Travis Dick

SEPO: Selecting by pointing as an intuitive human-robot command interface

Pointing to indicate direction or position is one of the intuitive communication mechanisms used by humans in all life stages. Our aim is to develop a natural human-robot command interface using pointing gestures for human-robot interaction (HRI). We propose an interface based on the Kinect sensor for selecting by pointing (SEPO) in a 3D real-world situation, where the user points to a target object or location and the interface returns the 3D position coordinates of the target. Through our interface we perform three experiments to study precision and accuracy of human pointing in typical household scenarios: pointing to a “wall”, pointing to a “table”, and pointing to a “floor”. Our results prove that the proposed SEPO interface enables users to point and select objects with an average 3D position accuracy of 9:6 cm in household situations.

Real-time prediction learning for the simultaneous actuation of multiple prosthetic joints

Integrating learned predictions into a prosthetic control system promises to enhance multi-joint prosthesis use by amputees. In this article, we present a preliminary study of different cases where it may be beneficial to use a set of temporally extended predictions - learned and maintained in real time - within an engineered or learned prosthesis controller. Our study demonstrates the first successful combination of actor-critic reinforcement learning with real-time prediction learning. We evaluate this new approach to control learning during the myoelectric operation of a robot limb. Our results suggest that the integration of real-time prediction and control learning may speed control policy acquisition, allow unsupervised adaptation in myoelectric controllers, and facilitate synergies in highly actuated limbs. These experiments also show that temporally extended prediction learning enables anticipatory actuation, opening the way for coordinated motion in assistive robotic devices. Our work therefore provides initial evidence that realtime prediction learning is a practical way to support intuitive joint control in increasingly complex prosthetic systems.

Realtime Registration-Based Tracking via Approximate Nearest Neighbour Search.

We introduce a new 2D visual tracking algorithm that utilizes an approximate nearest neighbour search to estimate per-frame state updates. We experimentally demonstrate that the new algorithm capable of estimating larger per-frame motions than the standard registration-based algorithms and that it is more robust in a vision-controlled robotic alignment task.

Online Learning in Markov Decision Processes with Changing Cost Sequences

In this paper we consider online learning in finite Markov decision processes (MDPs) with changing cost sequences under full and bandit-information. We propose to view this problem as an instance of online linear optimization. We propose two methods for this problem: MD2 (mirror descent with approximate projections) and the continuous exponential weights algorithm with Dikin walks. We provide a rigorous complexity analysis of these techniques, while providing near-optimal regret-bounds (in particular, we take into account the computational costs of performing approximate projections in MD2). In the case of full-information feedback, our results complement existing ones. In the case of bandit-information feedback we consider the online stochastic shortest path problem, a special case of the above MDP problems, and manage to improve the existing results by removing the previous restrictive assumption that the state-visitation probabilities are uniformly bounded away from zero under all policies.