simultaneous and unrelated activity on many inputs and outputs.
• The requirement to operate in real-time.
• Unexpected real world conditions.
• Wide variations in hardware and interfaces.

Software Architecture and System Identification

At present, to demonstrate the functionality of the hardware, the software supports tele-operation control from a workstation consisting of two SensAble Technologies Phantom 3.0 input devices and a foot pedal arrangement.

Developed as a personal robotics programming platform, this robot will be the site for extensive further work in all aspects of robotics involving mobile manipulation tasks. The software is currently being extended for use as a software development platform focusing on the technologies required to enable the types of personal robotics applications outlined.

System Identification and evaluation, since PR-1 is designed to work in human environments, its specifications are approximately human-like, with some improvements (such as the continuously rotating wrist joint), and some simplifications, such as the use of wheels instead of humanoid legs.

The Manipulator Safety Index (MSI) developed by Zinn gives an indicator of the likelihood that a manipulator will cause severe injury in the event of contact with a human head. The driving variables are the manipulator’s effective inertia, impact velocity, and interface stiffness. For PR-1, these variables were experimentally determined and their realistic ranges are listed. The MSI range for PR1 has a very low risk of serious injury compared to industrial robots such as the PUMA-560.

Power System and Controller Architecture of Robot

Power electronics and batteries in the base allow for 4 to 8 hours of typical autonomy, depending on the operational situation and task being performed. The system can draw 2kW peak power and 1kW continuously. Smart battery technology allows for computer monitoring of charge state and fast charges from a 110/220VAC electrical outlet. The computer electronics and all of the motor drives are located in the back of the torso.

All wiring is designed to be internal to the robot structure, although the first prototype still contains external loops across the elbow and shoulder joints. The gripper, since it features continuous rotation, has a small multi-slipring connector for motor power and encoder signal transfer.

The software communications architecture is a flexible and extensible system that handles data flow between functional modules. The communication layer handles inter process communication on one computer and across many computers, enabling the robot to leverage computer resources both on and off the robot. The layer is implemented on different operating systems and programming languages for maximal flexibility.

The prototype has two computers onboard. One computer handles non real-time functions, and the other computer runs a real-time operating system based on Linux and RTAI and implements a full dynamic model of the robot. This computer communicates in real time with the motor drive stacks over wired Ethernet at a 1 kHz rate for each motor.

Novel Arm Actuation System of Robot PR-1

The upper and lower arm links of each arm have redundant actuation mechanism that act in concert to provide both payload capacity and safety in unstructured environments: a gravity compensation system and joint torque actuators.

The gravity compensation system, grounded in the base of the arm, passively floats the arm and payload throughout workspace of the arm. This reduces the ned for large joint motors in the arm segments and enables the use of backdrivable transmissions, which is imperative for human and robot safety in unstructured environments.

This gravity compensation system uses compression springs, highly-geared, small motors and steel cables mounted to the arm segments in an innovative kinematic arrangement that provides passive gravity compensation throughout all arm configurations with a one degree of freedom payload set point adjustment, similar in concept to other mechanisms in rehabilitation and human service robot designs.

The gravity compensation system uses a geometry-based principle to linearize the force required to counter the angle-dependent effect of gravity of a mass on a rotating joint, effectively allowing the arm to passively float throughout its workspace. The system achieves as effect similar to that of a mass counter balance without the additional inertia, utilizing springs instead of masses to store the required potential energy. Each arm counter balance mechanism has an additional actuated degree of freedom to adjust for the payload to be counter-balanced.

Robot PR-1 Overall Configuration

Mobility: while fully holonomic (omni-directional) drivetrains exist, no existing system provides robust performance in real-world situations, i.e., able to move over doorway thresholds, curbs and extension cords. The design of PR-1 couples a 2-DoF differentially-driven base with torso rotation to approximate holonomic motion for the two 7-DoF arms mounted on the upper torso. With this 2-wheeled base, the indoor-environment robot can drive smoothly at speeds up to human walking speed of 2 m/s, bump over 1 – 2 cm obstacles such as carpeting, thresholds and cords, and allow the arms to be positioned virtually anywhere in a natural human-like configuration.

The base includes two pneumatic-tire wheels with 6Nm continuous torque to each wheel, enabling a climbing capability of 8o. The base also includes two suspension caters, the batteries, power electronics and chargers. The base and the torso are coupled by a 43 cm vertical lead-screw and a + 60o vertical axis rotating joint.

Manipulation: to manipulate objects that are common in work and home settings, PR-1 has two arms with ranges of motion and force similar to human arms, each with a simple gripper capable of typical human-like grasps. Designed to avoid pinch points or external wiring, a modular approach makes it possible to add specialized hardware and end effectors. The two arms are mounted to the torso on + 60o vertical axis joints.

The Three Characteristic of Robot System

Human safety: the system must be safe enough to work in human environments around humans. Achieving this level of safety requires both the hardware and software systems to be integrally designed from the beginning of the design process. Mechanical design safety includes minimizing inertia, providing back-drivability, eliminating pinch points, carefully managing kinetic and potential energies as well as force output, and making appropriate material selection.

Robustness: in order to develop real world applications for robotics, we believe that, while simulation is a powerful tool for coding high-level software, developers must be able to implement and test their program in a real robot. To this end the robot meeds to be robust. For example it must be able to gracefully handle unexpected environmental conditions and buggy software commands without any down time.

Payload: up to now, robots have been strong and massive or weak and light, but never strong and light. Payload ratios for human sized industrial robots are on the order of 1:10, compared to a human arm ratio of approximately 1:1. Our system has a human-like payload ratio through an innovative gravity compensation mechanism that reduces structural weight, electric motor mass and torque requirements, while still accommodating heavy loads. The accomplishment of an order of magnitude reduction in structural mass has significant implication in safety, usability, and appropriateness of use in human environments.

The Robotic Design of PR-1

Fundamentally, for a robot to be useful in human environments and perform tasks for people, It needs to have capabilities similar to humans. The following is a subset of the applications for which the research and development using PR-1 is being planned:
• Around the house: doing the dishes, tidying up, handling laundry, cleaning.
• Aging populations: carrying heavy things, remembering where things are, retrieving items, preparing food, cleaning.
• Assisting people with disabilities: tele-manipulation, feeding, doing chores, monitoring health and activity.
• Operations: Behind the counter food service, pick and pack tasks, stocking grocery stores, tracking inventory, retrieving items, maintaining a searchable physical file system.

From our analysis of these applications, a set of minimum capabilities was derived that includes the following:
• Support loads of 50N (10Lbf) with one arm.
• Grasp, carry and place a standard brick with one arm.
• Use both arms to move a full pot of water from one counter to another.
• Open doors, cabinets, drawer with one hand.
• Navigate wheelchair-accessible areas and handle common obstacles.

In addition to constraints imposed by individual tasks the goal of performing these types of tasks drives the following characteristics of the entire system: human safety, robustness, and payload.

Personal Robotic Development Platform

The many research robots developed generally classified into two categories:
1. Humanoid robot research platform is generally focuses on bipedal locomotion or human-robot interaction before manipulation, resulting in robots that are not designed to demonstrate practical manipulation performance.
2. Robot arm-and-gripper test beds that allow research on manipulating real objects. These research prototypes or modified industrial robots are not consumer-grade, human-safe or robust enough to be considered true development platforms.

Successful robot designs result from a tight coupling with the specific application space targeted by the developer. Robots designed, for example, for industry, space, surgery, and rehabilitation have significantly different operational criteria. The application space driving the design of this robot is broadly defined as human scale manipulation tasks in human environments.

Achieving functionality and safety in the variety of unstructured environments encountered in this application space presents a challenge since system behavior is dictated by software, not a human operator.

Software does not exist yet to perform the decision making humans do when dealing with safety, though this is an active area of research. To advance the area of personal robotics, for which assuring human safety is not optional and can not be handled through software alone, the mechanical design of the robot must be the ultimate safeguard.
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