Browsing by Author "Tsai, Lung-Wen"
Now showing 1 - 12 of 12
Results Per Page
Sort Options
Item Backlash Control via Redundant Drivers: An Experimental Verification(1992) Tsai, Lung-Wen; Chang, Sun-Lai; ISRIn this paper, a novel concept for the control of backlash in geared servo-mechanisms is demonstrated with a prototype manipulator. The concept utilizes unidirectional redundant drives to assure positive coupling of gear meshes at all times and, thereby, eliminates backlash completely. To establish a proof of concept, a two-DOF prototype manipulator with three unidirectional drives is designed and tested. Dynamic model based on Lagrange's formulation is established. a PID controller using computed torque control technique is developed. Two experiments, one with redundant drives and the other without redundant drives, are conducted. The experimental results demonstrate that use of unidirectional redundant drives improves the repeatability of a manipulator by an order of magnitude.Item Computer-Aided Sketching of Epicyclic-Type Automatic Transmission Gear Trains(1995) Chatterjee, Goutam; Tsai, Lung-Wen; ISRThe enumeration of epicyclic gear mechanisms in the form of graphs gives rise to the need of a methodology for reverse transformation, that is, for constructing the mechanisms from graphs. This paper addresses the issue by discretizing an epicyclic gear mechanism into Fundamental Geared Entities. Further, these geared entities are shown to be a conglomeration of four primitives; namely, the carrier, sun, ring, and the planet gear. An algorithm is formulated to create the entities from a graph by using these primitives. The entities are then connected to form a mechanism.Item Enumeration of Epicyclic-Type Automatic Transmission Gear Trains(1995) Chatterjee, Goutam; Tsai, Lung-Wen; ISRAn automotive transmission maintains a proper equilibrium between the power and torque produced by the engine and those demanded by the drive wheels. Most automatic transmissions employ some kind of epicyclic gear mechanisms to achieve the above purpose. The first step in the design process of such a mechanism involves finding a configuration that provides a set of desired speed ratios, and meets other dynamic and kinematic requirements. In this work, the kinematic structural characteristics of epicyclic gear mechanisms have been identified, and a methodology is formulated to systematically enumerate all possible configurations of such mechanisms. This is achieved by defining a canonical graph to represent the mechanisms. Graphs of mechanisms with up to 10 links have been generated using this methodology.Item The Generalized Principle of Inertia Match for Geared Robotic Mechanisms(1990) Chen, Dar-Zen; Tsai, Lung-Wen; ISRIn this paper, the principle of inertia match has been extended from one degree-of-freedom system to multi-degree-of-freedom systems. Based on the concept of maximum acceleration capacity, we have developed a methodology for the determination of gear ratios in geared robotic mechanisms. We have shown that at the optimum design, the mass inertia matrix of the input links reflected at the joint-space is equal to that of the major links, and the maximum acceleration capacity is independent of the gear train arrangement. Several two degree-of-freedom geared robotic mechanisms have been used as design examples to illustrated the principle. Using this methodology, mechanisms can be designed to yield optimum dynamic performance.Item Kinematic Analysis of Epicyclic-Type Transmission Mechanisms Using the Concept of Fundamental Geared Entities(1996) Hsieh, Hsin-I; Tsai, Lung-Wen; ISRA new methodology for the speed ratio analysis of epicyclic-type transmission mechanisms is presented. First, the kinematic characteristics associated with various operation modes of fundamental geared entities are investigated. Then, it is shown that the overall speed ratio of an epicyclic gear mechanism can be expressed in terms of its fundamental geared entities. This method leads to an automated derivation of the speed ratio of an epicyclic-type transmission mechanism without the need of a symbolic manipulation software.Item Kinematic and Dynamic Synthesis of Geared Robotic Mechanisms(1990) Chen, Dar-Zen; Tsai, Lung-Wen; ISRThis paper describes a methodology for the design of geared robotic mechanisms. We have shown that certain gear-coupled manipulators can be designed to possess an isotropic condition at a given end-effector position. For these gear-coupled manipulators, the train values can be treated as a product of two-stage gear reductions. The second-stage reduction can be uniquely determined from the kinematic isotropic condition, while the first-stage reduction can be determined from dynamic consideration. This approach, through proper choice of gear ratios, can provide these gear-coupled manipulators with desired kinematic and dynamic characteristics.Item On the Redundant-Drive Backlash-Free Robotic Mechanisms(1990) Chang, Sun-Lai; Tsai, Lung-Wen; ISRIn this paper, we introduce a new and innovative concept for the control of backlash in gear-coupled robotic mechanisms. The concept utilizes redundant unidirectional drives to assure positive coupling of gear meshes at all times. Based on this concept, a methodology for the enumeration of admissible redundant-drive backlash-free robotic mechanisms has been established. Some typical two-and three-DOF mechanisms have been sketched. Furthermore, actuator torques have been derived as functions of either joint torques or end-effector dynamic performance requirements. A redundantly driven manipulator has the fail-safe advantage in that, except of the loss of backlash control, it can continue to function when one of its actuators fails. It does not have the compliance problem associated with tendon-driven manipulators. A two-DOF backlash-free experimental arm is currently under construction to demonstrate the principle.Item Optimization of a Three DOF Translational Platform for Well- Conditioned Workspace(1997) Stamper, Richard E.; Tsai, Lung-Wen; Walsh, Gregory C.; ISRTwo optimization studies on the design of a three degree of freedom translational parallel platform are conducted and the results are compared. The objective function of the first study maximizes total volume of the manipulator workspace without regard to the quality of the workspace. The second study optimizes the total volume of well conditioned workspace by maximizing a global condition index. The global condition index is a function of the condition number of the Jacobian matrix, providing a means of measuring the amplification error between the actuators and the end effector. Both objective functions involve an integration over the workspace of the manipulator. This integral is approximated using the Monte Carlo method.Item A Parallel Manipulator with Only Translational Degrees of Freedom(1997) Tsai, Lung-Wen; Stamper, Richard E.; ISRThis report presents a novel three degree of freedom parallel manipulator that employs only revolute joints and constrains the manipulator output to translational motion. Closed-form solutions are developed for both the inverse and forward kinematics. It is shown that the inverse kinematics problem has up to four real solutions, and the forward kinematics problem has up to 16 real solutions.Item Synthesis and Analysis of Geared Robotic Mechanisms.(1988) Chang, Sun-Lai; Tsai, Lung-Wen; ISRIn this paper we introduce the concept of transmission lines for kinematic analysis and synthesis of geared robotic mechanisms. It is shown that the structural matrix, which relates input displacements to the joint angles of a multi-degree-of-freedom geared robotic mechanism, can be derived using the concept of transmission lines. Applying the characteristics of structural matrix, a new methodology for structural synthesis of articulated mechanisms has been established. All the basic admissible structural matrices of three-degree-of-freedom robotic mechanisms have been enumerated to demonstrate the principle. Several arm and wrist mechanisms created are believed to be new and novel.Item Systematic Enumeration of Parallel Manipulators(1998) Tsai, Lung-Wen; Tsai, Lung-Wen; ISRIn this paper, a systematic methodology for enumeration of the kinematicstructures of parallel manipulators is presented. Parallel manipulators areclassified into planar, spherical, and spatial mechanisms. The classificationis followed by an enumeration of the kinematic structures according to thedegrees of freedom and connectivity listing. In particular, a class ofparallel manipulators with pure translational motion capability is enumerated.Item A Systematic Methodology for the Dynamic Analysis of Articulated Gear-Mechanisms(1990) Chen, Jie; Chen, Dar-Zen; Tsai, Lung-Wen; ISRThis paper describes a systematic methodology for the dynamic analysis of a general class of articulated gear-mechanisms. The approach is based on recently published results related to the kinematic and dynamic analyses of such gear systems. We have shown that the Lagrange's equations of motion can be derived in terms of the minimum number of generalized coordinates in a systematic manner. We have also shown that constraint forces and torques can be evaluated systematically and efficiently, once the equations of motion have been solved. The procedure can be automated in a computer program.