Advanced Robotics

Wang, Wei; Xu, Xin; Li, Yan; Song, Jinze; He, Hangen

doi: 10.1163/016918610X496928pmid: N/A

Although Rapidly-exploring Random Trees (RRTs) have been successfully applied in path planning of robots with many degrees of freedom under non-holonomic and differential constraints, rapidly identifying and passing through narrow passages in a robot's configuration space remains a challenge for RRTs-based planners. This paper presents a novel two-stage approach to address the problem of multi-d.o.f. robot path planning in high-dimensional configuration space with narrow corridors. The first stage introduces an efficient sampling algorithm called Bridge Test to find a global roadmap that identifies the critical region. The second stage presents two varieties of RRTs, called Triple-RRTs, to search for a local connection under the guidance of the global landmark. The two-stage strategy keeps a fine balance between global heuristics and local connection, resulting in high performance over the previous RRTs-based path planning methods. We have implemented the Triple-RRTs planners for both rigid and articulated robots in two- and three-dimensional environments. Experimental results demonstrate the effectiveness of the proposed method.

Cherouvim, Nicholas; Papadopoulos, Evangelos

doi: 10.1163/016918610X496937pmid: N/A

In this work we develop a novel method, or mechanism, of energy transfer in a quadruped running robot. The robot possesses only one actuator per leg, for lower weight and greater power autonomy. The developed mechanism ensures correct dispersion of energy to the actuated and the unactuated degrees of freedom of the robot for stable running. In the mechanism design, we address the added problem of running on inclined ground. In conjunction with a pitch control method, the energy transfer mechanism forms a complete control algorithm. Due to the novel dynamics-based design of the mechanism, it allows the arbitrary setting of the motion forward speed and apex height. Further, it may be applied for different robot physical parameters and ground inclines, without extensive controller tuning. This has not been previously possible using only one actuator per leg. Simulations of a detailed three-dimensional model of the robot demonstrate the mechanism on two different robots. The simulations take into account many real-world characteristics, including realistic leg models, energy loss due to feet collisions, foot–ground friction and energy losses in the joints. Results demonstrate that inclines of up to 20° are properly negotiated.

Chung, Shu-Yun; Huang, Han-Pang

doi: 10.1163/016918610X496946pmid: N/A

In recent years, SLAMMOT (simultaneous localization, mapping and moving object tracking) has attracted widespread attention in the mobile robot field. This paper proposes a new approach, SLAMMOT-SP, which combines SLAMMOT and scene prediction (SP). It extends the SLAMMOT problem to simultaneous map prediction and moving object trajectory prediction. The robot not only passively collects the data and executes SLAMMOT, but actively predicts the scene. The recursive Bayesian formulation of SLAMMOT-SP is derived for real-time operations. A generalized framework for tracking and predicting the moving objects is also proposed. Simulations and experiments show that the proposed SLAMMOT-SP is effective and can be performed in real-time.

Hu, Bo; Lu, Yi; Yu, Jianping

doi: 10.1163/016918610X496955pmid: N/A

This paper presents a methodology for the unified analysis of the dynamics of some parallel manipulators (PMs) with n UPS-type active legs and a passive constraining leg. First, some formulae are derived for solving linear/angular velocity of active and constraining legs at their mass center, linear/angular accelerations of active and constraining legs at their mass center, and Jacobian matrices of active and constraining legs. Second, based on the principle of virtual work and Jacobian matrices of active and constraining legs, the inertia wrench and gravity of active/constraining legs and the friction of the joints in a PM are mapped into a part of the dynamic workload. Third, the general formulae are derived for solving the dynamic workload and the dynamic active forces/constrained wrench. Finally, the procedure is illustrated by means of a PM with 4 UPS active legs and one passive constraining leg.

Stulp, Freek; Utz, Hans; Isik, Michael; Mayer, Gerd

doi: 10.1163/016918610X496964pmid: N/A

A striking aspect of human coordination is that we achieve it with little or no communication. We achieve this implicit coordination by taking the perspective of others and inferring their intentions. In contrast, robots usually coordinate explicitly through the extensive communication of utilities or intentions. In this paper we present a method that combines both approaches: implicit coordination with shared belief. In this approach, robots first communicate their beliefs about the world state to each other, using a CORBA-based communication module. They then use learned utility prediction models to predict the utility of each robot locally. Based on these utilities, an action is chosen. Within a heterogeneous soccer team, with robots from both the Munich and Ulm research groups, we apply implicit coordination with shared belief to a typical task from robotic soccer: regaining ball possession. An empirical evaluation demonstrates that the redundancy of implicit coordination with shared belief leads to robustness against communication failure and state estimation inaccuracy.

doi: 10.1163/016918610X546850pmid: N/A

Shiu, Ming-Chiuan; Fu, Li-Chen; Lee, Hou-Tsan; Lian, Feng-Li

doi: 10.1163/016918610X497116pmid: N/A

This paper discusses the modular design of distributed reconfigurable robots. The design concept, mechanical structure, electrical processing unit, actuator dissection and reconfiguration examples of the proposed robotic modules are presented in detail. The reconfigurable robotic motion is realized via a collection of the proposed modules with the capability of connecting and disconnecting with adjacent modules. The key actuation of the robotic reconfiguration is driven only by the E-type electromagnets and different shapes of the modules are implemented for versatile applications. Finally, the feasibility of the proposed robotic modules has been extensively tested.