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Background: Chimeric antigen receptor (CAR) T cells have recently been demonstrated to extract and express cognate tumor antigens through trogocytosis. This process may contribute to tumor antigen escape, T cell exhaustion, and fratricide, which plays a central role in CAR dysfunction. We sought to evaluate the importance of this effect in epidermal growth factor receptor variant III (EGFRvIII) specific CAR T cells targeting glioma. Methods: EGFRvIII-specific CAR T cells were generated from various donors and analyzed for cytotoxicity, trogocytosis, and in vivo therapeutic activity against intracranial glioma. Tumor autophagy resulting from CAR T cell activity was evaluated in combination with an autophagy inducer (verteporfin) or inhibitor (bafilomycin A1). Results: CAR T cell products derived from different donors induced markedly divergent levels of trogocytosis of tumor antigen as well as PD-L1 upon engaging target tumor cells correlating with variability in efficacy in mice. Pharmacological facilitation of CAR induced-autophagy with verteporfin inhibits trogocytic expression of tumor antigen on CARs and increases CAR persistence and efficacy in mice. Conclusion: These data propose CAR-induced autophagy as a mechanism counteracting CAR-induced trogocytosis and provide a new strategy to innovate high-performance CARs through pharmacological facilitation of T cell-induced tumor death.

Archaeological isotope studies have traditionally been anthropocentric, with animals analyzed either as proxies or as baseline data in human-focused studies of diet and behavior. However, the value of analyzing animals in their own right is becoming increasingly clear for understanding human-animal-environment relationships. This chapter presents the results of a multi-species, multi-isotope investigation of animal remains recovered from Fishbourne Roman Palace (Sussex, UK). This extraordinarily high-status site, located at the edge of the Roman Empire, appears to have been a node through which exotic animals and new cultural attitudes to the natural world entered Britain. Here, we show how isotope analysis can be used to explore these ideologies, and reconstruct changing relationships between people, animals, and their environments.

Aim There has been a global movement towards transformation of youth mental health services, but limited information on the core principles and characteristics of these new services is available. Jigsaw is one such service, established in Ireland in 2006, with the intent of creating change in Ireland's system of mental healthcare for 12-25 year olds. The aim of this paper is to describe the evolution of Jigsaw services, which are now firmly embedded in the Irish system of care for young people, and recognized internationally as an established service network. Methods This paper describes provides an up-to-date description of the Jigsaw service model, key areas of evolution that have shaped this model, and identifies future directions in service development. Results Key attributes of the Jigsaw service model including therapeutic service, scope of practice, youth mental health promotion, youth participation, and monitoring/evaluation are described in this paper. Information on key enablers (funding and governance/quality) and service providers is also included. Conclusions Information on the core principles and characteristics of youth mental health services is important. This paper addresses a gap in the literature by describing the Jigsaw service model, which continues to evolve so that it is responsive to the needs of young people.

Discover a fresh take on classical screw theory and understand the geometry embedded within robots and mechanisms with this essential text. The book begins with a geometrical study of points, lines, and planes and slowly takes the reader toward a mastery of screw theory with some cutting-edge results, all while using only basic linear algebra and ordinary vectors. It features a discussion of the geometry of parallel and serial robot manipulators, in addition to the reciprocity of screws and a singularity study. All 41 essential screw systems are unveiled, establishing the possible freedom twists and constraint wrenches for a kinematic joint. Familiarizing the reader with screw geometry in order to study the statics and kinematics of robots and mechanisms, this is a perfect resource for engineers and graduate students.

BACKGROUND Advancements in bioengineering have allowed bispecific Abs to develop with therapeutic applications in immuno-oncology. Here we describe a fully humanized bispecific t cell engager (BiTE) that binds the GBM-associated antigen interleukin 13 receptor alpha 2 (IL13Rα2) and the T Cell receptor CD3 epsilon (CD3ε) to elicit an anti-tumor immune response in patient-derived models of GBM. METHODS In vitro, BiTE-mediated activation of T Cells was assessed via flow cytometry as measurements of T cell activation markers CD25 and CD69 and cytokines IFNγ and TNFα. BiTE-directed T cell-mediated cytotoxicity was assessed in GBM 6 and GBM12patient-derived xenograft lines. In vivo, GBM6 patient-derived xenograft cells were intracranially implanted in NSG-MHC I/II DKO mice, reconstituted with HLA-matched donor peripheral blood lymphocytes (PBMC), and subsequently treated with 2.5 mg/kg BiTE via i.p. injection x 4 days/week of therapeutic BiTE for three weeks. Animals were followed for survival, and the brains of long-term survivors were analyzed for residual disease and T cell infiltration. RESULTS In vitro, BiTE potently activated T cells as determined by a high expression of CD25 and CD69 and the production of TNFα and IFNγ. BiTE also directed T cell-mediated cytotoxicity against GBM cells in a dose-dependent manner, with significant activity still seen in the low nanogram range. In vivo, BiTE significantly extended the survival of tumor-bearing animals in GBM6patient-derived xenograft models. Histological analysis of long-term surviving mice shows complete absence of tumor and robust presence of CD8+ T cells localized to the original site of tumor implantation. CONCLUSIONS Our data demonstrate the efficacy of humanized BiTE in patient-derived GBM models, and our results support the investigation of this novel therapeutic in a clinical trial setting.FUNDING: R01 NS122395-01 and R01 NS095642-01

INTRODUCTION Given the limited drug penetration across the blood-brain barrier (BBB), the therapeutic potential of new and existing therapies has not been fully exploited for the benefit of glioblastoma (GBM) patients. METHODS Here we employed a novel drug delivery technology based on low-intensity pulsed ultrasound combined with intravenous microbubbles (LIPU/MB) that temporarily opens the BBB to deliver liposomal doxorubicin (DOX) and anti-PD-1 therapy (aPD-1) in mouse glioma models and 3 recurrent GBM patients. Immunological variables were evaluated in tumor and immune cells as well as efficacy in glioma-bearing mice treated with DOX delivered by LIPU. These included measurement of HLA ABC and HLA DR protein expression by tumor cells, microglia, and macrophages and IFN-g production by glioma-associated microglia and macrophages in mouse and human tumors. We also assessed efficacy of LIPU/MB enhanced combination therapy in glioma-bearing mice. RESULTS Upregulation of HLA ABC and HLA DR was observed in GBM cell lines at low concentrations of DOX. Tumor cells from GBM patients treated with DOX, aPD-1 and LIPU/MB showed increased expression of HLA ABC and HLA DR compared to paired pretreatment samples. In both mice and humans, LIPU/MB liposomal DOX increased absolute brain drug concentrations and elicited a specific IFN-g phenotype and MHC I expression in glioma-associated microglia and macrophages in mice and humans. Furthermore, LIPU/MB-mediated BBB opening increased brain concentrations of aPD-1 in mice and in peritumoral regions of GBM patients. Combined treatment with liposomal DOX and aPD-1 delivered with LIPU/MB resulted in long-term survival of glioma-bearing mice that relied on the activity of CD8+ T cells for its efficacy. CONCLUSIONS Overall, this translational study demonstrates the utility of LIPU/MB to stimulate intracranial immune responses in the context of treatment with DOX and aPD-1 for gliomas.

In children, diffuse midline gliomas retain poor outcomes, failing to have a durable response to conventional therapies. Immunotherapies hold promise, with the integration of the host's immune system fundamental to their design. Here, we describe a novel genetically engineered immunocompetent model that incorporates interleukin 13 receptor alpha 2 (IL13Rα2), a tumor-associated antigen, to evaluate the antitumor activity of IL13Rα2-CAR T cell and bispecific T cell engager (BiTE) therapies in preclinical studies. The RCAS-Tva delivery system was utilized to induce gliomagenesis through p53 loss and the constitutive expression of PDGFB and human IL13Rα2 in Nestin-Tva;p53fl/fl mice. Pups were injected with virus-producing DF1 cells, encoding either for RCAS-Cre and PDGFB+IL13Rα2 or RCAS-Cre and PDGFB. Kaplan-Meier survival curves established and compared tumor growth dynamics in both models. Tumor tissue was characterized through immunohistochemistry and H&E staining. Cell lines generated from tumor-bearing tissue were used for orthotopic injection and in vitro studies. Expression of PDGFB and IL13Rα2 was confirmed by flow cytometry and western blot. In both groups, de novo tumors developed without significant difference in median survival between RCAS:PDGFB (n=25, 40 days) and RCAS:PDGB+IL13Rα2 (n=32, 39 days). Tumors demonstrated characteristics of high-grade glioma such as infiltration, pseudopalisading necrosis, microvascular proliferation, high Ki-67 index, heterogenous IL13Rα2 expression, with notable presence of CD11b+ macrophages and low count of CD3+ T cells. Orthotopic tumors from developed cell lines were histologically similar to de novo tumors. Treatment of generated cell lines with IL13Rα2-targeting BiTE protein resulted in a loss of glioma cell viability and target-specific activation of T cells. Engineered de novo tumors possess histopathologic features common to diffused midline gliomas. IL13Rα2-positive cell lines derived from de novo tumors were responsive to targeted treatment, opening the opportunity for preclinical assessment of IL13Rα2-directed immunotherapies, with the potential for clinical translation.

Although mental health problems represent the largest burden of disease in young people, access to mental health care has been poor for this group. Integrated youth health care services have been proposed as an innovative solution. Integrated care joins up physical health, mental health and social care services, ideally in one location, so that a young person receives holistic care in a coordinated way. It can be implemented in a range of ways. A review of the available literature identified a range of studies reporting the results of evaluation research into integrated care services. The best available data indicate that many young people who may not otherwise have sought help are accessing these mental health services, and there are promising outcomes for most in terms of symptomatic and functional recovery. Where evaluated, young people report having benefited from and being highly satisfied with these services. Some young people, such as those with more severe presenting symptoms and those who received fewer treatment sessions, have failed to benefit, indicating a need for further integration with more specialist care. Efforts are underway to articulate the standards and core features to which integrated care services should adhere, as well as to further evaluate outcomes. This will guide the ongoing development of best practice models of service delivery.

Two problems are addressed in this paper. First, the mathematical model to perform the static analysis of an antiprism tensegrity structure subjected to a wide variety of external loads is presented. The virtual work approach is used to deduce the equilibrium equations and a method based on Newton’s Third Law is used to verify the numerical results. Two numerical examples are provided to demonstrate the use of the mathematical model, as well as the verification method. The second problem deals with the development of a mathematical model to perform the static analysis of a prestressed antiprism tensegrity structure subjected to an arbitrary length reduction of its connecting ties. Again, a virtual work approach is used to deduce the equilibrium equations and the numerical results are verified using a Newtonian approach. One example is provided to illustrate the mathematical model.

This paper investigates the soft-finger contact by presenting the contact with a set of line springs based on screw theory, reveals the rotational effects, and identifies the stiffness properties of the contact. An elastic model of a soft-finger contact is proposed and a generalized contact stiffness matrix is developed by applying the congruence transformation and by introducing stiffness mapping of the line springs in translational directions and rotational axes. The effective stiffnesses along these directions and axes are hence obtained and the rotational stiffnesses are revealed. This helps create a screw representation of a six-dimensional soft-finger contact and produce an approach of analyzing and synthesizing a robotic grasp without resorting to the point contact representation. The correlation between the rotational stiffness, the number of equivalent point contacts and the number of equivalent contours is given and the stiffness synthesis is presented with both modular and direct approaches. The grasp thus achieved from the stiffness analysis contributes to both translational and rotational restraint and the stiffness matrix so developed is proven to be symmetric and positive definite. Case studies are presented with a two-soft-finger grasp and a three-soft-finger grasp. The grasps are analyzed with a general stiffness matrix which is used to control the fine displacements of a grasped object by changing the preload on the contact.

Two types of trusses were optimized using the simple, yet powerful, mathematical technique of employing line geometry as defined by the mathematicians Plucker and Grassmann. The key benefit to this design methodology is simplicity. Multiple-node designs were analyzed, with particular focus placed on the triangular truss. The methodology is based on a geometric stability criterion called the quality index. This approach allowed for a simple equation to be created that identifies the optimal geometry based on the exterior angles and the number of sides. Trusses with single and double connecting points are considered using the quality index. An example of a double connection truss is the triangular truss. In this case, each node (either on the top or the base) has two structural elements connecting to the other nodes. It is shown that there are optimal design criteria for the upper, lower, and separation dimensions. These optimal geometric designs yield conical trusses. Further consideration of the 3-3 truss produced a closed-form solution. This equation holds significant potential for truss designs, providing a clear comparison between single and double connections.

This paper presents a methodology whereby the payload weight of a serial manipulator can be determined from a minimum set of sensor data, i.e., joint angle and joint torque measurements. The particular manipulator geometry that is analyzed is a four degree-of-freedom serial chain that is commonly used in excavator systems. It was quite remarkable that a relatively simple solution was obtained for the payload weight considering that there are a total of nine unknown moments and cross moments of inertia of the payload together with the unknown location of the center of mass. Example calculations are presented. © 2003 Wiley Periodicals, Inc.

This paper emphasizes the role of mathematical techniques that the Catastrophe Theory has recently provided as powerful tools for both the control and the design of compliant systems whose behavior is governed by a potential function. The problem of the identification of absolutely safe working areas as regards the stability of the equilibrium is addressed. An application example of such a theory to the stability analysis of a planar mechanism equipped with flexural pivots is carried out for the first time.

A review of a family of tensegrity structures that self-deploy from a stowed or packed configuration is presented. In the packed configuration, the mechanism is of a cylindrical form with the struts lying side by side. Such structures may be applied in the deployment of antennas in space and in the rapid deployment of shelters or tents. This family of structures evolved from a study of in-parallel platforms with compliant legs or connectors. A number of relevant references are cited.

This paper uses screw algebra to derive relatively simple and explicit expressions for the complex motion-invariant rotational first- and second-order geometric influence coefficients for a planar multi-loop mechanism in terms of reciprocal products of screws and differential screws. The concept of the differential screws is presented and used as an effective tool in characterizing the second-order geometric influence coefficients. Furthermore, the geometrical interpretation of both the screw product and the reciprocal product of screws in two-dimensional space is presented and implemented to simplify the formulation. It is believed that this is the first time to be able to derive the motion-invariant geometric influence coefficients of multi closed-loop mechanisms in explicit and relatively simple forms. The use of the geometric influence coefficients eases the kinematic and dynamic modelling problems of mechanisms. The derived simple expressions for geometric influence coefficients are then implemented to drive the angular velocity-squared/acceleration ratio of the output link. If the single-degree of freedom (dof) planar multi-loop mechanism is running with constant input velocity this ratio becomes motion-invariant too. An illustrative example is presented. This technique has the potential of being extended to cover other spatial and spherical mechanisms as well as multi-degree of freedom multi-loop mechanisms. It could also be extended to derive simple expressions for the translational geometric influence coefficients.

The octahedral manipulator is a "3-3" device that is fully in parallel. It has a linear actuator on each of its six legs. The legs connect an equilateral platform triangle to a similar base triangle in a zigzag pattern between vertices. Our proposed quality index takes a maximum value of 1 at a central symmet rical configuration that is shown to correspond to the maxi mum value of the determinant of the 6 x 6 Jacobian matrix of the manipulator. This matrix is none other than that of the nor malized line coordinates of the six leg-lines; for its determi nant to be a maximum, the platform triangle is found to be half of the size of the base triangle, and the perpendicular distance between platform and base is equal to the side of the platform triangle. When the manipulator is actuated so that the octahedron departs from this central configuration, the determinant al ways diminishes, and, as is well known, it becomes zero when a special configuration is reached (the platform then gain ing one or more uncontrollable freedoms). Our quality index λ, 0 ≤ λ ≤ 1, is a constructive measure of acceptable design proportions. The double-spherical joints (there are six) are the source of the critical practical difficulties. Kinematic substitutions can circumvent this problem, but often there is no reasonable alternative to accepting a reduction of maximum quality index through separation by fairly short distances of some or all of the double-ball joints. Too great a separation easily leads too far toward generality; any fully-in-parallel manipulator of more general proportions should be tested for quality against our octahedral form simply because no different form can be superior to a well-designed octahedron from the points of view of structural soundness and ability to apply both forces and controlled displacements to the end-effector platform.

An optimization approach to computing the boundaries of the workspaces of planar manipulators is presented. This numerical method consists of finding a suitable radiating point in the output coordinate space and then determining the points of intersection of a representative pencil of rays, emanating from the radiating point, with the boundary of the accessible set. This is done by application of a novel constrained optimization approach that has the considerable advantage that it may easily be automated. The method is illustrated by its application to two planar mechanisms, namely a planar Stewart platform and a planar redundantly controlled serial manipulator. In addition to the exterior boundaries of the workspace, interior curves that represent configurations at which controllability and mobility may be limited, are also mapped. The optimization methodology, implemented here for the planar case, may readily be extended to spatial Stewart platforms. [S1050-0472(00)00304-4]

A general method for the computation of the canonical form of three-systems of infinitesimal screws is presented. The method is particularly simple when the three-system has a basis that is simultaneously perpendicular and reciprocal. However, it can also handle the special or degenerate cases. The method and the concurrent results are important from the theoretical point of view because of the obvious connection with the classification of screw-systems. Moreover, the results are also important for applied kinematics after recent applications of the canonical form of screw-systems to the analysis and synthesis of manipulators and manipulator substructures.

A stability analysis is performed for the planar two-spring system using catastrophe theory. Basic elements of catastrophe theory are outlined and applied to the two-spring system to give catastrophe locus plots showing where a change in stability occurs. The method used for the two-spring yields a stability analysis without having to solve the inverse analysis. The inverse analysis for the two-spring system is used to illustrate system equilibrium positions before, dur ing, and after a change in stability.

This contribution presents a closed-form solution for the location of the acceleration center of a rigid body subjected to spatial motion. Moreover, all the special cases are deduced and analyzed by a systematic analysis of the conditions under which the closed-form solution cannot be computed. Finally, the results obtained here are compared with those previously published.

A reverse force analysis of a spatial three-spring system is presented which determines equilibrium positions when an external force is applied. The system consists of three linear springs, each of which is attached to the ground via pivots which form a triangular base. The three springs are joined at a common pivot at the other end, thus forming a tetrahedron. A known force is applied at the common pivot. The multiple equilibrium positions are computed by deriving and solving a 22nd degree polynomial in a single spring length. The degree of this polynomial is verified in the Appendix independently of the analysis, using geometry. Following this, corresponding pairs of the remaining two spring lengths are computed, which determine the multiple equilibrium positions. These results have been verified by numerical examples. The symbolic computation was performed by the computer algebra system MATHEMATICA.

In this article, a novel closed-form solution to the inverse analysis of a planar two-spring system is presented which may be extendible to the spatial three-spring system. It involves finding the six equilibrium configurations of a system of two springs connected at one end to a common pivot and at the other to a base. This formulation involves a transformation into polar coordinates where a sixth degree polynomial is obtained in terms of tan-half-angle for the rise angle of one of the springs. The derivation and the coefficients of this polynomial are much simpler than those obtained by Pigoski and Duffy, An inverse force analysis of a planar two-spring system, presented at the First Austrian IFTOMM Symposium, Seggauberg, Austria, July 4-9, 1993, also in press Trans. ASME where a sixth degree polynomial in one of the spring lengths was obtained.

It is well known that the velocity of the end effector of a serial chain can be written as a linear combination of the screws that represent, with respect to an arbitrary coordinate system, the kinematic pairs that join the end effector with the body used as the reference frame. In this paper, it is shown that the acceleration of a point in the end effector of the serial chain can be expressed in terms of the direction and moment parts of the same screw coordinates.; Further, is if the angular velocity of the end effector vanishes, then its acceleration can be written as a relatively simple expression involving only the complete screw coordinates themselves and their Lie products. Thus, the present work can be regarded in one sense as an extension of screw theory into the acceleration analysis of linkages. Furthermore, since the equations obtained here are tensorial, the present work can be also regarded as a step toward a coordinate free dynamic analysis, as suggested by Chevallier [Mech. Mach. Theory 26, 613–627 (1991)].

This paper presents a critical analysis of the metric of rigid body displacements obtained from the so-called kinematic mapping. It is shown that this metric is not suitable for finite rigid bodies. The paper also addresses the metrics obtained for the planar group, as it can be regarded as a subgroup of the group of all rigid body displacements, which is denoted here as the Euclidean group. Finally, the paper proposes some metrics for the set of spatial and planar displacements for a finite rigid body, undergoing a finite displacement.

La finalite de cette etude pilote est d'analyser le niveau de developpement du jugement moral des etudiants dans deux types d'universites a partir de lectures, de cours et de discussions. Le premier type d'universite implique une experience directe aupres de personnes en difficulte. Les AA. mettent l'accent sur deux problemes: les innovations du cursus pour les etudiants et les resultats de la recherche dans une universite traditionnelle. Leur volonte est de savoir si les etudiants ayant une experience pratique possedent une maturite plus grande dans le jugement moral

This paper presents a novel, practical, and theoretically sound kinematic control strategy for serial redundant manipulators. This strategy yields repeatability in the joint space of a serial redundant manipulator whose end effector undergoes some general cyclic type motion. This is accomplished by deriving a new inverse kinematic equation that is based on springs being theoretically or conceptually located in the joints of the manipulator (torsional springs for revolute joints, translational springs for prismatic joints). Previous researchers have also derived an inverse kinematic equation for serial redundant manipulators. However, to the authors’ knowledge, the new strategy is the first to include the free angles of torsional springs and the free lengths of translational springs. This is important because it ensures the repeatability in the joint space of a serial redundant manipulator whose end effector undergoes a cyclic type motion. Numerical verification for repeatability is done in terms of Lie bracket condition. Choices for the free angle and torsional stiffness of a joint (or the free length and translational stiffness) are made based upon the mechanical limits of the joint.

A kinematic analysis of a 6 degree of freedom (DOF) parallel manipulator which has three legs, mounted on moving sliders is described. Therefore, the 6 DOF are provided by the slider displacements and by changing the leg lengths. This manipulator structure provides a large functional workspace. A forward displacement analysis is performed by using a decomposition method and reduces to the one non-linear equation solution by using an interaction method. Two distinct reverse displacement analyses are given. A manipulator workspace determination and a method for the specification of the platform position in space.

A displacement analysis is performed for an in-parallel spherical manipulator. Forward and reverse displacement analyses are performed. Two distinct reverse displacement analyses are given: a manipulator workspace determination and a platform determination is given. The displacement analysis is performed by using a decomposition method.

This paper presents a method for reducing forward displacement analysis of in-parallel platform mechanisms to single univariate polynomials. The method based on one single model is shown to be applicable to the forward analysis of all the parallel platform mechanisms which consists of a top platform connected at three or four points to a planar base by six SPS legs. The number of the connection points at the base can be 3, 4, 5 or 6. Some of the new results which are first proposed in this paper are numerically verified.

A mapping which transforms the relative displacements of one object with respect to a reference object into image points has been developed by interpreting the relative displacement in terms of affine coordinates. The mapping provides a novel mathematical tool that solves interference problems of objects in three-dimensional space. By use of this mapping, the geometrical condition of interference of objects is represented by simple inequalities. The inverse mapping provides the means of avoiding interference and can be utilized for articulation of robot arms so as to avoid collision with obstacles.

This article introduces an invariant measure to quantify the motion of a rigid body attached to the end effector of a serial manipulator. The measure arises as a natural consequence of the properties of the Euclidean group. It is invariant with respect to the position and orientation of the fixed and moving coordinate systems used to parameterize the motion of the manipulator. It is independent of the type and number of joints in the chain and the dimensions used to parameterize the chain. The singularities of the manipulator are also predicted by the measure. Finally, it is shown that, when applied to redundant manipulators, the measure quantifies the importance of each joint of the manipulator.

Thorough theoretical investigations collaborate the experimental findings that in general stiffness matrices are asymmetric. This work details the results for the simplest types of compliant couplings that consist of translational springs acting in-parallel. The resulting stiffness matrices are global, which means that they are functions of the configuration of their respective compliant couplings. A new parameter ( ϱ = l 0 / l , ratio of unloaded to current spring length) is introduced for each translational spring, and the deviations of ϱ i from unity indicate how and when the stiffness matrix becomes asymmetric.

The principle of transference has been, since the last century, the center of many controversies. Despite its importance in the kinematic analysis of spatial mechanisms, and in instantaneous kinematics, no complete proof of the principle is currently available. This work presents a review of the history of the principle, then shows a clear statement of the principle, as well as a thorough proof.

This is the first of a series of papers dealing with the path planning for a spatial 4R robot with multiple spherical obstacles inside the workspace. In this paper, a time efficient algorithm has been developed to determine a collision free path for the end effector tip of the robot with a single spherical obstacle inside the workspace. A truncated pyramid and a right circular torus are used to model the nonreachable workspaces of the end effector tip of the robot. The problem of guiding the spatial 4R manipulator while avoiding a spherical obstacle is reduced to moving a point while avoiding a truncated pyramid and/or a right circular torus inside the workspace. The point represents the tip of the end effector of the manipulator. This approach produces an efficient algorithm for determining a collision free path. The algorithm has been successfully developed and implemented in the Silicon Graphics 4D-70GT workstation to verify the results.

This article presents a meaningful, practical, and theoretically sound solution that solves the problem of grasping a rigid object with a hand that has redundant (>6) grasping contacts. This is accomplished by introducing compliance at each contact point in such a way as to provide the engineer with the capabilities of object manipulation via controlled forces at the contact points. This method of solution is adapted straight-away to compute the static forces generated in the legs of a redundant in-parallel manipulator that equilibrates a wrench applied to the moving/platform or end-effector. In a way similar to the redundant grasping problem, this is accomplished by introducing the knowledge of the compliances that exist in the legs. The solution thus obtained stems from physical parameters that model the in-parallel manipulator. The in-depth study of the duality between the statics of in-parallel manipulators and the kinematics of serial manipulators reveals a meaningful, practical, and theoretically sound solution for the inverse kinematics of a redundant serial manipulator. This is accomplished by incorporating the knowledge of the compliances that exist or are desired to exist in the joints of the manipulator. (For instance, the torsional compliance in revolute joints or the linear compliance in prismatic joints.) Such information provides a physically meaningful model of the serial manipulator that in turn yields a physically meaningful set of joint increments for a given end-effector twist. © 1992 John Wiley & Sons, Inc.

A forward displacement analysis in closed-form is performed for each case of a class of Stewart Platform mechanisms. This class of mechanisms, which are classified into three cases, are called the “4-4 Stewart Platforms,” where each of the mechanisms has the distinguishing feature of six legs meeting either singly or pair-wise at four points in the top and base platforms. (This paper only addresses those 4-4 Platforms where both the top and base platforms are planar.) For each case, a polynomial is derived in the square of a tan-half-angle that measures the angle between two planar faces of a polyhedron embedded within the mechanism. The degrees of the polynomials for the first, second, and third cases are, respectively, eight, four, and twelve. All the solutions obtained from the forward displacement analyses for the three cases are verified numerically using a reverse displacement analysis.

In this paper, a complete invariant classification of three-systems is developed. The classification is based in the representation of screw systems as subspaces of the orthogonal space formed by all the infinitesimal screws. The symmetric bilinear forms associated with the orthogonal space, which are used in the classification, are the Killing, Klein and generalized Klein forms that were developed in a companion paper.

The classification of screw systems is systematically reformulated in terms of the theory of orthogonal spaces. The Lie algebra of the Euclidean group is isomorphic to the algebra of infinitesimal screws. The orthogonal space structure of the Lie algebra can thus be used for translating the theory of screw systems into a theory of subspaces of the Lie algebra of the Euclidean group. The reciprocal product, also known as the Klein form, is the leading criterion for the classification of screw systems. Furthermore, the Killing form provides a secondary criterion for a finer classification.

In this paper, a complete classification of one- and two-systems is developed. The classification is based on the representation of screw systems as subspaces of the orthogonal space formed by all the infinitesimal screws. It is proved that the two-systems classification is complete. The symmetric bilinear forms associated with the orthogonal space are the Killing, Klein and generalized Klein form as developed in a companion paper.

A reverse kinematic analysis is presented of a six-DOF subchain of a modified seven-DOF flight telerobotic servicer manipulator system. The six-DOF subchain is designated as a TR-RT chain, which describes the sequence of manipulator joints beginning with the first grounded hook joint (universal joint) T, where the sequence R-R designates a pair of revolute joints with parallel axes. At the outset, it had been thought that the reverse kinematic analysis would be similar to a TTT manipulator previously analyzed, in which the third and fourth joints intersected at a finite point. However, this is shown not the case, and a 16th-degree tan-half-angle polynomial is derived for the TR-RT manipulator.