摘要:

AbstractThe configuration of the Carnegie‐Mellon University Ambler, a six‐legged autonomous walking vehicle for exploring Mars, enables the recovery of a trailing leg past the leading leg to reduce the energy expenditure in terrain interactions. In this article, gaits developed for this unprecedented configuration are described. A stability criterion has been developed that ensures stability of the vehicle in the event of failure of any one of the supporting legs. Periodic gaits developed for the Ambler utilize the Ambler's unique abilities and continuously satisfy the stability criter

ISSN:0741-2223    

DOI:10.1002/rob.4620090102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractHybrid manipulators are parallel‐serial connection robots that give rise to a multitude of highly articulate robotic manipulators. These manipulators are modular and can be extended by additional modules over large distances. Every module has a hemispherical work space and collective modules give rise to highly dexterous symmetrical work space. In this article, some basic designs and kinematical structures of these robot manipulators are discussed, the associated direct and the inverse kinematics formulations are presented, and solutions to the inverse kinematic problem are obtained explicitly and elaborated upon. These robot manipulators are shown to have a strength‐to‐weight ratio many times larger than the value currently available with industrial or research manipulators. This is due to the fact that these hybrid manipulators are stress compensated and have an ultralight weight, yet are extremely stiff due to the fact that the force distribution in their structure is mostly axial. The means of actuation in these manipulators are entirely prismatic and can be provided by ball‐screws with antibacklash nuts or linear induction motors for maximum pr

ISSN:0741-2223    

DOI:10.1002/rob.4620090103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractAn electrically multiplexed robotic tactile sensor has been realized using a monolithic silicon‐integrated circuit coupled to a piezoelectric polyvinylidene fluoride (PVDF) film. The integrated circuit incorporates 25 sensor electrodes arranged in a symmetrical 5 × 5 matrix. Each electrode occupies a 600 × 600 m̈m square area, and they are separated from each other by 600 m̈m. A 25‐m̈m thick PVDF film was experimentally determined to be compatible with the fabrication process, and also yielded very favorable tactile sensing performance characteristics. The response of the tactile sensor is essentially linear for loads spanning 0.8 to 60 g force (gmf). The response bandwidth is 33 Hz, the hysteresis level is very small, and crosstalk is not a significant problem. A novel precharge bias scheme has been implemented to stabilize the pre‐ and postload sensor response. A rudimentary tactile object image measurement process was evaluated to recognize the shapes of circular, rectangular, toroidal, and hexag

ISSN:0741-2223    

DOI:10.1002/rob.4620090104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractMultiple robots are usually required in a flexible manufacturing system or a complex working environment. In particular, when an object under processing is too big or too heavy, a single robot is insufficient to handle it. Two robots are applicable in such case. This article aims to develop a complete mathematical model and an adaptive controller for two robots carrying a common load. It will be shown that the dynamic model of the two‐robot system turns out to be a singular system, taking into account the object dynamics. The condition for which the system model holds is also discussed. The adaptive controller will be used to overcome uncertainties in the object dynamics and robots. The distributed forces in the robot end effectors are determined by an optimal criterion. It will be shown that the adaptive controller surpasses the conventional computed torque controlle

ISSN:0741-2223    

DOI:10.1002/rob.4620090105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis article studies the geometrical condition for closed‐form solutions of forward kinematics of parallel platforms. It is shown that closed‐form solutions are available if 1 rotational degree of freedom (dof) of the moving platform is decoupled from the other 5 dof. Geometrically, this condition is satisfied when five end‐points at the moving platform (or at the base) are colinear. A general case that these five points do not coincide with each other is studied first and is shown to have 16 possible closed‐form solutions. The variations of parallel platforms that satisfy the above‐mentioned geometrical condition are then discussed. Some of them have the additional feature that the three rotational dof are fully decoupled from the 3 translational dof and their closed‐form solutions are further simplified. One particular case has extremely simple forward kinematics and could be used as an alternative to the Stewa

ISSN:0741-2223    

DOI:10.1002/rob.4620090106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractIn dealing with an industrial manipulator, the end‐effector accuracy is a major concern. The positioning of the end effector is determined by the controller that utilizes the data from a closed‐form kinematic inversion. The closed‐form inversion uses nominal, i.e., manufacturer specified, values of link lengths, twists, and offsets. Due to manufacturing tolerances, set‐up, and usage, these nominal parameters may be inaccurate. If the nominal parameters contain built‐in error values, the closed‐form kinematic inversion will yield incorrect joint values, and the actual end‐effector position will deviate from its desired position. One may use a parameter identification method to identify the position‐independent error parameter values. This article assumes that this has been done and it presents an iterative compensation algorithm (ICA) through which the identified position‐independent parameter error values may be used to correct the joint values obtained through the closed‐form kinematic inversion. The Denavit and Hartenberg (D‐H) parameters (θsαa) are used to model the givenM‐jointed manipulator, and a set of four special Jacobian matrices (Jθ,Js,Jα, andJa) are formulated. The iterative compensation algorithm allows one to determine theMunknown position‐dependent joint error values by using these four special Jacobian matrices. The improvements obtained through the use of the compensation algorithm will be presented for regular trajectories, as well as when the robot nears certain singularity conditions. Since it is important to know a priori a definite number of iterations that must be performed, the level of compensation after a fixed number of iterations is also studied. Through the presentation of numerous examples, it is shown that the proposed compensation algorithm is simple and straightforward to implement, and it increa

ISSN:0741-2223    

DOI:10.1002/rob.4620090107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0741-2223    

DOI:10.1002/rob.4620090101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY