S. L. Chiu, "Task compatibility of manipulator postures," Int. J. Robot. Res., vol. 7, no. 5, pp. 13--21, 1988.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....con guration is optimized for precise force control. Alignment of the principal axes of the hand velocity ellipsoid can be viewed as optimization of manipulator posture to meet task constraints. A general expression for task optimization of manipulator kinematics was introduced by Chiu [4]. We base the error function for the kinematic control law on his derivation of the force transmission ratio. The manipulator force ellipsoid is de ned as follows, where J i is the Jacobian of contact i with respect to the degrees of freedom in the hand: f i i ) f i = 1: As in Chiu s ....

S. Chiu. Task compatibility of manipulator postures. Int'l Journal of Robotics Research, 1988.

....information for both the design of multi purpose robots and for the subsequent planning of efficient movements. Yoshikawa [1] suggested one such measure based on the volume of the manipulability ellipsoid, as derived from a manipulator s kinematic properties, i.e. the Jacobian. Similarly, Chiu [2] viewed a manipulator as a mechanical transformer and used the Jacobian to describe the duality between velocity and force transmission capabilities. Chiu also defined the compatibility index as a basis for computing postures that optimize a robot s performance at a particular task [2] A ....

....Chiu [2] viewed a manipulator as a mechanical transformer and used the Jacobian to describe the duality between velocity and force transmission capabilities. Chiu also defined the compatibility index as a basis for computing postures that optimize a robot s performance at a particular task [2]. A number of extensions to this work dealt with dynamic, as well as kinematic characteristics of the robot. To quantify acceleration capabilities, for example, Yoshikawa later proposed the dynamic manipulability measure [3] which incorporates the manipulator mass matrix in addition to the ....

Stephen L. Chiu, "Task compatibility of manipulator postures," The International Journal of Robotics Research, vol. 7, no. 5, pp. 13--21, 1988.

....and future work. 2 Hyper redundant Manipulator Control Previous work on the control of redundant manipulators has focused on their kinematics, involving the computation and inversion of the Jacobian mapping from joint space to the end effector space [Khatib, 1987; Ghosal and Roth, 1988; Chiu, 1988] These approaches typically include few or no constraints and have been applied to robots with a small number of degrees of freedom (less than 10) Attempts have been made to include more constraints by extending Jacobian methods with projected gradients of the constraints [Baillieul, 1986] or ....

S. L. Chiu. Task compatibility of manipulator postures. Int. J. of Robotics Research, 7(5):13--21, 1988.

....J J T JJ T ( 1 = p n d = n n e n f n e i n q e cos n f n q f cos 109 7.8. 3 The Optimization Criterion The precision grasp may be generated using a variety of task oriented measures such as the manipulability measure [159] task compatability index [25], sum of force minimization [96] measures based on the task ellipsoid [85] among many others. We illustrate the notion of generating the precision grasp by local perturbation using Chiu s task compatability index [25] Chiu [25] views the manipulator as a mechanical transformer with joint ....

....measures such as the manipulability measure [159] task compatability index [25] sum of force minimization [96] measures based on the task ellipsoid [85] among many others. We illustrate the notion of generating the precision grasp by local perturbation using Chiu s task compatability index [25]. Chiu [25] views the manipulator as a mechanical transformer with joint velocity and force as input and Cartesian velocity and force as output. The velocity and force transmission characteristics can be represented geometrically as ellipsoids defined as a function of the manipulator Jacobian. ....

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S.L. Chiu, "Task compatibility of manipulator postures," The Int'l Journal of Robotics Research, vol. 7, no. 5, 1988, pp. 13-21.

....for the development of general purpose software for constructing performance measures for very broad class of joint connected multibody systems. Performance measures are already widely used for design and posture optimization for robot arms. Several local measures have been proposed in the past, [19, 3, 5, 11, 15, 4, 6, 2, 8, 9, 1, 13], which are reviewed in [18] In this paper we will deal with the construction of local performance measures for various tasks, for generic robotic devices. Our work has the following novel features: ffl Our measures can be used for complex manipulators, including constrained multibody systems. ....

S. L. Chiu. Task compatibility of manipulator postures. The Int. J. of Robotics Research, 7(5):13--21, 1988.

....smallest. Most local dexterity measures can be defined in terms of simple combinations of these singular values such as their product (determinant) 14] sum (trace) 2] or ratio (condition number) 1] 5] 6] Task specific dexterity measures also require knowledge of the output singular vectors [3]. The most significant of the singular values is oe m , the minimum singular value, since it is by definition the measure of proximity to a singularity and tends to dominate the behavior of both the manipulability (determinant) and the condition number. The minimum singular value is also a measure ....

S. L. Chiu, "Task compatibility of manipulator postures," International Journal of Robotics Research, vol. 7, no. 5, pp. 13--21, October 1988.

.... criterion under the constraint of the specified end effector velocity by choosing z to be the gradient of some function g( 20] Some of the secondary criteria that have been applied include joint range availability [19] singularity avoidance [26] 39] various measures of dexterity [5] [8], 11] 18] 31] 40] 41] and obstacle avoidance [23] 39] The homogeneous solution can also be used to optimize secondary criteria defined in Cartesian space, either to impose a priority to the manipulation variables [28] or to avoid obstacles [23] by using z = J S (I Gamma J J ) ....

....ordered from largest to smallest. The SVD plays a central role with regard to evaluating the dexterity of manipulator configurations since most local dexterity measures such as manipulability [40] 41] isotropy [2] 31] proximity to singularities [18] fault tolerance [22] compatibility [8], and others [5] 11] are simple functions of the SVD. An efficient implementation of the SVD is also critical for the calculation of (2) 4) and ( since they are also easily described in terms of the SVD. In particular, if (6) is written as J = r X i=1 oe i u i v T i (8) where u i ....

S. L. Chiu, "Task compatibility of manipulator postures," International Journal of Robotics Research, vol. 7, no. 5, pp. 13-21, October 1988.

....of as a means of determining the ease of transmission of joint space velocities to end effector velocities. The intersection of u 1 (extended) with the manipulability ellipsoid for a given end effector position is thus the measure we desire. It is part of the task compatibility measure of [9] and can be written analytically as ff = u T 1 (JJ T ) Gamma1 u 1 ] Gamma1=2 (9) We define c(q) for l vectors u i following the form of the so called task compatibility index: c(q) l X i=1 w i ff 2 i (10) where w i are weighting factors for each direction, indicating the ....

S. L. Chiu. Task compatibility of manipulator postures. International Journal of Robotics Research, 7(5):13 -- 21, 1988.

....going to zero. Typically knowledge of such positions is used to design the usable workspace so as to avoid them. However, this does not completely solve the stiffness problem, because the rigidity of the manipulator in some configurations in the usable workspace might be lower than desirable. In [2], Chiu discusses force and velocity ellipsoids for studying task compatibility of a robot in a given posture and uses this formulation on kinematically redundant SLMs. The ellipsoids as discussed have some implications to manipulator stiffness, though none is mentioned. In [7] Gosselin develops ....

S. Chiu. Task Compatibility of Manipulator Postures. The International Journal of Robotics Research, 7(5):13--21, October 1988.

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S. L. Chiu, "Task compatibility of manipulator postures," Int. J. Robot. Res., vol. 7, no. 5, pp. 13--21, 1988.

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S. L. Chiu, "Task compatibility of manipulator postures," Int. J. Robot. Res., vol. 7, no. 5, pp. 13--21, Oct. 1988.

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S. L. Chiu. Task compatibility of manipulator postures. The International Journal of Robotics Research, 7(5):13--21, 1988. 108

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S.L. Chiu, "Task compatibility of manipulator postures," lnt. J. Robotics Res., vol. 7, no. 5, pp. 13 21, 1988.

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