Remote Manipulator System Research Articles

Inverse kinematics and multi-objective configuration optimization of the SSRMS manipulator

The Space Station Remote Manipulator System (SSRMS) type redundant manipulator with higher flexibility and foldability is widely used in the space environment. Inverse kinematics and multi-objective configuration optimization are analyzed in this paper. An arm angle parameterized inverse kinematics method using the approximate solution and error compensation scheme is proposed, which has the advantages of not requiring a selection of initial estimates of joint variables, being insensitive to Jacobian matrix singularities, having no pose error, and finding multiple solutions. In addition, Multiple Objective Particle Swarm Optimization (MOPSO) scheme is adopted to optimize the arm angle trajectory in null space, and the optimization index is set as joint torque and manipulability. Unlike traditional trajectory planning methods, we synthesize null space and configuration control to provide a novel perspective for trajectory planning. Finally, the experiments prove that the inverse kinematics algorithm is efficient and reliable, and the effectiveness of the configuration optimization method is verified by the numerical simulation of single objective and multi-objective optimization.

WebRTC-based MOSR remote control of mobile manipulators.

This article describes a contribution to the field of telerobotics via the Internet through the development of a web-based platform allowing the remote control of robots by multiple users, simultaneously. It also deals with minimizing the execution times of tasks by reducing connection and interaction delays. For this purpose, the Web Real-Time Communication (WebRTC) technology is utilized. The developed remote manipulation system allows the operators to visualize the robot, its surroundings and the data incoming from its sensors, and to carry out basic tasks, either independently by the manipulator or by the mobile robot, or jointly by both mechanical sub-systems. In addition, to ensure the control of the remote robot by several operators simultaneously, a priority system managing parallel tasks and a chat system between the operators have been proposed. Besides, many teams are able to exploit the robot, concurrently. The WebRTC-based Multiple Operator Single Robot (MOSR) telerobotic platform is validated on the emulator of the RobuTER/ULM mobile manipulator through various scenarios of primitive tasks over the Internet.

Inverse kinematics and workspace analysis of a novel SSRMS-type reconfigurable space manipulator with two lockable passive telescopic links

This study proposes a novel space station remote manipulator system (SSRMS)-type reconfigurable space manipulator to enhance the adaptability of the traditional SSRMS-type manipulators in complex on-orbit tasks. The proposed manipulator has two lockable passive telescopic links (LPTLs) and allows changing their lengths to achieve reconfigurability. The inverse kinematics (IK) and the workspace for this manipulator are minutely analyzed. We develop a new CCDJAP-IK method to solve the IK problem by combining the cyclic coordinate descent (CCD) and joint angle parameterization (JAP) methods. This new method addresses the CCD method's convergence instability and the JAP method's high dependence on the pre-set value of the redundancy parameter. In particular, our approach is insensitive to the initial and singular configurations and can generate multiple exact solutions that satisfy the joint limit constraints. A reachability sphere map captures the proposed manipulator's kinematic capability for the workspace analysis. Then the effects of the two LPTLs on this capability are deeply explored. Based on the results, we propose an information-driven optimal configuration search method. Several typical simulations validate the proposed methods’ effectiveness.

Grappling Spacecraft

This article provides a survey overview of the techniques, mechanisms, algorithms, and test and validation strategies required for the design of robotic grappling vehicles intended to approach and grapple free-flying client satellites. We concentrate on using a robotic arm to grapple a free-floating spacecraft, as distinct from spacecraft docking and berthing, where two spacecraft directly mate with each other. Robotic grappling of client spacecraft is a deceptively complex problem: It entails designing a robotic system that functions robustly in the visually stark, thermally extreme orbital environment, operating near massive and extremely expensive yet fragile client hardware, using relatively slow flight computers with limited and laggy communications. Spaceflight robotic systems are challenging to test and validate prior to deployment and extremely expensive to launch, which significantly limits opportunities to experiment with new techniques. These factors make the design and operation of orbital robotic systems significantly different from those of their terrestrial counterparts, and as a result, only a relative handful of systems have been demonstrated on orbit. Nevertheless, there is increasing interest in on-orbit robotic servicing and assembly missions, and grappling is the core requirement for these systems. Although existing systems such as the Space Station Remote Manipulator System have demonstrated extremely reliable operation, upcoming missions will attempt to expand the types of spacecraft that can be safely and dependably grappled and berthed.

Precise semi-analytical inverse kinematic solution for 7-DOF offset manipulator with arm angle optimization

Seven-degree-of-freedom redundant manipulators with link offset have many advantages, including obvious geometric significance and suitability for configuration control. Their configuration is similar to that of the experimental module manipulator (EMM) in the Chinese Space Station Remote Manipulator System. However, finding the analytical solution of an EMM on the basis of arm angle parameterization is difficult. This study proposes a high-precision, semi-analytical inverse method for EMMs. Firstly, the analytical inverse kinematic solution is established based on joint angle parameterization. Secondly, the analytical inverse kinematic solution for a non-offset spherical-roll-spherical (SRS) redundant manipulator is derived based on arm angle parameterization. The approximate solution of the EMM is calculated in accordance with the relationship between the joint angles of the EMM and the SRS manipulator. Thirdly, the error is corrected using a numerical method through the analytical inverse solution based on joint angle parameterization. After selecting the stride and termination condition, the precise inverse solution is computed for the EMM based on arm angle parameterization. Lastly, case solutions confirm that this method has high precision, and the arm angle parameterization method is superior to the joint angle parameterization method in terms of parameter selection.

A Novel Analytical Inverse Kinematics Method for SSRMS-Type Space Manipulators Based on the POE Formula and the Paden-Kahan Subproblem

Space manipulators which have a similar symmetrical structure with seven revolute joints, such as the space station remote manipulator system (SSRMS), can be called SSRMS-type space manipulators. The analytical inverse kinematics of an SSRMS-type manipulator can be solved by locking a single joint; the locked joint (joint 1, 2, 6, or 7) can be determined by configuration analysis. Although widely used in establishing the kinematics of SSRMS-type manipulators, the Denavit-Hartenberg (DH) method has a singular problem when two adjacent joint axes are nearly parallel. To avoid this problem, this paper proposes a novel analytical inverse kinematics method for SSRMS-type manipulators based on the product of exponentials (POE) formula and the Paden-Kahan subproblem. Because of the symmetrical structure, an SSRMS-type manipulator degrades to two kinds of 6-degree-of-freedom (DOF) manipulators when locking a single joint (joint 1, 2, 6, or 7). The analytical inverse kinematics of these two kinds of 6-DOF manipulators is solved by combining the Paden-Kahan subproblems and geometric and algebraic methods, respectively. The proposed approach is not only singularity free compared with the traditional DH-based methods but also more accurate than the POE-based numerical solution. The simulation results verify the efficiency of the proposed approach.

Charging of the H-II Transfer Vehicle at Rendezvous and Docking Phase

The Japan Aerospace Exploration Agency developed an instrument consisting of a potential monitor and a plasma current sensor to measure the potential of the H-II transfer vehicle (HTV) against ambient plasma and the plasma environment around the HTV. In this first report on the charging measurements on the HTV-6 (sixth flight of H-II transfer vehicle), the onorbit data obtained during the rendezvous and docking phase are discussed, as well as the subsequent releasing phase. The trends observed during docking and releasing suggest the worst potential in terms of values never seen before over the full lifetime of the HTV-6. The cause is inferred to be resistance of the space station remote manipulator system as a result of numerical calculations based on simplified models of the HTV and the International Space Station.

Robot-assisted totally endoscopic coronary bypass surgery

Totally endoscopic coronary artery bypass (TECAB) surgery can exclusively be undertaken with the aid of operative robots. In the past two decades, surgical remote manipulator systems—predominantly the daVinci® devices—have brought us the reality of endoscopic internal mammary artery harvesting and coronary bypass anastomoses via minimally invasive thoracic port access. Single up to quadruple TECAB interventions are recently feasible; the procedure can be delivered either as beating heart applying endoscopic vacuum stabilizer or under cardioplegic arrest on heart-lung machine. Significant surgical team learning curves are involved in a stepwise development of these complex procedures, including intense dry- and wet-lab trainings, endoscopic internal mammary artery harvesting and manual coronary anastomosis building through a thoracotomy. Increasing number of papers have been published regarding clinical TECAB series in the past decade. In arrested heart TECAB procedures on cardiopulmonary bypass, the conversion rate from port access to larger thoracic incision measures 15.1% and no perioperative mortality is observed in published records. Stroke, kidney failure and atrial fibrillation rates stay at 0.6, 0.4 and 12.9%, respectively. Analysis of beating heart TECAB procedures revealed a conversion rate of 15.3%, perioperative mortality 0.4%, stroke 0.3%, kidney failure 0.6% and atrial fibrillation 9.2%. Additionally, due to the obviously smaller surgical trauma, a remarkable fast return to normal daily activities can be demonstrated in clinical series of robotic assisted coronary bypass surgery. Short-term freedom of major adverse cardiac and cerebral events (MACCE) stays over 90%. Long-term studies reveal 5-year freedom of MACCE in the 75.2 to 83.1% range. Nowadays, total endoscopic coronary artery bypass grafting is a feasible and reproducible surgical method. Advanced hybrid coronary interventions offer complex multivessel TECAB with support of percutaneous coronary interventions (PCI). Combination of the above techniques widens the spectrum of minimally invasive therapeutic solutions concerning multivessel procedure including bilateral internal mammary grafts and drug-eluting stents.

Effect of remote controlled injection manipulator system assisted percutaneous kyphoplasty for treatment of rupture of posterior vertebral osteoporotic vertebral fracture

To evaluate the effect of remote controlled injection manipulator system (RCIM) assisted percutaneous kyphoplasty (PKP) for the treatment of rupture of posterior vertebral osteoporotic vertebral fracture by comparing with intermittent hand bolus injection of bone cement during operation. Between September 2010 and January 2016, a retrospective analysis was made on the clinical data of 48 senile patients with single segment rupture of the posterior vertebral osteoporotic thoracolumbar fracture undergoing PKP who accorded with the inclusion criteria. Of 48 patients, 22 received intermittent hand bolus injection of bone cement in the control group, and 26 received RCIM assisted bone cement perfusion in the trial group. There was no significant difference in age, gender, duration of disease, causes of injury, implicated vertebral bodies, bone mineral density T value, pain duration, preoperative visual analogue scale (VAS), relative vertebral body height in the anterior part, and posterior convex Cobb angle between groups ( P>0.05). The bone cement perfusion time, the radiation dose of both doctors and patients, and the amount of bone cement injection were recorded; treatment effects were evaluated based on VAS score, posterior convex Cobb angle, relative ver-tebral body height in the anterior part, ratios of bone cement diffusion area and bone cement leakage rate. The patients were followed up for 6 months; no complications of toxic effect of bone cement, spinal cord or nerve root injuries, infection and vascular embolization occurred during follow-up period. There was no significant difference in bone cement injection amount and radiation dose of doctors between groups ( P>0.05), but bone cement perfusion time, ratios of bone cement diffusion area, and radiation dose of patients were significantly lower in the trial group than the control group ( P<0.05). Bone cement leakage was observed in 6 cases of the control group (27.27%) and 2 cases of the trial group (7.69%), showing significant difference between groups ( χ2=4.850, P=0.029); no cement leakage into the spinal canal was found in both groups. VAS score, relative vertebral body height in the anterior part, and posterior convex Cobb angle were significantly improved at 3 days and 6 months after operation when compared with preoperative ones ( P<0.05), but no significant difference was observed in the above indexes between groups at 3 days and 6 months after operation ( P>0.05). Satisfactory effectiveness can be achieved by applying RCIM assisted PKP for the treatment of rupture of posterior vertebral osteoporotic vertebral fracture. RCIM can shorten perfusion time, reduce radiation dose, and decrease incidence of bone cement leakage.

極限作業用ロボットハンドのための遠隔操作マニピュレーションシステムの開発

極限作業用ロボットハンドのための遠隔操作マニピュレーションシステムの開発

A review of the end-effector of large space manipulator with capabilities of misalignment tolerance and soft capture

The space manipulator which has advantages of high dexterity and universality, is used to the space capturing usually. According to the different types of mechanical interfaces of targets, the on orbit capturing operation includes capturing of cooperative target and capturing of uncooperative target. The performances of the famous large space manipulators named space shuttle remote manipulator system (SRMS), the space station remote manipulator system (SSRMS) and the Europe robotic arm (ERA) are reviewed and studied respectively. Moreover, the space manipulators being developed by China for space station is also surveyed. Based on the performance analysis of the large space manipulators and end-effectors, which are adapted to the construction and daily maintenance for the large space structure such as the space station, the basic requirements of large misalignment tolerance capability, soft capturing capability and hard docking capability for the end-effector of large space manipulator are proposed in this paper. According to these requirements, the capture mechanism and methods that can enable the end-effector to have the capability of misalignment tolerance and soft capturing are presented. The development trend and key technologies of the large space manipulators and the end-effectors are also reviewed.

Radiation safety and ergonomics in the electrophysiology laboratory: update on recent advances.

Risks associated with exposure to ionizing radiation in patients undergoing electrophysiology procedures and interventional cardiac electrophysiologists performing these procedures are a serious concern. Strategies to reduce radiation exposure are of obvious importance. In addition, interventional cardiac electrophysiologists have to perform procedures wearing heavy lead protection for prolonged periods, making them prone to cervical and lumbar spinal injuries. Recently developed technologies, such as low-exposure radiographic imaging, novel radiographic imaging protection systems, nonfluoroscopic mapping systems using image integration, and remote catheter manipulation systems have been successful in reducing ionizing radiation exposure in the electrophysiology laboratory. The efficacy and safety of these technologies are being evaluated in clinical trials. In addition, economic analyses are being performed to evaluate these novel systems. The use of nonweight-bearing radiation protection devices and ergonomic design of the electrophysiology laboratory aim to reduce the incidence of occupational injuries in interventional cardiac electrophysiologists. There is need for ongoing development and evaluation of new technologies to minimize exposure to ionizing radiation during electrophysiologic procedures. In addition, ergonomic planning of the electrophysiology laboratory and training of interventional cardiac electrophysiologists are crucial to occupational injury prevention.

Fault-tolerant analysis and control of SSRMS-type manipulators with single-joint failure

Several space manipulators, whose configurations are similar to that of the Space Station Remote Manipulator System (SSRMS, also called Canadarm2), are playing important roles in the construction and maintenance of the International Space Station. Working in the harsh orbital environment, they are at high risk of single-joint failure. Fault-tolerant capability is critical for those manipulators to complete their on-orbital tasks.In this paper, we analysed and compared the manipulation capability of SSRMS-type manipulators with joints locked at arbitrary positions, and proposed efficient path planning via a fault-tolerant control method. First, a unified kinematic model of this type of manipulators was established. Second, the manipulation capability of the original 7-DOF (degrees of freedom) redundant manipulator was analysed and compared with its degraded 6-DOF counterparts formed by different joint locking configurations. Then, we identified those joints with large sensitivity to fault tolerance performance. The influences of different positions of all joints were also determined by numerical computation. Based on the analysis, the relatively safe and dangerous regions for each joint failure were identified. Finally, we proposed a path planning strategy and realized by a H∞ controller which enables the failure joint locked in the safe region, and simulations were carried on a degraded 3-DOF planar redundant manipulator to verify the planning strategy and control approach. This paper provided important analysis results and efficient methods to address the possible problems of SSRMS-type manipulators caused by single-joint failure that can be extended to other types of manipulators. Moreover, the proposed method is useful for designing the optimal configuration of a redundant manipulator.

Analytical and semi-analytical inverse kinematics of SSRMS-type manipulators with single joint locked failure

Redundant space manipulators, including Space Station Remote Manipulator System (SSRMS), Special Purpose Dexterous Manipulator (SPDM) and European Robotic Arm (ERA), have been playing important roles in the construction and maintenance of International Space Station (ISS). They all have 7 revolute joints arranged in similar configurations, and are referred to as SSRMS-type manipulators.When a joint is locked in an arbitrary position due to some failures, a 7R manipulator degrades to a 6R manipulator. Without a spherical wrist or three consecutive parallel joints, the inverse kinematics of the 6R manipulator is very complex. In this paper, we propose effective methods to resolve the inverse kinematics for different cases of any joint locked in an arbitrary position. Firstly, configuration characteristics of the SSRMS-type redundant manipulators are analyzed. Then, an existing of closed-form inverse kinematics is discussed for locking different joints. Secondly, D–H frames and corresponding D–H parameters of the new 6-DOF manipulator formed by locking a joint in an arbitrary position are re-constructed. A unified table is then created to describe the kinematics for all possible cases of single joint locking failure. Thirdly, completely analytical and semi-analytical methods are presented to solve the inverse kinematics equations, and the former is used for locking joint 1, 2, 6 or 7 while the latter for locking joint 3, 4 or 5. Finally, typical cases for single joint locking are studied. The results verify the proposed methods.

Development and verification of ground-based tele-robotics operations concept for Dextre

The Special Purpose Dextreous Manipulator (Dextre) is the latest addition to the on-orbit segment of the Mobile Servicing System (MSS); Canada's contribution to the International Space Station (ISS). Launched in March 2008, the advanced two-armed robot is designed to perform various ISS maintenance tasks on robotically compatible elements and on-orbit replaceable units using a wide variety of tools and interfaces. The addition of Dextre has increased the capabilities of the MSS, and has introduced significant complexity to ISS robotics operations. While the initial operations concept for Dextre was based on human-in-the-loop control by the on-orbit astronauts, the complexities of robotic maintenance and the associated costs of training and maintaining the operator skills required for Dextre operations demanded a reexamination of the old concepts. A new approach to ISS robotic maintenance was developed in order to utilize the capabilities of Dextre safely and efficiently, while at the same time reducing the costs of on-orbit operations. This paper will describe the development, validation, and on-orbit demonstration of the operations concept for ground-based tele-robotics control of Dextre. It will describe the evolution of the new concepts from the experience gained from the development and implementation of the ground control capability for the Space Station Remote Manipulator System; Canadarm 2. It will discuss the various technical challenges faced during the development effort, such as requirements for high positioning accuracy, force/moment sensing and accommodation, failure tolerance, complex tool operations, and the novel operational tools and techniques developed to overcome them. The paper will also describe the work performed to validate the new concepts on orbit and will discuss the results and lessons learned from the on-orbit checkout and commissioning of Dextre using the newly developed tele-robotics techniques and capabilities.

2510 直感的操作可能な遠隔操作型メリクロンマニピュレータの開発

In this study, we developed the intuitive remote controlled manipulator system using touch panel display and mouse, and we examined the possibility of the application to the extraction work of the shoot apical meristem of the plant. The shoot apical meristem does not have the infection of the virus in the plant body. Therefore we can get a Virus-free seedling having high production efficiency by culturing this part. This technique is called "mericlone" and is known widely in the agriculture world, but this is hard labor because of precision work with microscope. This system we have developed not only reduce the burden on worker but also provide high precision controlling and space saving. In this study, with LAMP method (loop-mediated isothermal amplification method), we have confirmed that there was no PVX (Potato virus X) in the potato meristem with primordia using our developed manipulator system The newly designed primer set can discriminate the result.

Vision-Based Haptic Feedback for Remote Micromanipulation in–SEM Environment

This article presents an intuitive environment for remote micromanipulation composed of both haptic feedback and virtual reconstruction of the scene. To enable nonexpert users to perform complex teleoperated micromanipulation tasks, it is of utmost importance to provide them with information about the 3-D relative positions of the objects and the tools. Haptic feedback is an intuitive way to transmit such information. Since position sensors are not available at this scale, visual feedback is used to derive information about the scene. In this work, three different techniques are implemented, evaluated, and compared to derive the object positions from scanning electron microscope images. The modified correlation matching with generated template algorithm is accurate and provides reliable detection of objects. To track the tool, a marker-based approach is chosen since fast detection is required for stable haptic feedback. Information derived from these algorithms is used to propose an intuitive remote manipulation system that enables users situated in geographically distant sites to benefit from specific equipments, such as SEMs. Stability of the haptic feedback is ensured by the minimization of the delays, the computational efficiency of vision algorithms, and the proper tuning of the haptic coupling. Virtual guides are proposed to avoid any involuntary collisions between the tool and the objects. This approach is validated by a teleoperation involving melamine microspheres with a diameter of less than 2 μ m between Paris, France and Oldenburg, Germany.

1A2-J07 宇宙大型マニピュレータによる宇宙ステーション補給機「こうのとり」捕獲時の運動解析(【宇宙工学部門】宇宙工学とロボティクス・メカトロニクス(1))

1A2-J07 宇宙大型マニピュレータによる宇宙ステーション補給機「こうのとり」捕獲時の運動解析(【宇宙工学部門】宇宙工学とロボティクス・メカトロニクス(1))

An Intelligent Simulator for Telerobotics Training

Roman Tutor is a tutoring system that uses sophisticated domain knowledge to monitor the progress of students and advise them while they are learning how to operate a space telerobotic system. It is intended to help train operators of the Space Station Remote Manipulator System (SSRMS) including astronauts, operators involved in ground-based control of SSRMS and technical support staff. Currently, there is only a single training facility for SSRMS operations and it is heavily scheduled. The training staff time is in heavy demand for teaching students, planning training tasks, developing teaching material, and new teaching tools. For example, all SSRMS simulation exercises are developed by hand and this process requires a lot of staff time. Once in an orbit ISS astronauts currently have only simple web-based material for skill development and maintenance. For long duration space flights, astronauts will require sophisticated simulation tools to maintain skills. Roman Tutor addresses these challenges by providing a portable training tool that can be installed anywhere and anytime to provide “just in time” training. It incorporates a model of the system operations curriculum, a kinematic simulation of the robotics equipment, and the ISS, a high performance path planner and an automatic task demonstration generator. For each element of the curriculum that the student is supposed to master, Roman Tutor generates example tasks for the student to accomplish within the simulation environment and then monitors its progression to provide relevant feedback when needed. Although motivated by the SSRMS application, Roman Tutor remains applicable to any telerobotics system application.

「きぼう」ロボットアームの開発成果( 「きぼう」で獲得した有人宇宙技術 第19回)

「きぼう」ロボットアームの開発成果( 「きぼう」で獲得した有人宇宙技術 第19回)