This work aims to improve perceived safety and comfort of cyclists by proposing a topological optimization of existing cycling networks. We assign weights to a six-category system for bike lanes based on their segregation from motorized vehicles using the well-developed CycleRAP tool. Each bike lane is weighted based on its category and topological features. Graph theory metrics are then applied to analyze the core topological characteristics of cycling networks across various French municipalities. These metrics form the basis for estimating and predicting cyclists’ perceived safety and comfort levels, as reported in local surveys. Building on this relationship, we formulate a topology optimization problem aimed at maximizing predicted safety and comfort within budgetary constraints. To tackle this complex problem, we introduce a topological optimization algorithm and compare its performance with existing algorithms to ensure reliability. This approach integrates graph theory with real-world indicators, providing a comprehensive quantitative framework to support decision-making in urban planning and resource allocation.

This work focuses on evaluating the potential of variable speed limits (VSLs) in a synthetic urban network to improve both environmental sustainability and traffic performance. The traffic system is modeled using the microscopic traffic simulator SUMO, and a physical fuel consumption and NOx emission model is used to assess the vehicles’ energy efficiency. Speed limits are controlled through a nonlinear model predictive control (NMPC) approach, in which the traffic evolution and fuel consumption are respectively predicted with a macroscopic traffic model, namely the cell transmission model (CTM), and a pre-calibrated artificial neural network (ANN). The results reveal that in transient phases between different levels of congestion, the proposed eco-VSL controller is faster to decongest the network, resulting in an improvement of the environmental sustainability and the traffic performance both in the controlled network, and at its boundary roads.

In this paper, a new predictive approach is proposed for the impedance control of bilateral drive-by-wire teleoperation systems. The proposed control structure includes two mirror predictors/observers in both the master and slave sides. These predictors/observers are used to simultaneously estimate the master and slave internal dynamics, and thereby to avoid the use of the delayed transmitted information. As a consequence, the influence of the delay on the whole system can be minimized and the performance can be improved. Under a set of suited hypotheses, the proposed control structure is shown to be uniformly ultimate stable, even in the presence of time-varying delays. Simulation results are presented to show the effectiveness of the proposed approach. The behavior of the control structure is also experimentally demonstrated while performing remote steering of a small autonomous vehicle

We address the problem of energy optimal gait generation for biped robots. Using a simplified robot dynamics that ignores the effects of centripetal forces, we obtain unconstrained optimal trajectories generated by piecewise constant inputs. The study a complete gait cycle comprising single support, double support and the transition phases. The energy optimal gaits for different step lengths and velocities are compared with natural human gait.

The paper is devoted to the problem of nonlinear robust control design for underwater vehicle/manipulator (UVM) systems composed of a freefloating platform equipped with a robot manipulator. The different bandwidth characteristics of the composite vehicle/arm dynamics are used as a basis for the control design via singular perturbation theory. The main contribution of this paper is that a robust nonlinear control is only required in the slow-subsystem (vehicle dynamics). Thus, this control is only used to compensate the coupling effects from the arm to the base. The paper also presents a comparative study between simple PD, a partial linearized control and the nonlinear robust feedback.

One of the results of a research project on mechatronics is a mobile robot, which was used as a carrier for research on the design of mechatronical systems. This mobile robot, the Mobile Autonomous Robot Twente (MART), is intended to be used as major part of a future assembly factory. In this paper the implementation on the MART-robot of a hybrid controller for stabilization of non-holonomic systems is described. Limitations of the physical model of the mechanical structure of the MART-robot lead to a number of practical problems. An interesting result given in the paper is the insight obtained into the geometrical meaning of different parameters of the controller, which allowed considerable improvements in the performance of the controller on the actual mobile robot.>

This paper investigates the benefits of applying simple PID+nonlinear controller to subsea robot. This control structure has the advantage of only adding a supplementary nonlinear feedback loop to the existing linear PID-regulator and at the same time improving both the transient and stability margins. Several simulations and experiments have been performed on the experimental subsea robot (VORTEX) and have demonstrated the improvements of the PID+nonlinear controller over the simple PID.>

This paper presents a feedback nonlinear control law for a train-like vehicle (TLV) used in nuclear power-station maintenance. The front cart is either manual or automated guided. The rear carts are feedback controlled. The control objective is to ensure that the rear carts track the path produced (online) by the front cart. This controller was experimentally tested on the TLV-prototype.>

A piecewise smooth feedback control law for path following for the kinematic model of a nonholonomic mobile robot is proposed. The resulting motion can consist of stopping and reversing phases. The desired path is supposed to be composed of straight lines and arcs of circles joined at intermediate configurations. The proposed feedback control law yields exponential convergence to configurations representing stopping phases and to the terminal configuration.>

The authors present an exponentially stable controller for a two-degree-of-freedom robot with nonholonomic constraints. Although this system is controllable, it has been shown to be nonstabilizable via smooth state feedback. A particular class of piecewise continuous controller which exponentially stabilizes the robot about the origin was previously proposed by the authors (1991). This approach is extended to stabilize about an arbitrary position and orientation, and to track a sequence of points. This feedback law is naturally combined with path planning when the desired path to be followed can be composed of a sequence of straight lines and circle segments, i.e. shortest paths of bounded curvature in the plane.>

High-precision measurements of joint displacements are available on robot manipulators. In contrast, velocity measurements obtained through tachometers are, in many cases, contaminated by noise. It is therefore economically and technically interesting to investigate the possibility of controlling robot dynamics by only using angular position measurements. Two alternative approaches for trajectory tracking control via nonlinear estimated state feedback are presented. The first scheme is based on smooth functions, whereas the second uses switching gains. The stability of the closed-loop system is investigated. Both approaches yield exponentially stable closed-loop systems. The local attraction areas are characterized in terms of controller and observer gains, initial state values, and robot model parameters.>

Examples are given that modify some oversimplified statements usually made about the motion of robots in singular configurations. A robot may be controlled in an arbitrary direction from a singular configuration if the velocity profiles are shaped in a proper way. The observations on possible motions open a number of questions, since a wider class of motions is possible that at first sight. Hence, the results are of relevance to path programming, to path following, and to controller design.>

The authors consider the problem of improving the parameter identifiability properties of a robot model and derive a sequential estimation algorithm which substantially simplifies the estimating procedure. The estimation of the invariants (masses, inertias, etc.), which usually requires at most 11n parameters for a robot manipulator with n degrees of freedom, can be performed link by link in a sequential manner by n algorithms of size n/sub i/, where Sigma n/sub i/ is smaller than 11n. Optimization of the robot trajectories seeking to improve parameter identifiability can be simplified. This method enhances the numerical algorithm conditioning and facilitates the selection of a high excited identification sequence, improving the parameter identifiability. The convergence of the estimates to their true values can be obtained provided that the information vector associated with each link is persistently exciting.>

An approach for designing robust controllers via state-space feedback is presented. The robot model parameters are assumed to be unknown and velocity measurements are assumed to be unavailable. State observation and parameter adaptation are performed simultaneously. The adaptation law, the observer gains and the control law are designed on the reduced-order manifold which results from the invariance of the switching surface. With respect to the authors' previous work, the asymptotic stability of the closed-loop system resulting from the approach presented is not conditioned by a particular type of inertia matrix variations. On the other hand, the introduction of an adaptation loop may also be motivated by a reduction of chattering at control law level since the control law only depends on the estimated state and parameter vectors, and hence contains no terms proportional to discontinuities.>

The problem of controlling a two-degree of freedom wheeled mobile robot (2-DOF WMR) under path and input torque constraints is examined. Path constraints are imposed by the task to be performed while input torque constraints are due to power limitations in the motor actuators. A dynamic control design based on a two-dimensional WMR model (tangential navigation velocity and orientation) and on recent results concerning online reference profile generation obtained by O. Dahl and L. Nielsen (1989) is proposed. The capabilities of this method are investigated through simulations and experiments performed on the micro-WMR KITBORG.>

A new control scheme is presented which makes the closed-loop system properties robust under the eventuality of inexact friction compensation which may provoke limit cycles. This control design has the advantage that the possible oscillations can be reduced in amplitude and modified in frequency independently of the closed-loop system specifications. Also proposed is an approximate Tustin model, as a basis for the friction compensation, obtained by including a priori information about the lubricant coefficients. Simulations have shown that this model gives better accuracy than other models and that, together with the robust linear compensator, it improves adaptive transients.>

The problem of modeling and compensation of friction velocities close to zero is analyzed. A model, linear in parameters, which captures the downward bends at low velocity is used to adaptively compensate for friction. The need for this type of model is mainly motivated by instability phenomena that can be caused by overcompensation when simple models (such as Coulomb friction models) are used as a basis for the friction compensation. This model, in combination with an adaptive computed torque method, is tested experimentally in the last link of a robot manipulator. The prediction error e/sub k/, which directly gives the accuracy of the predicted friction, remains within the preestablished threshold of +or-0.8 Nm. The experiments were realized using an IBM PC-compatible computer, leading to a sampling time of 13 ms.>

A decentralized control design is presented for industrial robots with flexibilities at the joints. Based on an independent joint robot model, a two-degree-of-freedom, linear compensator is proposed. The latter is designed based on the Youla parametrization yielding a stable compensator which effectively takes into account the oscillatory modes, and uses only measurable actuator signals (motor shaft position). Conditions for achieving global stability are given. A two-step estimation mechanism is applied for estimating the complete robot arm model's parameters.>

A control scheme is proposed where the nonlinear effects of friction are compensated adaptively. When the friction is compensated, the motor drive can approximately be described by a constant coefficient linear model. Standard methods can be applied to design a regulator for such a model. This results in a control law which is a combination of a fixed linear controller and an adaptive part which compensates for nonlinear friction effects. Experiments have clearly shown that both static and dynamic friction have nonsymmetric characteristics. They depend on the direction of motion. This is considered in the design of the adaptive friction compensation. The proposes scheme has been implemented and tested on a laboratory prototype with good results. The control law is implemented on an IBM PC. The ideas, algorithm, and experimental results are described. The results are relevant for many precision drives, such as those found in industrial robots.

This paper proposes a control scheme where the nonlinear effects of friction are compensated adaptively. When the friction is compensated the motor drive can approximately be described by a constant coefficient linear model. Standard methods can be applied to design a regulator for such a model. This results in a control law which is a combination of a fixed linear controller and an adaptive part which compensates for nonlinear friction effects. Experiments have clearly shown that both static and dynamic friction have nonsymmetric characteristic. They depend on the direction of motion. This is considered in the design of the adaptive friction compensation. The proposed scheme has been implemented and tested on a laboratory prototype with good results. The control low is implemented on an IBM-PC. The paper describes the ideas, the algorithm and the experimental results. The results are relevant for many precision drives like those found in industrial robots.