Integrating computer vision into a robotic system can provide a closed-loop controlled platform that increases the robustness of a robot's motion. This integration is also known as visual servo control or visual servoing. Visual servoing of a robot manipulator in real-time presents complex engineering problems with respect to both control and image processing particularly when we want the robot arm to perform complicated tasks such as portrait drawing. In my research, the implementation of torque feedback control and Image-based Visual Servoing (IBVS) approaches are proposed to improve previous open-loop portrait drawing tasks performed by Betty, a humanoid robot in the Autonomous Agent Lab, University of Manitoba. The implementations and evaluations of hardware, software and kinematic models are discussed in this document. I examined the problem of estimating ideal edges joining points in a pixel reduction image for an existing point-to-point portrait drawing humanoid robot, Betty. To solve this line drawing problem, two automatic sketch generators are presented. First, a modified Theta-graph, called Furthest Neighbour Theta-graph (FNTG). Second, an extension of the Edge Drawing Lines algorithm (EDLines), called Extended Edge Drawing Lines (eEDLines). The results show that the number of edges in the resulting drawing is significantly reduced without degrading the detail of the output image. The other main objective of this research is to propose the extension of the drawing robot project to further develop a robust visual servoing system for Betty to correct any drawing deviation in real-time as a human does. This is achieved by investigating and developing robust feature (lines and shading) extraction approaches for real-time feature tracking of IBVS in combination with adequate torque feedback in the drawing task.

Der Vortrag zeigt dem Anwender CAD basierter Mehrkörpersimulationssoftware, wie dieser durch zwei einfache dynamische Simulationen das reduzierte Massenträgheitsmoment eines ungleichmäßig übersetzenden Getriebes ermitteln kann. Hierbei wird zunächst das Antriebsmoment unter konstanter Antriebsgeschwindigkeit und konstanter Antriebsbeschleunigung ermittelt, aufbereitet und anschließend in die Bewegungsgleichung der starren Maschine eingesetzt. Der Verlauf des reduzierten Massenträgheitsmoments wird für weiterführende Berechnungen (z.B. elektromotorische Antriebsauslegung oder Torque Feedback Simulationen) als Furier-Reihe zur Verfügung gestellt.

Joint torque feedback (JTF) is a new and promising means of kinesthetic feedback to provide information to a person or guide them during a motion task. However, little work has been done to apply the torque feedback to a person. This project evaluates the properties of JTF as haptic feedback, starting from the fabrication of a lightweight elbow haptic exoskeleton. A cheap hobby motor and easily accessible hardware are introduced for manufacturing and open-sourced embedded architecture for data logging. The total cost and the weights are $500 and 509g. Also, as the prerequisite step to assess the JTF in guidance, human perceptual ability to detect JTF was quantified at the elbow during all possible static and dynamic joint statuses. JTF slopes per various joint conditions are derived using the Interweaving Staircase Method. For either directional torque feedback, flexional motion requires 1.89-2.27 times larger speed slope, in mNm/(°/s), than the extensional motion. In addition, we find that JTFs during the same directional muscle's isometric contraction yields a larger slope, in mNm/mNm, than the opposing direction (7.36 times and 1.02 times for extension torque and flexion torque). Finally, the guidance performance of the JTF was evaluated in terms of time delay and position error between the directed input and the wearer's arm. When studying how much the human arm travels with JTF, the absolute magnitude of the input shows more significance than the duration of the input (p-values of <0.0001 and 0.001). In the analysis of tracking the pulse input, the highest torque stiffness, 95 mNm/°, is responsible for the smallest position error, 6.102 ± 5.117°, despite the applied torque acting as compulsory stimuli. / Doctor of Philosophy / Joint torque feedback (JTF) is a new and promising means of haptic feedback to provide information to a person or guide them during a motion task. However, little work has been done to apply the torque feedback to a person, such as determining how well humans can detect external torques or how stiff the torque input should be to augment a human motion without interference with the voluntary movement. This project evaluates the properties of JTF as haptic feedback, starting from the fabrication of a lightweight elbow haptic exoskeleton. The novelty of the hardware is that we mask most of the skin receptors so that the joint receptors are primarily what the body will use to detect external sensations. A cheap hobby motor and easily accessible hardware are introduced for manufacturing and open-sourced software architecture for data logging. The total cost and the weight are $500 and 509g. Also, as the prerequisite step to assess the JTF in guidance, human perceptual ability to detect JTF was quantified at the elbow during all possible static and dynamic joint statuses. A psychophysics tool called Interweaving Staircase Method was implemented to derive torque slopes per various joint conditions. For either directional torque feedback, flexional motion requires 1.89-2.27 times larger speed slope, in mNm/(°/s) than the extensional motion. In addition, the muscles' isometric contraction with the aiding direction required a larger slope, in $mathrm{mNm/mNm}$ than the opposing direction (7.36 times and 1.02 times for extension torque and flexion torque). Finally, the guidance performance of the JTF was evaluated in terms of time delay and position error between the directed input and the wearer's arm. When studying how much the human arm travels with JTF, the absolute magnitude of the input shows more significance than the duration of the input (p-values of <0.0001 and 0.001). In the analysis of tracking the pulse input, the highest torque stiffness, 95 mNm/°, is responsible for the smallest position error, 6.102 ± 5.117°, despite the applied torque acting as compulsory stimuli.

In order to provide the means to set up a control theory lab experiment involving position control of a brushed DC motor with current feedback, a pulse-width modulated motor controller was designed. The output voltage is controlled by an analog reference signal and the magnitude of the output current and voltage are measured and output. These inputs and outputs are connected to a DAQ I/O-unit such that the lab experiment can be implemented digitally. In addition, defining equations for the whole system were derived. Comparison between measurements and model showed it possible to use the current as feedback if low-pass filtered and the angular displacement controlled over a small angular interval.

Der Vortrag zeigt dem Anwender CAD basierter Mehrkörpersimulationssoftware, wie dieser durch zwei einfache dynamische Simulationen das reduzierte Massenträgheitsmoment eines ungleichmäßig übersetzenden Getriebes ermitteln kann. Hierbei wird zunächst das Antriebsmoment unter konstanter Antriebsgeschwindigkeit und konstanter Antriebsbeschleunigung ermittelt, aufbereitet und anschließend in die Bewegungsgleichung der starren Maschine eingesetzt. Der Verlauf des reduzierten Massenträgheitsmoments wird für weiterführende Berechnungen (z.B. elektromotorische Antriebsauslegung oder Torque Feedback Simulationen) als Furier-Reihe zur Verfügung gestellt.