http://ieeexplore.ieee.org TOC Alert for Publication# 8860 2012 February 10 28 1 C1 C1 71 28 1 C2 C2 39 28 1 1 11 798 28 1 12 21 685 $+$ 1 cables with positive tension to fully constrain it. However, the force-closure analysis of open chains that are driven by cables is still an open question. For the case of an n -DOF cable-driven open chain, the following two important questions arise. 1) How can the force-closure analysis be carried out for a given cable routing configuration, while retaining the geometric insights of the problem? 2) Are n $+$ 1 cables sufficient to fully constrain the entire chain? This paper addresses these issues by proposing a systematic and novel approach based on the reciprocal screw theory. The key idea is to express wrenches acting on the open chain as linear combinations of the reciprocal screws and determine the total required torques at each joint. This is followed by equating the joint torques that are provided by the cable forces with the joint torques, which are required by the external wrenches, and checking for force closure. The proposed methodology can analyze open chains with arbitrary cable routing configuration. The analysis shows that the entire n-DOF open chain requires a minimum of n $+$ 1 cables to fully constrain it.]]> 28 1 22 31 598 $n$ hinged polygons using frictionless point fingers. We first set this problem in the context of classical grasping theory by showing that chain immobilization can only be achieved with equilibrium grasps. Then, we describe two immobilization approaches based on first- and second-order geometric effects. Based on curvature effects, chains of $n ne 3$ hinged polygons with nonparallel edges can be immobilized by $n + 2$ frictionless point fingers. Serial chains of three hinged polygons form an exception to this rule. Based on first-order geometric effects, we describe how to immobilize any chain of $n$ hinged polygons with only one extra contact for the entire chain, using a total of $n + 3$ frictionless point fingers. Moreover, the immobilizing grasps are robust with respect to small contact placement errors. The results are illustrated with examples and described as readily implementable procedures.]]> 28 1 32 43 1054 28 1 44 60 712 28 1 61 76 1203 28 1 77 89 759 28 1 90 100 1067 28 1 101 115 851 $hbox{tt KPIECE}$), which is specifically designed for systems with complex dynamics, where integration backward in time is not possible, and speed of computation is important. A grid-based discretization is used to estimate the coverage of the state space. The coverage estimates help the planner detect the less-explored areas of the state space. An important characteristic of this discretization is that it keeps track of the boundary of the explored region of the state space and focuses exploration on the less covered parts of this boundary. Extensive experiments show that $hbox{tt KPIECE}$ provides significant computational gain over existing state-of-the-art methods and allows us to solve some harder, previously unsolvable problems. For some problems, $hbox{tt KPIECE}$ is shown to be up to two orders of magnitude faster than existing methods and use up to 40 times less memory. A shared memory parallel implementation is presented as well. This implementation provides better speedup than an embarrassingly parallel implementation by taking advantage of the evolving multicore technology.]]> 28 1 116 131 970 28 1 132 144 1227 28 1 145 157 1210 28 1 158 171 1058 ${bm mu }$Bots), with all dimensions under 1 mm, without the need for a specialized surface. We investigate sets of Mag-${bm mu }$ Bots that are geometrically designed to respond uniquely to the same applied magnetic fields. By controlling the magnetic field waveforms, individual and subgroups of Mag-${bm mu }$ Bots are able to locomote in a parallel but dissimilar fashion. The control of geometrically dissimilar Mag- ${bm mu }$Bots and a group of identically fabricated Mag- ${bm mu }$Bots are investigated, and control strategies are developed for 1-D and 2-D motion. This is accomplished by learning the velocity response of each microrobot to various control signals and using the uniqueness of each microrobot response to achieve independent control. The effect of high-level control parameters are investigated in simulation and in experiments, and the simultaneous independent global positioning of two and three microrobots is demonstrated in 2-D space. As this control method is accomplished without the use of a specialized surface, it has potential applications in areas such as microfluidic systems and biomanipulation.]]> 28 1 172 182 829 28 1 183 194 963 28 1 195 212 1666 28 1 213 222 926 28 1 223 233 752 28 1 234 245 1409 28 1 246 255 821 28 1 256 262 630 28 1 262 268 455 28 1 268 275 503 28 1 276 276 320 28 1 C3 C3 31 28 1 C4 C4 34