Summary
This work deals with the leader-follower and the leaderless consensus problems in networks of multiple robot manipulators. The robots are non-identical, kinematically different (heterogeneous), and their physical parameters are uncertain. The main contribution of this work is a novel controller that solves the two consensus problems, in the task space, with the following features: it estimates the kinematic and the dynamic physical parameters; it is robust to interconnecting variable-time delays; it employs the singularity-free unit-quaternions to represent the orientation; and, using energy-like functions, the controller synthesis follows a constructive procedure. Simulations using a network with four heterogeneous manipulators illustrate the performance of the proposed controller. Copyright © 2016 John Wiley & Sons, Ltd.

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Task space consensus in networks of heterogeneous and uncertain robotic systems with variable time‐delays

Neurobehavioral assessment of force feedback simulation in industrial robotic teleoperation


 Increasing the level of automation in material handling tasks in small volume production operations can improve human productivity and overall manufacturing system performance. In this paper, we present a teleoperated mobile manipulator system that can be used for tending machines and transporting parts in manufacturing applications. The remotely located human operator can interact with the semi-autonomous mobile manipulator by giving it high level instructions. We have incorporated several sensors on the system to ensure safe teleoperation where the operator gives only high level motion goals to the mobile manipulator, such as waypoints for mobile base motion, and interactive marker poses for the manipulator motion. The point clouds from multiple depth cameras are used for mapping the environment. The robot plans for autonomous motions between the given way-points ensuring that the resulting motions are collision-free. We have conducted case studies with two different types of parts to be extracted from a 3D printer. The system is tested by multiple users. They were successful in completing tasks in a reasonable amount of time using our interface.

Towards Remote Teleoperation of a Semi-Autonomous Mobile Manipulator System in Machine Tending Tasks

With the integration of mobility and manipulation, mobile manipulator constructed by mobile platform and manipulator has become a potential solution for the fields of industrial manufacturing and services. One of the key issues in utilizing the mobile manipulator is the motion planning, i.e., finding a feasible and efficient trajectory for operation. Compared with the traditional motion planning methods on mobile robot and fixed manipulator, the motion planning of mobile manipulator is more challenging due to the high degree of kinematic redundancy from the coupling of mobile platform and manipulator. And the optimization problem becomes more complicated by the integration of the high degree of kinematic redundancy, obstacle avoidance, constraints and task requirements. To address the issue, the integrated kinematic model is proposed, including mobile platform, manipulator and their coupling property. Subsequently, the coordinated motion planning for mobile manipulator to generate a collision free trajectories from the initial state to target state is developed, where the trajectories of mobile platform and manipulator are planned simultaneously by optimization-based method. The proposed motion planning algorithm is implemented and tested in various environments. Simulation and experiment results demonstrate the good effectiveness of the proposed motion planning algorithm.

Optimization-based motion planning of mobile manipulator with high degree of kinematic redundancy

This paper presents some improvements to the robot kinematic control strategy based on linear programming, as well as its application to a nonholonomic mobile manipulator. In addition to being computationally efficient, this approach enables the inclusion of inequality and equality constraints in the system control inputs and has formal guarantee of stability. We first propose a new positive definite function of the error variation to avoid joint movements when the robot end-effector stabilizes at a point different from the desired one. In addition, the nonholonomic constraint of the mobile base is imposed as an equality constraint, and inequality constraints are defined to avoid both violation of joint limits and collisions between the mobile base and obstacles in the plane. Last, a performance comparison between the linear programming strategy and an approach based on the pseudoinverse of the whole-body Jacobian matrix is presented. Experimental results show that the controller based on linear programming has low computational cost, and the robot is able to control its end-effector without colliding with obstacles in the plane and without violating its joints limits. However, it tends to generate more abrupt control signals than the continuous controller based on the pseudoinverse of the whole-body Jacobian matrix.

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Whole-Body Kinematic Control of Nonholonomic Mobile Manipulators Using Linear Programming

The goal of autonomous mobile manipulation is the execution of complex manipulation tasks in both structured and unstructured environments, possibly in cooperation or close interaction with human beings. This entails challenges in different fields: perception, navigation, task and path planning, control, error recovery, and human-robot interaction. Each field is an area of research on its own, but the special challenge in mobile manipulation is to obtain an integrated system that can combine a large variety of hardware and software components to increase the tasks that the robot can perform, while decreasing the dependency on a priori information and increasing the awareness of the robot to its current situation. Challenges in the field arise from the high-dimensional spaces associated to systems with high number of actuators and sensors, uncertainty in perception and execution of the tasks, generality of the solutions required to manipulate objects in the real world, and engineering and scientific complexity of the systems required for these tasks.

Wes Huang

Papers

Mobile Manipulation: Toward Smart Manufacturing [TC Spotlight]