Effective Workspace Research Articles

Dynamic model and workspace analysis of novel incompletely restrained cable-suspension swing system driven by two cables

The incompletely restrained cable-suspension swing system driven by two cables is introduced in this article. Based on wrench of forces theory and Lagrange’s equation of first kind, the static and dynamics models of incompletely restrained cable-suspension swing system driven by two cables are established, respectively. In order to obtain an intuitive understanding of the trajectory analysis, a dynamics model consisting of governing equation and geometric constraint conditions which is a set of the mixed differential-algebraic equation in mathematics is established. A typical feedback controller and an inverse model were set up to estimate the driving function. The effective workspace, which is used to guarantee an efficient swing process, mostly depends on the geometrical shape rather than the volume itself which was calculated by trajectory analysis. In order to estimate system features and ensure a limited range of tension in underconstrained spatial cable system, the probable location of unbalanced loading was evaluated by pointwise evaluation techniques during normal work.

Cooling capacity and acoustic performance of radiant slab systems with free-hanging acoustical clouds

Radiant slab systems have the potential to achieve significant energy savings, yet, when applied in the ceiling (e.g., thermally activated building system) the exposed concrete may also create acoustical challenges due to the high reflectivity of the hard surface. Balancing all of the building indoor environmental quality factors is important in the design of an effective workspace for the occupants, and so we need to consider the interactions between thermal and acoustic comfort. We assessed the cooling capacity in a hydronic test chamber and the sound absorption in a reverberation chamber to study the effects, for an office room, of different coverage areas of free-hanging acoustical clouds below a radiant chilled ceiling. The cooling experiments showed that for 47% cloud coverage of the ceiling area, we measured only an 11% reduction in cooling capacity caused by the blockage of radiant exchange between the ceiling and the room. The acoustical results showed that if the cloud covered 30% of the ceiling in a private office or 50% in an open plan office, acceptable sound absorption at the ceiling was achieved. We showed that good acoustic quality can be achieved with only a minor reduction of cooling capacity.

Impact of standard-pressure and low-pressure pneumoperitoneum on shoulder pain following laparoscopic cholecystectomy: a randomised controlled trial.

The incidence of shoulder pain (SP) following laparoscopic cholecystectomy (LC) varies between 21 and 80%. A few randomised controlled trials and meta-analysis have shown lesser SP in LC performed under low-pressure carbon dioxide pneumoperitoneum (LPCP) than under standard-pressure carbon dioxide pneumoperitoneum (SPCP). However, the possible compromise in adequate exposure and effective working space during LPCP has negatively influenced its uniform adoption for LC. All consecutive patients undergoing elective LC for gallstone disease who met the inclusion and exclusion criteria were enroled. Fourty patients were randomised to SPCP group (pressure of 14mmHg) and 40 to LPCP group (pressure of 9-10mmHg). Primary outcome measured was incidence of SP and its severity on visual analogue scale (VAS) at 4, 8, 24h and 7days after LC. Secondary outcomes measured were procedural time, technical difficulty, surgeons' satisfaction score on exposure and working space, intra-operative changes in heart rate and blood pressure, abdominal pain and analgesic requirement. Analyses were performed using Stata software. There was no conversion to open surgery, bile duct injury or need to increase intra-abdominal pressure on either group. Twenty-three patients (57.5%) in SPCP group and nine patients (22.5%) in LPCP group had SP (p=0.001). The severity of SP was significantly more in SPCP group at 8 and 24h (p=0.009 and 0.005, respectively). Both the groups had similar procedural time, surgeons' satisfaction score, intra-operative changes in heart rate and blood pressure. The incidence and severity of SP following LC performed at LPCP are significantly less compared to that in SPCP. The safety, efficacy and surgeons' satisfaction appear to be comparable in both the groups. Hence, a routine practice of low-pressure carbon dioxide pneumoperitoneum may be recommended in selected group of patients undergoing laparoscopic cholecystectomy. CTRI/2016/02/006590.

Preliminary Design of a Robotic System for Catching and Storing Fresh Market Apples

Abstract: This paper presents the preliminary design of a two-link planar manipulator for fresh market apple catching. Rather than use the harvesting manipulator to place picked apples in a storage container, the secondary system catches and stores apples at the point of fruit separation in order to minimize path length and improve cycle time. Monte Carlo simulations were used to select link lengths and joint limits. The design includes two low cost stepper motors and a vacuum assisted end-effector. After fabrication, laboratory studies were conducted to measure the system’s repeatability and validate the proof-of-concept. A conservative estimate of repeatability is 20 mm, which is within the catching end-effector’s effective workspace. During integrated system testing in the lab, the secondary system caught all harvested fruit. Likewise, the pick-and-catch technique resulted in an approximately 50 percent reduction in overall cycle time compared to the conventional pick-and-place method. Future work will include development of an end-effector prototype with soft elements to minimize fruit bruising.

Kinematics Analysis of a Novel Five-Degree-of-Freedom Spatial Parallel Micromanipulator

A study of the inverse kinematics for a five-degree-of-freedom (DOF) spatial parallel micromanipulator is presented here below. The objective of this paper is the introduction of a structural and geometrical model of a novel five-degree-of-freedom spatial parallel micromanipulator, analysis of the effective and useful workspace of the micromechanism, presentation of the obtained analytical solutions of the microrobot’s inverse kinematics tasks, and verification of its correctness using selected computer programs and computation environments. The mathematical model presented in this paper describes the behaviour of individual elements for the applied 2-DOF novel piezoelectric actuator, resulting from the position and orientation of the microrobot’s moving platform.

Workspace Analysis of a Novel Parallel Robot Named 3-R2H2S with Three Freedoms

In order to meet the sorting and packing needs of the drug and food industries, a novel parallel robot mechanism named 3-R2H2S is proposed in this study, the kinematics equation of the robot was deduced and the inverse kinematics was calculated. The workspace model of the robot is analyzed by the boundary search method through the MATLAB and ADAMS kinematics software. The analysis results show that the robot has a large effective workspace with smooth boundary and can be widely applied in the field of industrial robots, the kinematics of micro robots and 3D coordinate measurements and the workspace of the robot can meet the needs of drug and food automation production line.

任意点で操作可能な多リンクパワーアシストシステムの操作点運動協調化制御

We have proposed a Multi-portal Human Interface (M-HI) as an innovative human interface for power assist systems (PAS). The M-HI allows users to apply the operational force anywhere on the power assist system. Because of that, the effective workspace of the PAS is extended as their end-effecter can be controlled as a user desires. However, when users control the PAS on its intermediate joint, the control point motion is different from the end-effecter motion. This motion affects maneuverability of the PAS. In this paper, we consider the number of links and degrees of freedom on a multi-link manipulator. The relation between the control point motion and maneuverability is analyzed. The operational point motion harmonization (OPMH) is based on this relation. This method enables users to control the PAS with M-HI more accurately.

Trans-Oral Video-Assisted Neck Surgery (TOVANS). A new transoral technique of endoscopic thyroidectomy with gasless premandible approach

BackgroundEndoscopic thyroidectomy is a well-established surgical technique. We have been utilizing precordial video-assisted neck surgery (VANS) with a gasless anterior neck skin lifting method. Recently, natural orifice transluminal endoscopic surgery (NOTES) has generated excitement among surgeons as potentially scar-free surgery. We developed an innovative gasless transoral technique for endoscopic thyroidectomy that incorporated the concept of NOTES in a VANS-technique.MethodsIncision was made at the vestibulum under the inferior lip. From the vestibulum to the anterior cervical region, a subplatysmal tunnel in front of the mandible was created and cervical skin was lifted by Kirschner wires and a mechanical retracting system. This method without CO2 insufflation created an effective working space and provided an excellent cranio-caudal view so that we could perform thyroidectomy and central node dissection safely.ResultsBeginning with our first clinical application of TOVANS in September 2009, we have performed eight such procedures. Three of the eight patients had papillary microcarcinoma and received central node dissection after thyroidectomy. All patients began oral intake 1 day after surgery. The sensory disorder around the chin persisted more than 6 months after surgery in all patients. Recurrent laryngeal nerve palsy revealed in one patient. Nobody had mental nerve palsy, and no infection developed with use of preventive antibacterial tablets for 3 days.ConclusionsWe developed a new method for gasless transoral endoscopic thyroidectomy with a premandible approach and anterior neck-skin lifting. TOVANS makes possible complete endoscopic radical lymphadenectomy for papillary thyroid cancer. We believe that this method is innovative and progressive and has not only a cosmetic advantage but also provides easy access to the central node compartment for dissection in endoscopic thyroid cancer surgery.

Manual movement coordination adapted to spinal cord injury and low back pain

Spinal cord injury (SCI) and low back pain (LBP) significantly limit personal and occupational activities. Since upper body movements are crucial to extend hand reach envelopes and maintain postural balance, coordinated control of torso and hand movements is essential. In this study, adapted patterns of coordination were investigated in SCI, LBP and control participants performing seated manual material handling tasks, in which a load was transferred with both hands from a home location to one of 4 targets in the mid-sagittal plane.Torso peak velocities are larger and delayed for the SCI when compared to the control group, while hand peak velocities are comparable. However, hand peak velocities are smaller in the LBP than control group. Hand movements generally precede torso movements for all groups, but more prominently for the SCI than the other groups. Furthermore, for SCIs torso movements were suppressed until the hands were aligned with target elevation.These results indicate that SCI individuals have developed a unique coordination pattern to compensate for their limited balance control, although this strategy may reduce their effective workspace and overload the upper extremities. In contrast, LBPs seem to have reduced movement speed while their coordination patterns are generally similar to those in the control group. Relevance to industryThis study analyzed movements of persons with spinal cord injury or low back pain in manual material handling tasks. Assessing their adapted movement strategies would help to improve workspace design to accommodate workers with limited capacities and to provide quantifiable evidence and guidelines on the effectiveness of occupational rehabilitation programs.

A workspace‐orientated needle‐guiding robot for 3T MRI‐guided transperineal prostate intervention: evaluation of in‐bore workspace and MRI compatibility

Magnetic resonance imaging (MRI)-guided prostate interventions have been introduced to enhance the cancer detection. For accurate needle positioning, in-bore-operated robotic systems have been developed and optimal use of the confined in-bore space become a critical engineering challenge. As preliminary evaluation of our prostate intervention robot, we conducted a workspace design analysis, using a new evaluation method that we developed for in-bore-operated robots for transperineal prostate interventions, and an MRI compatibility study. The workspace analysis resulted in the effective workspace (VW ) of 0.32, which is greater than that of our early prototype, despite the current robot being ca. 50% larger than the early prototype in sectional space. The MRI compatibility study resulted in < 15% signal:noise ratio (SNR) reduction. The new workspace evaluation method quantifies the workspace utilization of the in-bore-operated robots for MRI-guided transperineal prostate interventions, providing a useful tool for evaluation and new robot design. The robot creates insignificant electromagnetic noise during typical prostate imaging sequences.

A simulation and training environment for robotic radiosurgery

To provide a software environment for simulation of robotic radiosurgery, particularly to study the effective robot workspace with respect to the treatment plan quality, and to illustrate the concepts of robotic radiosurgery. A simulation environment for a robotic radiosurgery system was developed using Java and Java3D. The kinematics and the beam characteristics were modeled and linked to a treatment planning module. Simulations of different robot workspace parameters for two example radiosurgical patient cases were performed using the novel software tool. The first case was an intracranial lesion near the left inner ear, the second case was a spinal lesion. The planning parameters for both cases were visualized with the novel simulation environment. An incremental extension of the robot workspace had limited effect for the intracranial case, where the original workspace already covered the left side of the patient. For the spinal case, a larger workspace resulted in a noticeable improvement in plan quality and a large portion of the beams being delivered from the extended workspace. The new software environment is useful to simulate and analyze parameters and configurations for robotic radiosurgery. An enlarged robot workspace may result in improved plan quality depending on the location of the target region.

Three degrees-of-freedom joint for spatial hyper-redundant robots

We present a new mechanical design for a compact three degrees-of-freedom joint mechanism. This joint design is ideal for use in robotic devices, especially hyper-redundant or snake-like robots. This joint exhibits an unprecedented range of motion: the origin of a coordinate frame attached to the output link of the joint can move on a spherical cone whose apex angle is 120° and this coordinate frame can be rotated around an axis passing through its origin and the center of the sphere. Moreover, the joint is optimized for strength, compactness and accuracy. These characteristics are verified by exploring the magnitude of the wrenches and errors that the joint can produce in its effective workspace. Finally, we present a mechatronic integration of four of our joints to construct a 12 degrees-of-freedom spatial hyper-redundant robot.

Path Tracking of Parallel Manipulators in the Presence of Force Singularity

Parallel manipulators are uncontrollable at force singularities due to the infeasibly high actuator forces required. Existing remedies include the application of actuation redundancy and motion planning for singularity avoidance. While actuation redundancy increases cost and design complexity, singularity avoidance reduces the effective workspace of a parallel manipulator. This article presents a path tracking type of approach to operate parallel manipulators when passing through force singularities. We study motion feasibility in the neighborhood of singularity and conclude that a parallel manipulator may track a path through singular poses if its velocity and acceleration are properly constrained. Techniques for path verification and tracking are presented, and an inverse dynamics algorithm that takes actuator bounds into account is examined. Simulation results for a planar parallel manipulator are given to demonstrate the details of this approach.

A Design Methodology for the Compensation of Positioning Deviation in Gantry Manipulators

This work presents recent results concerning a design methodology used to estimate the positioning deviation for a gantry (Cartesian) manipulator, related mainly to structural elastic deformation of components during operational conditions. The case-study manipulator is classified as gantry type and its basic dimensions are 1,53m x 0,97m x 1,38m. The dimensions used for the calculation of effective workspace due to end-effector path displacement are: 1m x 0,5m x 0,5m. The manipulator is composed by four basic modules defined as module X, module Y, module Z and terminal arm, where is connected the end-effector. Each module controlled axis performs a linear-parabolic positioning movement. The planning path algorithm has the maximum velocity and the total distance as input parameters for a given task. The acceleration and deceleration times are the same. Denavit-Hartemberg parameterization method is used in the manipulator kinematics model. The gantry manipulator can be modeled as four rigid bodies with three degrees-of-freedom in translational movements, connected as an open kinematics chain. Dynamic analysis were performed considering inertial parameters specification such as component mass, inertia and center of gravity position of each module. These parameters are essential for a correct manipulator dynamic modelling, due to multiple possibilities of motion and manipulation of objects with different masses. The dynamic analysis consists of a mathematical modelling of the static and dynamic interactions among the modules. The computation of the structural deformations uses the finite element method (FEM).

Development of a micro-manipulation system having a two-fingered micro-hand

A dexterous micro-manipulation system has been developed for applications in assembling micro-machines, manipulating biological cells, and performing micro-surgery. We have proposed a micro-hand having two fingers, a prototype of which has been designed and built using parallel mechanisms. We discuss the structure of our micro-hand and its operation system. The structure of the two-fingered micro-hand is strongly related to its effective workspace. The design of the micro-hand has been influenced by consideration of the usage of chopsticks. A calibration method based on least-square error is proposed for three degrees of freedom (DOF) translational motion in task coordinates fixed under a microscope. Development of a useful operational device to control the micro-hand is important for achieving dexterous micro-manipulation. A force feedback system would be ideal for such manipulation. In the case of micro-manipulation, though, a sensor with high resolution and multiple sensing axes is needed. There is no sensor meeting this demand currently. In order to achieve micro-manipulation without the force feedback system, an operational system which can be controlled with natural operational feeling like manipulation of actual human hand, is important. We have developed an operational device which is controlled by one hand. The forefinger and thumb are used to manipulate microscopic objects in tele-operation. However, due to kinematic dissimilarity between the master and the micro-hand, the motion of the fingers cannot be directly used as operational signals to move the micro-hand. We have therefore developed an operational strategy which compensates for this dissimilarity, thus providing for easy manipulation.

Functional properties of graphic workspace: assessment by means of a 3D geometric arm model

Computer simulations aimed at assessing functional characteristics of the graphic workspace are presented. The simulations involve a 10-df kinematic model of the distal part of the writing arm, and yield the effective workspace of the pen tip under two types of kinematic constraints. The first constraint involves fixing the forearm under various pronation angles, the second governs the protrusion of the pen tip from the finger tips. The effective workspace is analyzed in terms of the effort required to reach the various locations in it, where effort is defined in terms of the joint angles adopted by the wrist and fingers to reach each location. The simulation results show agreements between the distribution of required effort over the workspace and known stroke-direction preferences in drawing. Furthermore, they predict shifts in the biases that are thought to lead to these preferences as a function of both hand pronation and pen protrusion.

二本指マイクロハンドの設計と微細作業

A prototype two-fingered micro hand is designed and is applied to the actual micro tasks. First, we discuss a concept of a two-fingered micro hand based on human usage of a pair of chopsticks. The two-fingered micro hand should be designed by considering the effective work space, or the common work space of two fingers, as well as the simplicity of its cooperation control for each finger. Our proposed prototype has two 6 DOF parallel mechanisms in series in order to realize similar motion in our chopsticks usage. We applied the prototype to practical micro manipulation tasks, and we succeeded in picking up a glass ball having size of 2 [μm] and placing it in arbitrary position under a microscope by human teleoperation.

96/03537 Desulphurization of coals by flash pyrolysis followed by magnetic separation

The selective separation, due to the interplay of gravity and magnetic forces, has been analysed for coexisting pairs of minerals, both of which are either paramagnetic or ferromagnetic. The extent of the maximum region of selectivity has been determined, and the influence of the dynamics of the separation process on the usable working space, within the region of selectivity, has been considered. The region of selectivity has also been determined for separators in which gravity has been replaced by centrifugal acceleration. The adoption of a non-Laplacian profile is proposed for the bipolar magnet used in such a separator. This may produce a more efficient system than standard profiles giving constancy of the gradient of either field or (field)2. Magnetic fluidization may provide a means of separating coexisting minerals which are so similar in the relevant property that the effective working space in a conventional separator becomes vanishingly small. The dynamics of the rotation of a magnetized particle in a uniform field has been considered. It is concluded that an alternating field must have a peak value, which lies in a range which is specific to one component of a mineral mixture, to selectively fluidize that component. When this condition is met for a ferromagnetic component, a coexisting paramagnetic phase is unlikely to fluidize.

Kinimatic Analysis of a New Clss of 6-DOF Parallel Manipulator

In this paper, a new kinematic structure of a parallel manipulator with six Cartesian degrees of freedom is proposed. It consists of a platform which is connected to a fixed base by means of 3-PPSP(parameters P, S denote the prismatic, spherical joints) subchains. Each subchain has a link which is concected to a passive prismatic joint at the one end and a passive spherical joint at the other. The spherical joint is then attached to perpendicularly arranged prismatic actuators which are fixed at the base. The spherical joint is then attached to perpendicularly arranged prismatic actuators which are fixed at the base. This arrangement provides a basis to control all six Cartesian degrees of motion of the platform in space. Due to its efficient architecture, the colsed-form solutions of the inverse and forward kinematics can be obtained. As a consequence, this new kinematic structure can be servo controlled using simple inverse kinematics becaese forward kinematics allows for measuring the platform's position and orientation in Cartesian space. Furthermore, the proposed structure provides an effective functional workspace. Series of simulations are performed to verify the results of the kinematics analyses.

Selectivity in the magnetic separation of minerals

The selective separation, due to the interplay of gravity and magnetic forces, has been analysed for coexisting pairs of minerals, both of which are either paramagnetic or ferromagnetic. The extent of the maximum region of selectivity has been determined, and the influence of the dynamics of the separation process on the usable working space, within the region of selectivity, has been considered. The region of selectivity has also been determined for separators in which gravity has been replaced by centrifugal acceleration. The adoption of a non-Laplacian profile is proposed for the bipolar magnet used in such a separator. This may produce a more efficient system than standard profiles giving constancy of the gradient of either field or ( field) 2. Magnetic fluidization may provide a means of separating coexisting minerals which are so similar in the relevant property that the effective working space in a conventional separator becomes vanishingly small. The dynamics of the rotation of a magnetized particle in a uniform field has been considered. It is concluded that an alternating field must have a peak value, which lies in a range which is specific to one component of a mineral mixture, to selectively fluidize that component. When this condition is met for a ferromagnetic component, a coexisting paramagnetic phase is unlikely to fluidize.