Robert Muszyński

Singular inverse kinematic problem for robotic manipulators: a normal form approach

In this article, a new method of solving the singular inverse kinematic problem for nonredundant robotic manipulators is proposed, based on normal forms of the manipulator kinematics. A complete solution to the inverse problem is presented under assumption that the kinematics are equivalent to the quadratic normal form. Comparisons with other existing methods, including the singularity-robust inverse, are made that reveal advantages of the normal form approach. Experimental results concerned with singular tracking in the AdeptOne manipulator are reported.

EMYS—Emotive Head of a Social Robot

This paper presents the design, control, and emotion expressions capabilities of the robotic head EMYS. The concept of motion control system based on FACS theory is proposed. On the basis of this control system six basics emotions are designed for EMYS head. The proposed head shapes are verified in experiments with participation of children aged 8–12. The results of the experiments, perception of the proposed design, and control system are discussed.

Instantaneous kinematics and dexterity of mobile manipulators

We consider the kinematics of a mobile manipulator that consists of a nonholonomic (or holonomic) mobile platform and a holonomic manipulator mounted atop of the platform. At any fixed time instant and with fixed initial posture of the platform these kinematics are viewed as a map from a Hilbert space of controls and manipulator joint positions into a task-space of the mobile manipulator, and called the instantaneous kinematics. A derivative of this map is referred to as the instantaneous analytic Jacobian of the mobile manipulator. We derive an instantaneous dexterity matrix and a dexterity measure of the mobile manipulator. The dexterity matrix is used in order to introduce an instantaneous dexterity ellipsoid of the mobile manipulator. Concepts are illustrated with examples of mobile manipulators equipped with both holonomic and nonholonomic mobile platforms.

Singularities of nonredundant robot kinematics

This article is concerned with an investigation of kinematic singularities of nonredundant robot manipulators, conducted toward describing the kinematics by simple mathematical mod els called normal forms. The adopted approach comes from the singularity theory of maps. The analysis is concentrated on kinematic singularities of codimension 1. The kinematics at singular configurations are characterized by a number called the differential degree. It is proved that, if this degree is finite, then the kinematics can be transformed to normal forms called pre-Morin or Morin forms. If the differential degree becomes infinite, the kinematics can be given either the prehyperbolic or the hyperbolic normal form. Special attention has been paid to the kinematics of the Unimation PUMA manipulator. A sin gularity analysis of the PUMA kinematics has shown that in a neighborhood of the shoulder and elbow singular configura tions, the kinematics assume a simple quadratic (Morin) form, whereas at the wrist singularity, the kinematics are represented by the hyperbolic normal form.

Sensing sociality in dogs: what may make an interactive robot social?

This study investigated whether dogs would engage in social interactions with an unfamiliar robot, utilize the communicative signals it provides and to examine whether the level of sociality shown by the robot affects the dogs’ performance. We hypothesized that dogs would react to the communicative signals of a robot more successfully if the robot showed interactive social behaviour in general (towards both humans and dogs) than if it behaved in a machinelike, asocial way. The experiment consisted of an interactive phase followed by a pointing session, both with a human and a robotic experimenter. In the interaction phase, dogs witnessed a 6-min interaction episode between the owner and a human experimenter and another 6-min interaction episode between the owner and the robot. Each interaction episode was followed by the pointing phase in which the human/robot experimenter indicated the location of hidden food by using pointing gestures (two-way choice test). The results showed that in the interaction phase, the dogs’ behaviour towards the robot was affected by the differential exposure. Dogs spent more time staying near the robot experimenter as compared to the human experimenter, with this difference being even more pronounced when the robot behaved socially. Similarly, dogs spent more time gazing at the head of the robot experimenter when the situation was social. Dogs achieved a significantly lower level of performance (finding the hidden food) with the pointing robot than with the pointing human; however, separate analysis of the robot sessions suggested that gestures of the socially behaving robot were easier for the dogs to comprehend than gestures of the asocially behaving robot. Thus, the level of sociality shown by the robot was not enough to elicit the same set of social behaviours from the dogs as was possible with humans, although sociality had a positive effect on dog–robot interactions.

Normal forms of non-redundant singular robot kinematics: Three DOF worked examples

A collection of mathematical models (normal forms) of 3 degree of freedom (DOF) corank 1 singular manipulator kinematics is derived using a general theory presented in Tchon and Muszynski. 1 All 3-DOF kinematic structures, from PPP up to RRR, are investigated. Singular configurations are distinguished by their corank. For each kinematics geometric conditions making the kinematics spatial and defining the corank of the appropriate Jacobian matrix are established. Several instructive examples of kinematic singularities are examined in detail and given a readable geometric interpretation.

Humans attribute emotions to a robot that shows simple behavioural patterns borrowed from dog behaviour

In social robotics it has been a crucial issue to determine the minimal set of relevant behaviour actions that humans interpret as social competencies. As a potential alternative of mimicking human abilities, it has been proposed to use a non-human animal, the dog as a natural model for developing simple, non-linguistic emotional expressions for non-humanoid social robots. In the present study human participants were presented with short video sequences in which a PeopleBot robot and a dog displayed behaviours that corresponded to five emotional states (joy, fear, anger, sadness, and neutral) in a neutral environment. The actions of the robot were developed on the basis of dog expressive behaviours that had been described in previous studies of dog-human interactions. In their answers to open-ended questions, participants spontaneously attributed emotional states to both the robot and the dog. They could also successfully match all dog videos and all robot videos with the correct emotional state. We conclude that our bottom up approach (starting from a simpler animal signalling system, rather than decomposing complex human signalling systems) can be used as a promising model for developing believable and easily recognisable emotional displays for non-humanoid social robots. Humans spontaneously attribute emotions to an ethologically inspired robot.Dog emotional videos prime the attribution of emotions to robot videos.Participants were able to match both dog and robot videos to the corresponding emotions.Experience with dogs does not help identify dog and robot emotions.

A solution to the singular inverse kinematic problem for a manipulation robot mounted on a track

Abstract Using the normal form approach we have solved the singular inverse kinematic problem for the ASEA IRb-6 manipulator mounted on a track. It is established that in a neighbourhood of singular configurations the kinematics of this manipulator assume the hyperbolic normal form. Equivalence transformations of the kinematics into the normal form are found. A normal-form based inversion algorithm of singular kinematics is presented. This algorithm is illustrated with computer simulations that reveal excellent quality of the normal form solution. Although the approach has been illustrated on an exemplary robot it applies to a general manipulation robot mounted on a track.

A normal form solution to the singular inverse kinematic problem for robotic manipulators: the quadratic case

We present a normal form approach to solving the singular inverse kinematic problem for non-redundant robot kinematics. A standing assumption is made that singular configurations of the kinematics have corank 1 and that the kinematics are equivalent to the quadratic normal form. The approach has been illustrated with a simulation case study of 2R kinematics. A comparison with the singularity-robust inverse technique and the null-space based approach has demonstrated advantages of the normal form approach.

Singularities and Mobility of Nonholonomic Systems: The Ball Rolling on a Plane

Abstract Using a representation of the kinematics by means of a driftless control system we define posture and configuration singularities of a nonholonomic robotic system. A mobility ellipsoid is adopted as an indicator of mobility of the system. The concepts of singularities and mobility are illustrated with an example of the ball rolling on a plane.