2。5 Modular and reconfigurable control software

The control software for the RMMS has been developed using the Chimera real-time operating system, which supports reconfigurable and reusable software components 。 The software components used to control the RMMS are listed in Table 。 The trjjline, dls, and grav_comp components require the knowledge of certain configuration dependent parameters of the RMMS, such as the number of degrees-of-freedom, the Denavit-Hartenberg parameters etc。 During the initialization phase, the RMMS interface establishes contact with each of the hardware modules to determine automatically which modules are being used and in which order and orientation they have been assembled。 For each module, a data file with a parametric model is read。 By combining this information for all the modules, kinematic and dynamic models of the entire manipulator are built。论文网

After the initialization, the rmms software component operates in a distributed control mode in which the microcontrollers of each of the RMMS modules perform PID control locally at 1900Hz。 The communication between the modules and the host interface is at 400Hz, which can differ from the cycle frequency of the rmms software component。 Since we use a triple buffer mechanism  for the communication through the dual-port RAM on the ARMbus host interface, no synchronization or handshaking is necessary。

Because closed form inverse kinematics do not exist for all possible RMMS configurations, we use a damped least-squares kinematic controller to do the inverse kinematics computation numerically。

2。6 Seamless integration of simulation

To assist the user in evaluating whether an RMMS con- figuration can successfully complete a given task, we have built a simulator。 The simulator is based on the TeleGrip robot simulation software from Deneb Inc。, and runs on an SGI Crimson which is connected with the real-time processing unit through a Bit3 VME-to-VME adaptor。 A graphical user interface allows the user to assemble simulated RMMS configurations very much like assembling the real hardware。 Completed configurations can be tested and programmed using the TeleGrip functions for robot devices。 The configurations can also be interfaced with the Chimera real-time softwarerunning on the same RTPUs used to control the actual hardware。 As a result, it is possible to evaluate not only the movements of the manipulator but also the realtime CPU usage and load balancing。 

2。7 Summary

We have developed a Reconfigurable Modular Manipulator System which currently consists of six hardware modules, with a total of four degrees-of-freedom。 These modules can be assembled in a large number of different configurations to tailor the kinematic and dynamic properties of the manipulator to the task at hand。 The control software for the RMMS automatically adapts to the assembly configuration by building kinematic and dynamic models of the manipulator; this is totally transparent to the user。 To assist the user in evaluating whether a manipulator configuration is well suited for a given task, we have also built a simulator。

Acknowledgment

This research was funded in part by DOE under grant DE-F902-89ER14042, by Sandia National Laboratories under contract AL-3020, by the Department of Electrical and Computer Engineering, and by The Robotics Institute, Carnegie Mellon University。

The authors would also like to thank Randy Casciola, Mark DeLouis, Eric Hoffman, and Jim Moody for their valuable contributions to the design of the RMMS system。

摘 要：一个快速部署的机械手系统的灵活性，可重构模块化的编程工具，可重构模块化的硬件，允许用户快速创建一个机械手，这是自定义的一个给定的任务。这篇文章描述了这样一个系统中，两个主要方面，即，可重构模块化机器人系统（RMMS）的硬件和相应的控制软件。