Articulated robot

About: Articulated robot is a research topic. Over the lifetime, 4364 publications have been published within this topic receiving 52442 citations.

Automatic Deployment of Robotic Teams

Abstract: A major goal in robot motion planning and control is to be able to specify a task in a high-level, expressive language and have the robot(s) to automatically convert the specification into a set of low-level primitives, such as feedback controllers and communication protocols, to accomplish the task. The robots can vary from manipulator arms used in manufacturing or surgery, to autonomous vehicles used in search and rescue or in planetary exploration, and to smart wheel chairs for disabled people. They are subject to mechanical constraints (e.g., a carlike robot cannot move sideways,an airplane cannot stop in place) and have limited computation, sensing, and communication capabilities. The environments can be cluttered with possibly moving and shape-changing obstacles and can con tain dynamic (moving, appearing, or disappearing) targets. One of the major challenges in this area is the development of a computationally efficient frame work accommodating both the robot constraints and the complexity of the environment, while, at the same time, allowing for a large spectrum of task specifications.

Performance in adaptive manipulator control

Abstract: The authors explore the performance issues linked to the effective implementation of adaptive controllers for manipulators, which are nonlinear time-varying MIMO systems. Specifically, they detail issues of computational efficiency and recursive implementation, the treatment of closed chains, and minimal parameterizations. The authors also discuss extensions to interactions with mobile environments, whole-arm adaptive manipulation, adaptive impedance control, and adaptive control of spacecraft and space manipulators. The development is illustrated experimentally on a four-degree-of-freedom articulated robot arm, and suggests that the range of application of adaptive tracking controllers may extend well beyond adaptation to grasped loads. >

Hybrid Position/Force Control of Robot Manipulators

Abstract: In proposed method for task-oriented control of robot manipulator, position and force error signals for each task degree of freedom are used to calculate appropriate control parameters in task coordinates. Position and force error signals are transformed and summed to create drive signal for each actuator. New hybrid control technique does not require operator to supply complex transform matrices. Control trajectories are easily visualized in terms of task to be performed.

An Acceleration-based State Observer for Robot Manipulators with Elastic Joints

Abstract: Robots that use cycloidal gears, belts, or long shafts for transmitting motion from the motors to the driven rigid links display visco-elastic phenomena that can be assumed to be concentrated at the joints. For the design of advanced, possibly nonlinear, trajectory tracking control laws that are able to fully counteract the vibrations due to joint elasticity, full state feedback is needed. However, no robot with elastic joints has sensors available for its whole state, i.e., for measuring positions and velocities of both motors and links. Several nonlinear observers have been proposed in the past, assuming different reduced sets of measurements. We introduce here a new observer which uses only motor position sensing, together with accelerometers suitably mounted on the links of the robot arm. Its main advantage is that the error dynamics on the estimated state is independent from the dynamic parameters of the robot links, and can be tuned with standard decentralized linear techniques (locally to each joint). We present an experimental validation of this observer for the three base joints of a KUKA KR15/2 industrial robot and illustrate the control use of the obtained results.

Pipe Network Locomotion with a Snake Robot

Abstract: We present a method of achieving whole-body compliant motions with a snake robot that allows the robot to automatically adapt to the shape of its environment. This feature is important to pipe navigation because it allows the robot to adapt to changes in diameter and junctions, even though the robot lacks mechanical compliance or tactile sensing. Rather than reasoning in the configuration space of robot joint angles, the compliant controller estimates the overall state of the robot in terms of the parameters of a low-dimensional control function, i.e., a gait. The controller then commands new gait parameters relative to that estimated state. Performing closed-loop control in this lower-dimensional parameter space, rather than the robot's full configuration space, exploits the intuitive connection between the gait parameters and higher-level robot behavior. Furthermore, the ability to automatically adjust gait parameters with this controller enables more sophisticated motions that would previously have been too complex to be controlled manually.