Differential-Difference Equations. By Richard Bellman and Kenneth L. Cooke. Pp. xvi, 465. 1963. (Academic Press)

A scheme is developed for classifying the types of motion perceived by a humanlike robot. It is assumed that the robot receives visual images of the scene using a perspective system model. Equations, theorems, concepts, clues, etc., relating the objects, their positions, and their motion to their images on the focal plane are presented. >

http://ieeexplore.ieee.org/iel2/815/3148/00100651.pdf

Robot vision

[서평]「The Unified Modeling Language User Guide」

Summary) The abstract should follow the structure of the article (relevance, degree of exploration of the problem, the goal, the main results, conclusion) and characterize the theoretical and practical significance of the study results. The abstract should not contain wording echoing the title, cumbersome grammatical structures and abbreviations. The text should be written in scientific style. The volume of abstracts (summaries) depends on the content of the article, but should not be less than 250 words. All abbreviations must be disclosed in the summary (in spite of the fact that they will be disclosed in the main text of the article), references to the numbers of publications from reference list should not be made. The sentences of the abstract should constitute an integral text, which can be made by use of the words “consequently”, “for example”, “as a result”. Avoid the use of unnecessary introductory phrases (eg, “the author of the article considers...”, “The article presents...” and so on.)

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Ministry of Education and Science of the Russian Federation

Dynamic analysis of flexible manipulators, a literature review

This paper describes the results of an experimental research on the disturbances acting on the measured force during contact motion of industrial robots. Two phenomena have been found to be mainly responsible for these disturbances, namely the arm structural elasticity due to the torsional flexibility of the joints and the torque ripple of the brushless motors. The structural elasticity is characterized by a resonance frequency function of the arm configuration, while the torque ripple has a principal harmonic of frequency proportional to the motor velocity. Though obtained on a particular experimental setup, these results should be of general interest, since both joint flexibility and torque ripple are common drawbacks of most industrial robots.

Experimental analysis of the disturbances affecting contact force in industrial robots

This paper presents a trajectory optimization approach to the motion generation problem of hybrid locomotion strategies for a wheeled-legged quadrupedal robot with steerable wheels. To this end, traditional Single Rigid Body Dynamics has been employed and extended by adding a unicycle model for each leg, conveniently incorporating the nonholonomic rolling constraints. The proposed approach can generate hybrid locomotion strategies as well as pure driving and legged locomotion with minimum effort for the user. The effectiveness of the proposed approach has been experimentally validated on the humanoid quadruped CENTAURO, employing a hierarchical inverse kinematics engine to track the planned motions.

Optimization-Based Quadrupedal Hybrid Wheeled-Legged Locomotion

The present paper exploits set invariance theory to address the problem of robot implicit force control in presence of stiffness uncertainty in the interaction model. A numerical approach is introduced to compute the invariance function for constraints with arbitrary relative degree. The method is then applied to robot force control, enhancing force regulation performance, in terms of steady state error and convergence speed, despite model mismatch and measurement noise. Its effectiveness is experimentally validated and compared to previous results of set invariance control on a hybrid force/position task performed with a 6 degrees of freedom industrial robot equipped with a force/torque sensor.

Robust set invariance for implicit robot force control in presence of contact model uncertainty

The increasing interest in collaborative robotics applications is mainly due to the flexibility of these robots and to the possibility of saving space on the production shopfloor. On the other hand, physical collaboration is way far from being a commonly adopted practice, and most of the applications only entails a reduced level of interaction. This work addresses the problem of synchronising human and robot activities and proposes a formal control architecture to govern the execution of collaborative application requiring some degree of coordination between the human and the robot. The control architecture is then validated in a realistic collaborative assembly demonstration.

A Formal Control Architecture for Collaborative Robotics Applications

A robot with distributed flexibility in the links and lumped flexibility in the joints is considered in this paper. First the model of the system in free motion is formulated as a set of ordinary differential equations, adopting a finite number of modes of the link deformation. Then algebraic constraint equations on the generalized coordinates of the system are added, to account for the loss of degrees of freedom due to the contact with rigid environment. A reduced order model, expressed in the residual degrees of freedom is then derived, based on a coordinate partitioning procedure. The singularly perturbed model of the system is finally computed, and the expression of the fast subsystem is given. The special cases of a robot with rigid joints or rigid links are also addressed.

Paolo Rocco

Papers

Experimental analysis of the disturbances affecting contact force in industrial robots

Optimization-Based Quadrupedal Hybrid Wheeled-Legged Locomotion

Robust set invariance for implicit robot force control in presence of contact model uncertainty

A Formal Control Architecture for Collaborative Robotics Applications

Singular Perturbation Model of Robots with Elastic Joints and Elastic Links Constrained by Rigid Environment