Showing papers in "The International Journal of Robotics Research in 1998"
TL;DR: This paper presents a method for robot motion planning in dynamic environments that consists of selecting avoidance maneuvers to avoid static and moving obstacles in the velocity space, based on the rental positions and velocities of the robot and obstacles.
Abstract: This paper presents a method for robot motion planning in dynamic environments. It consists of selecting avoidance maneuvers to avoid static and moving obstacles in the velocity space, based on the cur rent positions and velocities of the robot and obstacles. It is a first- order method, since it does not integrate velocities to yield positions as functions of time.The avoidance maneuvers are generated by selecting robot ve locities outside of the velocity obstacles, which represent the set of robot velocities that would result in a collision with a given obstacle that moves at a given velocity, at some future time. To ensure that the avoidance maneuver is dynamically feasible, the set of avoidance velocities is intersected with the set of admissible velocities, defined by the robot's acceleration constraints. Computing new avoidance maneuvers at regular time intervals accounts for general obstacle trajectories.The trajectory from start to goal is computed by searching a tree of feasible avoidance maneuve...
1,555 citations
TL;DR: An integrated architecture that allows a mobile robot to plan its tasks—taking into account temporal and domain constraints, to perform corresponding actions and to con trol their execution in real-time—while being reactive to possible events is described.
Abstract: An autonomous robot offers a challenging and ideal field for the study of intelligent architectures. Autonomy within a rational be havior could be evaluated by the robot's effectiveness and robust ness in carrying out tasks in different and ill-known environments. It raises major requirements on the control architecture. Further more, a robot as a programmable machine brings up other archi tectural needs, such as the ease and quality of its specification and programming.This article describes an integrated architecture that allows a mobile robot to plan its tasks—taking into account temporal and domain constraints, to perform corresponding actions and to con trol their execution in real-time—while being reactive to possible events. The general architecture is composed of three levels: a de cision level, an execution level, and a functional level. The latter is composed of modules that embed the functions achieving sensor- data processing and effector control. The decision level is goal and event driven, a...
599 citations
TL;DR: A novel graphical technique based on the first return map that compactly captures the entire evolution of the gait, from symmetry to chaos, of a biped robot on inclined slopes.
Abstract: The focus of this work is a systematic study of the passive gait of a compass-like, planar, biped robot on inclined slopes. The robot is kinematically equivalent to a double pendulum, possessing two kneeless legs with point masses and a third point mass at the "hip" joint. Three parameters, namely, the ground-slope angle and the normalized mass and length of the robot describe its gait. We show that in response to a continuous change in any one of its parame ters, the symmetric and steady stable gait of the unpowered robot gradually evolves through a regime of bifurcations characterized by progressively complicated asymmetric gaits, eventually arriving at an apparently chaotic gait where no two steps are identical. The robot can maintain this gait indefinitely.A necessary (but not sufficient) condition for the stability of such gaits is the contraction of the "phase-fluid" volume. For this frictionless robot, the volume contraction, which we compute, is caused by the dissipative effects of the ground-impa...
557 citations
TL;DR: This paper considers in detail the case of "undulatory locomotion" in which net motion is generated by coupling internal shape changes with external nonholonomic con straints and uses geometric methods to study basic problems in the mechanics and control of locomotion.
Abstract: This paper uses geometric methods to study basic problems in the mechanics and control of locomotion. The authors consider in detail the case of undulatory locomotion in which net motion is generated by coupling internal shape changes with external nonholonomic constraints. Such locomotion problems have a natural geometric interpretation as a connection on a principal fiber bundle. The properties of connections lead to simplified results for studying both dynamics and issues of controllability for locomotion systems. The authors demonstrate the utility of this approach using a novel snakeboard and a multisegmented serpentine robot that is modeled after Hirose`s active cord mechanism.
322 citations
TL;DR: An environment for the design, simulation, and control of Internet-based force-reflecting telerobotic systems as using a segment of the computer network to connect the master to the slave is described.
Abstract: This paper describes an environment for the design, simulation and control of Internet-based force-relflecting telerobotc systems. We define these systems as using a segment of the computer network to connect the master to the slave.
222 citations
TL;DR: This paper suggests a Kalman-filter approach to the estimation of angular velocity and acceleration from (quantized) shaft-encoder measurements, and investigates Kalman filtering with constant sampling rate, and also with measurements triggered by encoder pulses.
Abstract: This paper suggests a Kalman-filter approach to the estimation of angular velocity and acceleration from (quantized) shaft-encoder measurements Finite-difference estimates deteriorate as sampling rates are increased For small sampling periods, we show that the filtering problem is the dual of the cheap control problem, and we jus tify the use of all-integrator models We investigate Kalman filtering with constant sampling rate, and also with measurements triggered by encoder pulses Simulation and experimental results are given
208 citations
TL;DR: This approach treats the base nonholonomy and the kinematic redundancy in a unified manner to formulate new task constraints and makes it particularly suitable for real-time implementation.
Abstract: This paper presents a simple on-line approach for motion control of mobile manipulators comprising a manipulator arm mounted on a mobile base. The proposed approach is equally applicable to nonholonomic mobile robots such as rover-mounted manipulators and holonomic mobile robots such as tracked robots and compound manipulators. For wheeled mobile robots, the nonholonomic base constraints are incorporated directly into the task formulation as kinematic constraints. The configuration control approach is ex tended to exploit the redundancy introduced by the base mobility to perform a set of user-specified additional tasks during the end- effector motion while satisfying the nonholonomic base constraints (if applicable). This approach treats the base nonholonomy and the kinematic redundancy in a unified manner to formulate new task constraints. The computational efficiency of the proposed control scheme makes it particularly suitable for real-time implementation. Two simulation studies are presented to demons...
202 citations
TL;DR: A simple method based on the virtual work principle is proposed for modeling parallel robots, leading to a very efficient model that has been implemented in a real-time computed-torque control algorithm.
Abstract: In recent years, increased interest in parallel robots has been ob served. Their control with modern theory, such as the computed- torque method, has, however, been restrained, essentially due to the difficulty in establishing a simple dynamic model that can be calcu lated in real time. In this paper, a simple method based on the virtual work principle is proposed for modeling parallel robots. The mass matrix of the robot, needed for decoupling control strategies, does not explicitly appear in the formulation; however, it can be computed separately, based on kinetic energy considerations. The method is applied to the DELTA parallel robot, leading to a very efficient model that has been implemented in a real-time computed-torque control algorithm.
194 citations
TL;DR: This paper argues that there exists a natural partitioning between information and energy wherein in formation is conveyed at frequencies above roughly 30 Hz, while the energetic interaction between the slave and the environment takes place at frequencies below this.
Abstract: The quality of telepresence provided by a force-reflecting teleopera tor is determined, for the most part, by the fidelity of the contact-force information fed back to the operator. These fed-back forces, how ever, also directly influence system stability, and in this paper we investigate the relationship between fidelity and stability with a view toward understanding how stability considerations impose funda mental limits on system performance. The key idea of our work is to draw an explicit distinction between the information conveyed by the force signal and the energy inherent in that signal. Using known physiological properties of the operator, we argue that there exists a natural partitioning between information and energy wherein in formation is conveyed at frequencies above roughly 30 Hz, while the energetic interaction between the slave and the environment takes place at frequencies below this. We embody this distinction in a two-channel framework that we claim provides insight into the de sign of force-reflecting systems. Using a 1-DOF model, we study the effect of various system characteristics, notably mass, stiffness, and damping properties, on performance and stability. This model is used to derive expressions for the maximum force-reflection ratio that guarantees stability against pure-stiffness environments and to investigate the role of various compensation elements, including lo cal force control around the slave. Finally, a framework is developed for force-reflecting teleoperation that maximizes the force informa tion conveyed to the operator, subject to the constraints imposed by stability considerations.
189 citations
TL;DR: TangentBug as discussed by the authors uses the range data to compute a locally short-est path, based on a novel structure termed the local tangent graph (LTG), and the robot uses the LTG for choosing the locally optimal di rection while moving toward the target, and for making local short-cuts and testing a leaving condition while moving along an obstacle boundary.
Abstract: The Bug family algorithms navigate a 2-DOF mobile robot in a completely unknown environment using sensors. TangentBug is a new algorithm in this family, specifically designed for using a range sensor. TangentBug uses the range data to compute a locally short est path, based on a novel structure termed the local tangent graph (LTG). The robot uses the LTG for choosing the locally optimal di rection while moving toward the target, and for making local short- cuts and testing a leaving condition while moving along an obstacle boundary. The transition between these two modes of motion is governed by a globally convergent criterion, which is based on the distance of the robot from the target. We analyze the properties of TangentBug, and present simulation results that show that Tangent Bug consistently performs better than the classical Bug algorithms. The simulation results also show that TangentBug produces paths that in simple environments approach the globally optimal path, as the sensor's maximal detectio...
170 citations
TL;DR: This paper applies the multilevel scheme to carlike robots pulling trail ers, that is, tractor-trailer robots, and shows that using the multi-level scheme leads to significantly better performance than direct transformations to feasible paths.
Abstract: We present a new and complete multilevel approachfor solving path- planning problems for nonholonomic robots. At the first level, a path is found that disrespects (some of) the nonholonomic constraints. At each of the next levels, a new path is generated by transformation of the path generated at the previous level. The transformation is such that more nonholonomic constraints are respected than at the previous level. At the final level, all nonholonomic constraints are respected.We present two techniques for these transformations. The first, which we call the pick and link technique, repeatedly picks pieces from the given path, and tries to replace them by more feasible ones. The second technique restricts the free configuration space to a "tube" around the given path, and a road map that captures the free-space connectivity within this tube is constructed by the prob abilistic path planner. From this road map we retrieve a new, more feasible path.In the intermediate levels, we plan paths for what we ref...
TL;DR: The authors define local maximum sets of tendons that are redundant simultaneously (local maximum redundant tendon sets) and obtain an irreducible description of a redundant tendon in terms of the others.
Abstract: In this paper, several basic issues are discussed regarding tendon redundancy and joint stiffness adjustability for a robotic mechanism driven with redundant tendons. After briefly discussing tendon- controllability, the authors define local maximum sets of tendons that are redundant simultaneously (local maximum redundant tendon sets) and obtain an irreducible description of a redundant tendon in terms of the others. The authors obtain conditions under which the joint stiffness is adjustable using the tendons' nonlinear elasticity.
TL;DR: An implemented pose planner is described, which uses an analysis of the mechanics of pushing an object to generate open-loop plans that do not require sensing and is proven to be com plete and to have polynomial time complexity.
Abstract: This paper studies the use of pushing actions to orient and trans late objects in the plane. The authors use linear normal pushes, which are straight-line pushes in a direction normal to the pushing fence. These pushes are specified by the fence orientation and push distance. The authors show that a set of linear normal pushes can always be found to move any polygonal object from any initial con figuration to any goal configuration in the obstacle-free plane. The object configuration is specified by its pose; that is, its position and orientation. The authors formulate the search for such a sequence of pushes as a linear programming problem. They then describe an implemented pose planner that uses this formulation to identify a sequence of linear normal pushes given any polygonal object, any initial pose, and any goal pose. This planner is proven to be com plete and to have polynomial time complexity. The planner, which uses an analysis of the mechanics of pushing an object, generates open-loop plans that...
TL;DR: The ORCCAD programming environment for robotic systems allows users to address automatic control laws in continuous time at the lower levels, and aspects of discrete-time logic at the higher levels, through tools of specification, formal verification, simulation, and real-time code generation integrated within a set of dedicated graphical interfaces.
Abstract: The ORCCAD programming environment for robotic systems allows users to address automatic control laws in continuous time at the lower levels, and aspects of discrete-time logic at the higher lev els. ORCCAD provides tools of specification, formal verification, simulation, and real-time code generation integrated within a set of dedicated graphical interfaces. Basic robot actions, which are in trinsically hybrid entities, are handled by the ROBOT-TASK struc ture, which smartly interfaces aspects of continuous and discrete time. ROBOT-TASKS are further logically composed into more complex actions, ROBOT-PROCEDURES, through a dedicated lan guage. While system performance can be checked using simula tions, crucial properties such as deadlock avoidance, safety, and liveness can be formally verified at both levels. The approach is illustrated with an underwater inspection mission.
TL;DR: This paper considers how to enumerate the nonisomor phic (or geometrically unique) assembly configurations of a modular robotic system and proposes an enumeration algorithm to generate nonisomorphic assembly config urations based on this equivalence relation.
Abstract: A modular robotic system consists of standardized joint and link units that can be assembled into a number of different kinematic configurations to meet various task requirements. Owing to typical symmetries in module design, different assembly configurations may lead to robotic structures that are geometrically identical, or isomorphic. This paper focuses on the problem of enumerating the set of kinematically distinct modular robot assembly configurations from a given set of modules. The authors first consider how to enumerate the nonisomorphic (or geometrically unique) assembly configurations of a modular robotic system. The scheme is based on a novel representation of a modular robot assembly configuration as an assembly incidence matrix (AIM). Equivalence relations based on symmetries in module geometry and graph isomorphisms are defined on the AIMs. An enumeration algorithm to generate nonisomorphic assembly configurations based on this equivalence relation is proposed. They then present an algorithm to identify the kinematically equivalent robots. The application of these two algorithms will result in the set of kinematically unique assembly configurations. Examples demonstrate that this method is a significant improvement over a brute-force enumeration process.
TL;DR: A process monitor for robotic assembly based on hidden Markov models (HMMs) is presented, which allows for dynamic motions of the workpiece, accounts for sensor noise and friction, and exploits the fact that the amount of force information is large when there is a sudden change of discrete state in robotic assembly.
Abstract: A process monitor for robotic assembly based on hidden Markov models (HMMs) is presented. The HMM process monitor is based on the dynamic force/torque signals arising from interaction be tween the workpiece and the environment. The HMMs represent a stochastic, knowledge-based system in which the models are trained off-line with the Baum-Welch reestimation algorithm. The assem bly task is modeled as a discrete event dynamic system in which a discrete event is defined as a change in contact state between the workpiece and the environment. Our method (1) allows for dynamic motions of the workpiece, (2) accounts for sensor noise andfriction, and (3) exploits the fact that the amount of force information is large when there is a sudden change of discrete state in robotic assembly. After the HMMs have been trained, the authors use them on-line in a 2D experimental setup to recognize discrete events as they occur. Successful event recognition with an accuracy as high as 97% was achieved in 0.5-0.6 s with a train...
TL;DR: The results indicate that body inertia is a critical design parameter for running robots, and suggest passive mechanisms for balance and gait transition in legged robots and animals.
Abstract: In this paper, a 2-DOF model for quadrupedal running-in-place is presented, consisting of a rigid body on springy legs. "Energy- pumping " feedback is included to excite the natural dynamics of the system. The model exhibits at least two periodic solutions, which correspond to the bound and pronk gaits of four-legged animals. Approximate return maps are constructed around both trajectories, and these are used to derive explicit expressions for the amplitude and stability of the gaits. The pronk is shown to produce significantly more height than the bound for the same amount of effort. However, the bound has more desirable stability characteristics: simulations and analysis demonstrate that the bound is unstable if a dimension less body inertia is greater than 1, which is an unlikely situation for either a robot or an animal. The pronk's stability, however, exhibits coupling between height and inertia: a given inertia is more likely to cause instability for large heights than for small heights. These resul...
TL;DR: This paper discusses a method for representing these primitive operations of holding or rotating the part in an equilibrium grasp, allowing the part to fall in disequilibrium, and sliding one hand or the other relative to the part.
Abstract: When two hands manipulate a part, they perform three basic opera tions : holding or rotating the part in an equilibrium grasp, allowing the part to fall in disequilibrium, and sliding one hand or t...
TL;DR: This paper addresses the problem of controlling positions and forces of multiple redundant manipulators cooperatively handling an ob ject in a decentralized manner while optimizing a performance in dex by proposing one adaptive and two nonadaptive de centralized controllers.
Abstract: This paper addresses the problem of controlling positions and forces of multiple redundant manipulators cooperatively handling an ob ject in a decentralized manner while optimizing a performance in...
TL;DR: This paper discusses the modeling and control of a spatial mobile manipulator that consists of a robotic manipulator mounted on a wheeled mobile platform and a nonlinear interaction-control algorithm, developed and applied to coordinate the two sub systems' controllers.
Abstract: This paper discusses the modeling and control of a spatial mobile manipulator that consists of a robotic manipulator mounted on a wheeled mobile platform. The Lagrange-d'Alembert formulation is used to obtain a concise description of the dynamics of the system, which is subject to nonholonomic constraints. The complexity of the model is increased by introducing kinematic redundancy, which is created when a multilinked manipulator is used. The kinematic redundancy is resolved by decomposing the mobile manipulator into two subsystems: the mobile platform and the manipulator. The re dundancy resolution scheme employs a nonlinear interaction-control algorithm, which is developed and applied to coordinate the two sub systems' controllers. The subsystem controllers are independently designed, based on each subsystem's dynamic characteristics. Sim ulation results show the promise of the developed algorithm.
TL;DR: An approach to the planning of optimal robotic motions in the preparation of obstacles based on the use of nonclassical formulation of Pontryagin's maximum principle, which makes it possible to handle efficiently the state constraints resulting from the robotic tasks to be performed.
Abstract: An approach to the planning of optimal robotic motions in the pres ence of obstacles is proposed. It is based on the use of nonclassical formulation of Pontryagin's maximum principle, which makes it possible to handle efficiently the state constraints resulting from the robotic tasks to be performed. The convergence properties of the algorithm are examined. A computer example involving a pla nar redundant manipulator of three revolute kinematic pairs, which performs two tasks in a two-dimensional work space including ob stacles, is given. A comparison of the proposed approach with the well-known method of penalty function is made.
TL;DR: The quality index λ, 0 ≤ λ ≤ 1, is a constructive measure of acceptable design proportions and should be tested for quality against the authors' 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.
Abstract: 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 uncontro...
TL;DR: In this paper, two versions of strictly convex cost functions, one of them self-concordant, are considered and it is shown that the proposed algo rithms guarantee convergence to the unique solution of the semidefinite programming problem associated with dextrous grasping force optimization.
Abstract: One of the central issues in dextrous robotic hand grasping is to balance external forces acting on the object and at the same time achieve grasp stability and minimum grasping effort. A companion paper shows that the nonlinear friction-force limit constraints on grasping forces are equivalent to the positive definiteness of a certain matrix subject to linear constraints. Further, compensation of the external object force is also a linear constraint on this matrix. Consequently, the task of grasping force optimization can be formulated as a problem with semidefinite constraints. In this paper, two versions of strictly convex cost functions, one of them self-concordant, are considered. These are twice-continuously differentiable functions that tend to infinity at the boundary of possible definiteness. For the general class of such cost functions, Dikin-type algorithms are presented. It is shown that the proposed algorithms guarantee convergence to the unique solution of the semidefinite programming problem associated with dextrous grasping force optimization. Numerical examples demonstrate the simplicity of implementation, the good numerical properties, and the optimality of the approach.
TL;DR: The problem of energy-efficient control of running legged mecha nisms is addressed via the case study of the planar one-legged hopper, and the basis of a method for the derivation of a new class of simple controllers capable of stabilizing passive periodic motions is set.
Abstract: The problem of energy-efficient control of running legged mecha nisms is addressed via the case study of the planar one-legged hopper. Owing to its mechanical simplicity, the planar one-legged hopper is generally considered as the basic prototype of mechanisms capable of ballistic running gaits. What makes this system particularly inter esting is that when properly endowed with energy-storing springs, it can be controlled without spending much energy for actuation. This possibility has already been investigated in a few studies, but has not yet been sufficiently explored. The present study is an at tempt in this direction. Being primarily motivated by control-design and analysis aspects, we have tried to set the basis of a methodol ogy for the derivation of a new class of simple controllers capable of stabilizing passive periodic motions. Elements of this class are derived by making specific novel choices for the model used for con trol design and the control actuation setting. Impulsive feedback inputs a...
TL;DR: The issues of evaluating high-level robot programming toolsets as to their usability are examined, including how usability criteria are established and target values are chosen.
Abstract: The days of specifying missions for mobile robots using traditional programming languages such as C++ and LISP are coming to an end. The need to support operators lacking programming skills coupled with the increasing diversity of robot run-time operating systems is moving the field toward high-level robot programming toolsets that allow graphical mission specification. This paper ex plores the issues of evaluating such toolsets as to their usability. We first examine how usability criteria are established and perfor mance target values are chosen. The methods by which suitable experiments are created to gather data relevant to the usability criteria are then presented. Finally, methods to analyze the data gathered to establish values for the usability criteria are discussed. The MissionLab toolset is used as a concrete example throughout the article to ground the discussions, but the methods and techniques are generalizable to many such systems.
TL;DR: The authors have developed a framework for determining feedback strategies by blending ideas from stochastic optimal control and dynamic game theory with traditional preimage planning concepts, which generalizes classical preimages to performance preimages and pre image planning for de signing motion strategies with information feedback.
Abstract: The authors consider the problem of determining robot motion plans under sensing and control uncertainties. Traditional approaches are often based on methodology known as preimage planning, which involves worst-case analysis. The authors have developed a gen eral framework for determining feedback strategies by blending ideas from stochastic optimal control and dynamic game theory with traditional preimage planning concepts. This generalizes classical preimages to performance preimages and preimage planning for de signing motion strategies with information feedback. For a given problem, one can define a performance criterion that evaluates any executed trajectory of the robot. The authors present methods for selecting a motion strategy that optimizes this criterion under either nondeterministic uncertainty (resulting in worst-case analysis) or probabilistic uncertainty (resulting in expected-case analysis). The authors present dynamic programming-based algorithms that nu merically compute performance prei...
TL;DR: An iterative learning-control law is proposed for impedance control of robotic manipulators and the robustness of the learning impedance-control system to the fluc tuation of the dynamics, output measurement noise, and error in the initial conditions is analyzed.
Abstract: In this paper, an iterative learning-control law is proposed for impedance control of robotic manipulators. In most of the learning-controller designs in the literature, a reference trajectory is given and a learning algorithm is designed to force the trajectory tracking error to converge to zero as the action is repeated. In contrast, the authors` approach allows the performance of the learning system to be specified by a target impedance. A design method for analyzing the learning-impedance system is developed, and sufficient conditions for guaranteeing the convergence of the error to zero are derived. The robustness of the learning impedance-control system to the fluctuation of the dynamics, output measurement noise, and error in the initial conditions is also analyzed in details. Experimental results on a system using an industrial robot (SEIKO TT3300) are presented to illustrate the theoretical results.
TL;DR: This paper extends the paradigm to manipulation-planning problem, where the goal is to plan the motion of a robot so that it can move a given object from an initial configuration to a final configuration while avoiding collisions with the static obstacles and other movable objects in the environment.
Abstract: An emerging paradigm in solving the classical motion- planning problem (among static obstacles) is to capture the connectivity of the configuration space using a finite (but pos sibly large) set of...
TL;DR: The pheromone-oriented behavior of moths will be demonstrated by synthesis with biosensors and a small mobile robot that is controlled by recurrent neural networks and is therefore a new type of robot.
Abstract: In this paper, the pheromone-oriented behavior of moths will be demonstrated by synthesis with biosensors and a small mobile robot that is controlled by recurrent neural networks. Since antennae on...
TL;DR: This paper walks through the methodology and application of ControlShell, the component-based real-time programming system, and examines the application of this frame work to a dual-arm robotic work cell, a subsystem of the Space Shuttle Launch Processing System, and an underwater autonomous vehicle.
Abstract: Real-time system software is notoriously complex. Large projects must balance the special needs of real-time software—such as clock management, control systems, and strategy—with the needs of in teracting teams of programmers, managers, and long-term main tenance personnel. Successful projects require a solid software architecture, an intuitive graphical programming paradigm, a well- developed reuse system, and powerful system services.This paper walks through the methodology and application of ControlShell, the component-based real-time programming system. ControlShell provides an integrated development environment for building complex electromechanical systems. It targets complex systems that require both cyclic data processing and strategic event management and sequencing.ControlShell is specifically designed to facilitate team develop ment of complex electromechanical systems. Teams must share and reuse code; ControlShell provides component-level code shar ing and reuse. Complex systems require flexib...