Robust Cooperative Manipulation without Force/Torque Measurements: Control Design and Experiments

This paper presents two novel control methodologies for the cooperative manipulation of an object by N robotic agents. Firstly, we design an adaptive control protocol which employs quaternion feedback for the object orientation to avoid potential representation singularities. Secondly, we propose a control protocol that guarantees predefined transient and steady-state performance for the object trajectory. Both methodologies are decentralized, since the agents calculate their own signals without communicating with each other, as well as robust to external disturbances and model uncertainties. Moreover, we consider that the grasping points are rigid, and avoid the need for force/torque measurements. Load distribution is also included via a grasp matrix pseudo-inverse to account for potential differences in the agents' power capabilities. Finally, simulation and experimental results with two robotic arms verify the theoretical findings

Cooperative Control of Dual Series Robots

Development in manufacturing, automation, space and underwater exploration has shown vast number of robots being used where most of the existing robots are of coordinated control of a single arm only. Increasing demand for robots application, especially in manufacturing has opened a new challenge; dual arm robot cooperation. This challenge is to develop robots which can carry out greater task which could either be heavy in load or complex in working. The main objectives for this project are to study on the available techniques of cooperative control, to design a program based on the chosen technique, to integrate the program in the system of two existing robot arms handling one common load and to ensure precise tracking of a desired formation and simplicity in its design. The methods being used in this project are performing literature\ud review, selection of cooperative control technique where three cooperative control techniques namely Master/Slave control, Centralized and Decentralized control are compared and implemented to the existing robots, as well as conducting experiment on the real system. Results from the experiment are analyzed and improvised to prove that cooperative control technique could be used for this study. Results from this study are in form of programming of the control system, ladder diagram showing inputs and outputs of the system utilized and calculation of error of relative coordinate of the two robots after experiment execution. In conclusion, master/slave technique has been selected to be most suitable for this study based on its accuracy and simplicity of its design. The objectives for this project have been achieved where no error above lmm recorded which indicates accuracy and number of lines of programming are 21 lines for Master and 16 lines for Slave robot thus, proving its simplicity. However, improvement on the method used could be further studied to minimize number of lines, using other method or extension of this project where rotational motion could be studied

High speed, precision motion strategies for lightweight structures

Research on space telerobotics is summarized. Adaptive control experiments on the Robotic Arm, Large and Flexible (RALF) were preformed and are documented, along with a joint controller design for the Small Articulated Manipulator (SAM), which is mounted on the RALF. A control algorithm is described as a robust decentralized adaptive control based on a bounded uncertainty approach. Dynamic interactions between SAM and RALF are examined. Unstability of the manipulator is studied from the perspective that the inertial forces generated could actually be used to more rapidly damp out the flexible manipulator's vibration. Currently being studied is the modeling of the constrained dynamics of flexible arms

Cooperative Control of the Dual Gantry-Tau Robot

Utilization of multiple parallel robots operating in the same work place and cooperating on the same job have opened up new challenges in coordination control strategies. Multiple robot control is a natural progression for Parallel Kinematic Machines (PKM) as it offers many of the desirable qualities especially in cooperative arrangements where multiple robots can be associated with an easily reconfigurable parallel machine. These special characteristics allow much faster and precise manipulations especially in manufacturing industries. With the possibility of cooperative control architecture, PKMs will be able to perform many of the tasks currently requiring dual serial robots such as complex assemblies, heavy load sharing and large machining jobs

Decentralized Adaptive Control for Collaborative Manipulation of Rigid Bodies

In this work, we consider a group of robots working together to manipulate a rigid object to track a desired trajectory in $SE(3)$. The robots do not know the mass or friction properties of the object, or where they are attached to the object. They can, however, access a common state measurement, either from one robot broadcasting its measurements to the team, or by all robots communicating and averaging their state measurements to estimate the state of their centroid. To solve this problem, we propose a decentralized adaptive control scheme wherein each agent maintains and adapts its own estimate of the object parameters in order to track a reference trajectory. We present an analysis of the controller's behavior, and show that all closed-loop signals remain bounded, and that the system trajectory will almost always (except for initial conditions on a set of measure zero) converge to the desired trajectory. We study the proposed controller's performance using numerical simulations of a manipulation task in 3D, as well as hardware experiments which demonstrate our algorithm on a planar manipulation task. These studies, taken together, demonstrate the effectiveness of the proposed controller even in the presence of numerous unmodeled effects, such as discretization errors and complex frictional interactions

Cooperative Control of Dual Series Robots

Development in manufacturing, automation, space and underwater exploration has shown vast number of robots being used where most of the existing robots are of coordinated control of a single arm only. Increasing demand for robots application, especially in manufacturing has opened a new challenge; dual arm robot cooperation. This challenge is to develop robots which can carry out greater task which could either be heavy in load or complex in working. The main objectives for this project are to study on the available techniques of cooperative control, to design a program based on the chosen technique, to integrate the program in the system of two existing robot arms handling one common load and to ensure precise tracking of a desired formation and simplicity in its design. The methods being used in this project are performing literature review, selection of cooperative control technique where three cooperative control techniques namely Master/Slave control, Centralized and Decentralized control are compared and implemented to the existing robots, as well as conducting experiment on the real system. Results from the experiment are analyzed and improvised to prove that cooperative control technique could be used for this study. Results from this study are in form of programming of the control system, ladder diagram showing inputs and outputs of the system utilized and calculation of error of relative coordinate of the two robots after experiment execution. In conclusion, master/slave technique has been selected to be most suitable for this study based on its accuracy and simplicity of its design. The objectives for this project have been achieved where no error above lmm recorded which indicates accuracy and number of lines of programming are 21 lines for Master and 16 lines for Slave robot thus, proving its simplicity. However, improvement on the method used could be further studied to minimize number of lines, using other method or extension of this project where rotational motion could be studied

Passivity-Based adaptive bilateral teleoperation control for uncertain manipulators without jerk measurements

In this work, we consider the bilateral teleoperation problem of cooperative robotic systems in a Single-Master Multi-Slave (SM/MS) configuration, which is able to perform load transportation tasks in the presence of parametric uncertainty in the robot kinematic and dynamic models. The teleoperation architecture is based on the two-layer approach placed in a hierarchical structure, whose top and bottom layers are responsible for ensuring the transparency and stability properties respectively. The load transportation problem is tackled by using the formation control approach wherein the desired translational velocity and interaction force are provided to the master robot by the user, while the object is manipulated with a bounded constant force by the slave robots. Firstly, we develop an adaptive kinematic-based control scheme based on a composite adaptation law to solve the cooperative control problem for robots with uncertain kinematics. Secondly, the dynamic adaptive control for cooperative robots is implemented by means of a cascade control strategy, which does not require the measurement of the time derivative of force (which requires jerk measurements). The combination of the Lyapunov stability theory and the passivity formalism are used to establish the stability and convergence property of the closed-loop control system. Simulations and experimental results illustrate the performance and feasibility of the proposed control scheme.No presente trabalho, considera-se o problema de teleoperação bilateral de um sistema robótico cooperativo do tipo single-master e multiple-slaves (SM/MS) capaz de realizar tarefas de transporte de carga na presença de incertezas paramétricas no modelo cinemático e dinâmico dos robôs. A arquitetura de teleoperação está baseada na abordagem de duas camadas em estrutura hierárquica, onde as camadas superior e inferior são responsáveis por assegurar as propriedades de transparência e estabilidade respectivamente. O problema de transporte de carga é formulado usando a abordagem de controle de formação onde a velocidade de translação desejada e a força de interação são fornecidas ao robô mestre pelo operador, enquanto o objeto é manipulado pelos robôs escravos com uma força constante limitada. Primeiramente, desenvolve-se um esquema de controle adaptativo cinemático baseado em uma lei de adaptação composta para solucionar o problema de controle cooperativo de robôs com cinemática incerta. Em seguida, o controle adaptativo dinâmico de robôs cooperativos é implementado por meio de uma estratégia de controle em cascata, que não requer a medição da derivada da força (o qual requer a derivada da aceleração ou jerk). A teoria de estabilidade de Lyapunov e o formalismo de passividade são usados para estabelecer as propriedades de estabilidade e a convergência do sistema de controle em malha-fechada. Resultados de simulações numéricas ilustram o desempenho e viabilidade da estratégia de controle proposta

Challenges and Solutions for Autonomous Robotic Mobile Manipulation for Outdoor Sample Collection

In refinery, petrochemical, and chemical plants, process technicians collect uncontaminated samples to be analyzed in the quality control laboratory all time and all weather. This traditionally manual operation not only exposes the process technicians to hazardous chemicals, but also imposes an economical burden on the management. The recent development in mobile manipulation provides an opportunity to fully automate the operation of sample collection. This paper reviewed the various challenges in sample collection in terms of navigation of the mobile platform and manipulation of the robotic arm from four aspects, namely mobile robot positioning/attitude using global navigation satellite system (GNSS), vision-based navigation and visual servoing, robotic manipulation, mobile robot path planning and control. This paper further proposed solutions to these challenges and pointed the main direction of development in mobile manipulation