Path Tracking Task Research Articles

2P1-F09 冗長性を利用した高速な軌跡追従手先定速作業の探索手法切換を用いた動作計画

We propose a motion planning method for fast motion of path tracking task with constant hand speed using redundancy of manipulator. The propose method is method that has improved previous method. We previously proposed a motion planning method that performs path finding on a parameter space of redundancy instead of motion planning. The hand path was segmented to difficult sections that are difficult to track with fast hand speed and easy sections that are easy to track fast hand speed, and path-finding was performed different path-finding method on each section in previous method. However, the previous method has a problem because path-finding methods that perform on each sections are fixed. In this paper, we propose a motion planning method switching path-finding method depending on results of path-finding on each sections. The propose method is validated by simulation of 3-link planar redundant manipulator.

Dynamic design, numerical solution and effective verification of acceleration-level obstacle-avoidance scheme for robot manipulators

For avoiding obstacles and joint physical constraints of robot manipulators, this paper proposes and investigates a novel obstacle avoidance scheme (termed the acceleration-level obstacle-avoidance scheme). The scheme is based on a new obstacle-avoidance criterion that is designed by using the gradient neural network approach for the first time. In addition, joint physical constraints such as joint-angle limits, joint-velocity limits and joint-acceleration limits are incorporated into such a scheme, which is further reformulated as a quadratic programming (QP). Two important ‘bridge’ theorems are established so that such a QP can be converted equivalently to a linear variational inequality and then equivalently to a piecewise-linear projection equation (PLPE). A numerical algorithm based on a PLPE is thus developed and applied for an online solution of the resultant QP. Four path-tracking tasks based on the PA10 robot in the presence of point and window-shaped obstacles demonstrate and verify the effectiveness and accuracy of the acceleration-level obstacle-avoidance scheme. Besides, the comparisons between the non-obstacle-avoidance and obstacle-avoidance results further validate the superiority of the proposed scheme.

The link and comparison between velocity-level and acceleration-level repetitive motion planning schemes verified via PA10 robot arm

To solve the joint-angle drift problem of redundant robot arms, this paper presents two kinds of repetitive motion planning (RMP) schemes (i.e., the velocity-level RMP scheme and the acceleration-level RMP scheme). Such two kinds of different-level RMP schemes can be reformulated as quadratic programming (QP) problems subject to equality and bound constraints. In addition, since the two kinds of RMP schemes solve the joint-angle drift problem at different levels, the link and comparison between the velocity-level and the acceleration-level RMP schemes are investigated in this paper. In order to compare the two kinds of RMP schemes, PA10 robot arm is tested to perform two different types of path-tracking tasks (i.e., the triangular path and the rhombic path) by employing velocity-level and acceleration-level RMP schemes. Computer-simulation results demonstrate the superiority of the acceleration-level RMP scheme, as compared with the velocity-level RMP scheme.

Vision Sensor-Based Driving Algorithm for Indoor Automatic Guided Vehicles

In this paper, we describe a vision sensor-based driving algorithm for indoor automatic guided vehicles (AGVs) that facilitates a path tracking task using two mono cameras for navigation. One camera is mounted on vehicle to observe the environment and to detect markers in front of the vehicle. The other camera is attached so the view is perpendicular to the floor, which compensates for the distance between the wheels and markers. The angle and distance from the center of the two wheels to the center of marker are also obtained using these two cameras. We propose five movement patterns for AGVs to guarantee smooth performance during path tracking: starting, moving straight, pre-turning, left/right turning, and stopping. This driving algorithm based on two vision sensors gives greater flexibility to AGVs, including easy layout change, autonomy, and even economy. The algorithm was validated in an experiment using a two-wheeled mobile robot.

Different-Level Simultaneous Minimization of Joint-Velocity and Joint-Torque for Redundant Robot Manipulators

In J Robot Syst 13(3):177---185 (1996), Ma proposed an efficient technique to stabilize local torque optimization solution of redundant manipulators, which prevents occurrence of high joint-velocity and guarantees the final joint-velocity to be near zero. To prevent the same problems, a different-level simultaneous minimization scheme is proposed in this paper for robotic redundancy resolution, which combines the minimum two-norm joint-velocity and joint-torque solutions via two weighting factors. Physical constraints such as joint-angle limits, joint-velocity limits and joint-acceleration limits are also taken into consideration in such a scheme-formulation. Moreover, the proposed different-level simultaneous minimization scheme is resolved at the joint-acceleration level and reformulated as a general quadratic program (QP). Computer-simulation results based on the PUMA560 robot manipulator performing different types of end-effector path-tracking tasks demonstrate the validity and advantage of the proposed different-level simultaneous minimization scheme. Furthermore, experimental verification conducted on a practical six-link planar robot manipulator substantiates the effectiveness and the physical realizability of the proposed scheme.

Path-Tracking Maneuvers With Industrial Robot Manipulators Using Uncalibrated Vision and Impedance Control

This paper presents an interaction control strategy for industrial robot manipulators which consists of the combination of a calibration-free, vision-based control method with an impedance-control approach. The vision-based, robot control method known as camera-space manipulation is used to generate a given, previously defined trajectory over an arbitrary surface. Then, a kinematic impedance controller is implemented in order to regulate the interaction forces generated by the contact between the robot end-effector and the work surface where the trajectory is traced. The paper presents experimental evidence on how the vision-force sensory fusion is applied to a path-tracking task, using a Fanuc M16-iB industrial robot equipped with a force/torque sensor at the wrist. In this task, several levels of interaction force between the robot end-effector and the surface were defined. As discussed in the paper, such a synergy between the control schemes is seen as a viable alternative for performing industrial maneuvers that require force modulation between the tool held by the robot and the working surface.

Acceleration-level repetitive motion planning of redundant planar robots solved by a simplified LVI-based primal-dual neural network

In this paper, we propose a novel repetitive motion planning (RMP) scheme at the joint-acceleration level (termed, the acceleration-level RMP scheme, the ARMP scheme), which incorporates joint-angle limits, joint-velocity limits and joint-acceleration limits. To do this, Zhang et al's neural-dynamic method is employed to derive and design such an ARMP scheme. Such a scheme is then reformulated as a quadratic program (QP). To solve this QP problem online, a simplified linear-variational-inequality based primal-dual neural network (i.e., S-LVI-PDNN) is designed. With simple piecewise-linear dynamics and global exponential convergence to the optimal solution, such an S-LVI-PDNN solver can handle the strictly convex QP problem in an inverse-free manner. Finally, three given tasks, i.e., rhombic path, straight-line path and square path tracking tasks, are fulfilled by three-link, four-link and five-link planar robot arms, respectively. Computer-simulation and physical experiment results validate the physical realizability, efficacy and accuracy of the ARMP scheme and the corresponding S-LVI-PDNN solver.

Research on Path Tracking Control for Vision Based Intelligent Vehicle

This paper proposes an optimal control method to achieve the path tracking mission for the vision based intelligent vehicle. After the access of road trajectory, path tracking task is achieved by the intelligent vehicle automatic steering devices. The angle deviation and lateral deviation relative to the target path can be controlled in the smaller range by state feedback optimal control. A car model contained road information is established for the achievement of intelligent vehicle path tracking and automatic steering. Some values of the variables needed for the control system are obtained by sensors mounted on the car, and achieve the path tracking by the optimal state feedback controller. The algorithm proposed has been validated by simulations. It can make the lateral deviation within the expected range stability. And also the lateral acceleration meets the ride comfort requirements.

Reducing a class of polygonal path tracking to straight line tracking via nonlinear strip-wise affine transformation

In this paper a piecewise linear homeomorphism is presented that maps a strictly monotone polygonal chain to a straight line. This mapping enables one to reduce the path tracking task for mobile robots to straight line tracking. Due to the simplicity of the transformation, closed form solutions for the direct and inverse mapping are presented. Furthermore, the transformation also defines a feedback equivalence relation between the original and the transformed system equations of the mobile robot. It is shown that the form of the system equations is preserved and that the transformation essentially maps a car-like robot in the original domain, to a car-like robot in the transformed domain. This enables one to use straight line trackers developed solely for this system, for the tracking of arbitrary strictly monotone polygonal curves. Finally, it is shown that the use of this mapping can also simplify the application of existing path tracking controllers since they only need to track straight line paths. In general, one can eliminate from the existing path controllers all parameters that are needed for non-straight paths, thus obtaining respective simplified controllers. For example, it is shown that a fuzzy path controller with 135 rules can be reduced to an equivalent fuzzy straight line tracking controller with 45 rules.

Adaptive and Predictive Path Tracking Control for Off-road Mobile Robots

A major problem in the design of control laws dedicated to mobile robots appears when the classical hypothesis of rolling without sliding wheels is violated. It is generally the case for off-road vehicles as adherence conditions are often not satisfactory and sliding can then cease to be negligible. Consequently theoretical performance is impaired and the vehicle is no longer accurately controlled. It is particularly harmful with respect to path tracking tasks, where a loss of accuracy in rough terrain can generate a hazardous situation. Previous work based on the assumption of rolling without sliding has shown very satisfactory results with respect to that task when sliding is not preponderant. It has also made it possible to pinpoint and study the effects of sliding when it appears to be non-negligible. To preserve path tracking accuracy with respect to this phenomenon, a new control law based on an extended kinematic model (updated on-line via an adaptive method) is proposed and discussed. Such control is very efficient when adherence conditions are constant, but overshoots can appear when an abrupt variation is recorded (which is especially the case at the beginning/ end of curves due to low level delays and inertial effects). A model predictive control approach is then added to limit such transient phases in cases where a curved path is followed. The paper is organized as follows: the extended kinematic model is presented as well as the observation of unmeasured parameters required to feed it. A nonlinear control law can then be designed and the results obtained are discussed. Finally, the model predictive control approach is integrated and the overall control scheme is presented. The capabilities of the approach described in this paper are then discussed through full scale experiments.

Follow the Past: a path-tracking algorithm for autonomous vehicles

A number of algorithms for path tracking are described in the robotics literature. Traditional algorithms, like Pure Pursuit and Follow the Carrot, use position information to compute steering commands that make a vehicle follow a pre-defined path approximately. These algorithms are well known to cut corners, since they do not explicitly take into account the actual curvature of the path. In this paper we present a novel algorithm that uses recorded steering commands to overcome this problem. The algorithm is constructed within the behavioural paradigm common in intelligent robotics and is divided into three separate behaviours, each responsible for one aspect of the path-tracking task. The algorithm is implemented both on a simulator for autonomous forest machines and a physical small-scale robot. The results are compared with the Pure Pursuit and the Follow the Carrot algorithms and show a significant improvement in performance.

Solving function distribution and behavior design problem for cooperative object handling by multiple mobile robots

This paper addresses the function distribution and behavior design problem for a multirobot system which incorporates a behavior-based dynamic cooperation strategy for object handling. The proposed multiple robot system is composed of a managing robot and homogeneous behavior-based robots. The cooperation strategy in this system is realized in two steps: designing the distributed robot's cooperative behavioral attributes according to the robot's abilities, and organizing these behavioral attributes so that team cooperation is realized. For indicating an incremental style of local behavior construction, an advanced design of cooperative behavior for coping with unknown disturbance is addressed. Additionally, two extended cooperation strategies designed for a path tracking task are described. These three strategies are based on the same concept on performing manipulation in coordination. Therefore, by considering the function distribution among the managing robot and worker robots, and considering behavior design of each worker robot, the proposed system is able to achieve the object handling task with different performances according to the task requirement, such as with or without path tracking and with or without contact with the environment. Experimental results demonstrate the applicability of the proposed system.

異なるタスクを持つ複数ロボットによる単一物体の協調搬送

A cooperative control method for multiple robots of single object transportation is proposed, which is applicable to unknown environment. In this method, all robots are controlled by the same algorithm, and they can have different objective tasks simultaneously. A task is expressed as the desired position of the object and the associated weight matrix, and each robot can set its own desired position and weight matrix independently of the other robots' tasks. By the proposed method, the robots can cooperatively transport the object to the composite desired position which is the weighted mid point of the desired positions set by all robots, without communicating their tasks with one another. The forces between the robots and the object are controlled as equally as possible during transportation. Furthermore, the internal forces can be suppressed only if some robots in danger of applying large forces broadcast on/off signal to the other robots. Accordingly, this method requires little amount of real-time communication among the robots and does not depend on the number of robots. Owing to these features, the method can deal with the situation where one robot has “path tracking task” and another robot which detects an obstacle has “obstacle avoidance task”; that allows cooperative object transportation with obstacle avoidance in unknown environment. The effectiveness and usefulness of the method are ascertained by computer simulation and experiment.

自動倣い作業ロボットシステムのための断面形状認識

Tracking of a feature point in profile data of the workpiece's joint, using a laser range finder, is indispensable for automating path-tracking tasks, i.e. welding, sealing, deburring, and so on. In this paper, a tracking method is developed that achieves higher work quality and enables looser constraints on the shape of the workpiece. In this method, a profile is recognized by minimizing energy defined by the relationship between measured profile-data points and an articulated object model (AOM), that adjusts to the various changes in profile data by modeling a workpiece's corners, surfaces, and interstices between workpieces. Experiments using a workpiece's profile data measured with a scanning range finder are shown that the proposed method tracks the feature point robustly, even in case of the complicated changes, such as shape transformation from concave to convex, interstice variation, and shape break-down due to obstacles. Moreover, experiments using simulated profile data confirm that the proposed method is robust towards the environmental changes.

センサベーストロボットシステムのための運動情報マネージメント 運動情報に基づく作業点誤差モデリングと倣いロボット診断への応用

Integrated motion information management for use in highly accurate sensor-based robot systems that increases the precision and quality of robotic tasks is described. In this method, the sources of the recognition errors are easily identified by introducing the error-model using the information obtained by the proximity sensor as well as the information about the robot motion acquired by commanded simple testing motions, and these identified error-sources are used to reduce the recogniton errors. Motion reliability is determined based on the robot-motion information, and this reliability is used to reduce the influence of the recognition errors to the whole sensor-based robot system. As a result of this tuning the sensor-based robot system is set up to be close to optimal as possible. Experimental results from a typical visual path-tracking task showed that the tracking error is significantly reduced by using this motion information management system.

Dealing with time-varying parameter problem of robot manipulators performing path tracking tasks

Using the properties of the element by element (or Hadamard) product of matrices, the authors obtain the robot dynamics in parameter-isolated form, from which a new control scheme is developed. The controller proposed yields zero asymptotic tracking errors when applied to robotic systems with time-varying parameters by using a switching type control law. The results obtained are global in the initial state of the robot, and can be applied to rapidly varying systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Motion Relationships in Aircraft Attitude and Guidance Displays: A Flight Experiment

Sixteen nonpilot Naval ROTC students were tested on tasks involving conflicting visual and vestibular cues while flying with each of four basic aircraft attitude presentations (moving horizon, moving airplane, frequency-separated, and kinalog) in a Beechcraft C-45H airplane. Flight-director versions of each display presenting either compensatory or pursuit steering guidance were also compared on a command flight path tracking task involving random heading changes. For all attitude presentations, pursuit tracking was superior to compensatory tracking and the order of merit of the four attitude presentations in flight casts doubt upon the validity of previous simulator experiments. It was concluded that the principle of display frequency separation provides at least equivalent pilot steering performance to that obtained with the conventional moving horizon format, while the anticipatory cues it affords tends to reduce the incidence of control reversals under circumstances of subliminal angular acceleration by providing initial direction-of-motion compatibility.