机械手相关的外文文献.docx

1、机械手相关的外文文献附件一:A Rapidly Deployable Manipulator SystemAuthor:Christiaan J。J。Paredis,H.Benjamin Brown，Pradeep K.KhoslaAbstract：A rapidly deployable manipulator system combines the flexibility of reconfigurable modular hardware with modular programming tools,allowing the user to rapidly create a manipu

2、lator which is custom-tailored for a given task.This article describes two main aspects of such a system,namely，the Reconfigurable Modular Manipulator System(RMMS）hardware and the corresponding control software。1 IntroductionRobot manipulators can be easily reprogrammed to perform different tasks,ye

3、t the range of tasks that can be performed by a manipulator is limited by mechanicalstructure。Forexample,a manipulator wellsuited for precise movement across the top of a table would probably no be capable of lifting heavy objects in the vertical direction.Therefore，to perform a given task,one needs

4、 to choose a manipulator with an appropriate mechanical structure。We propose the concept of a rapidly deployable manipulator system to address the above mentioned shortcomings of fixed configuration manipulators.As is illustrated in Figure 1,a rapidly deployable manipulator system consists of softwa

5、re and hardware that allow the user to rapidly build and program a manipulator which is customtailored for a given task.The central building block of a rapidly deployable system is a Reconfigurable Modular Manipulator System（RMMS）。The RMMS utilizes a stock of interchangeable link and joint modules o

6、f various sizes and performance specifications.One such module is shown in Figure 2。By combining these general purpose modules，a wide range of special purpose manipulators can be assembled。Recently，there has been considerable interest in the idea of modular manipulators，for research applications as

7、well as for industrial applications。However,most of these systems lack the property of reconfigurability，which is key to the concept of rapidly deployable systems.The RMMS is particularly easy to reconfigure thanks to its integrated quick-coupling connectors described in Section 3。Effective use of t

8、he RMMS requires，Task Based Design software。This software takes as input descriptions of the task and of the available manipulator modules；it generates as output a modular assembly configuration optimally suited to perform the given task。Several different approaches have been used successfully to so

9、lve simplified instances of thisA third important building block of a rapidly deployable manipulator system is a framework for the generation of control software。To reduce the complexity of softwaregeneration for realtime sensor-based control systems,a software paradigm called software assembly has

10、been proposed in the Advanced Manipulators Laboratory at CMU.This paradigm combines the concept of reusable and reconfigurable software components，as is supported by the Chimera real-time operating system，with a graphical user interface and a visual programming language,inplemented in Onika.Although

11、 the software assembly paradigm provides thesoftware infrastructure for rapidly programming manipulator systems，it does not solve the programming problem itself.Explicit programming of sensorbased manipulator systems is cumbersome due to the extensive amount of detail which must be specified for the

12、 robot to perform the task。The software synthesis problem for sensor-based robots can be simplified dramatically,by providing robust robotic skills，that is，encapsulated strategies for accomplishing common tasks in the robots task domain。Such robotic skills can then be used at the task level planning

13、 stage without having to consider any of the lowlevel detailsAs an example of the use of a rapidly deployable system，consider a manipulator in a nuclear environment where it must inspect material and space for radioactive contamination,or assemble and repair equipment。In such an environment，widely v

14、aried kinematic（e.g。,workspace)and dynamic(e。g。,speed，payload)performance is required，and these requirements may not be known a priori。Instead of preparing a large set of different manipulators to accomplish these tasksan expensive solutionone can use a rapidly deployable manipulator system.Consider

15、 the following scenario:as soon as a specific task is identified,the task based design software determinesthe task.This optimal configuration is thenassembled from the RMMS modules by a human or，in manipulator。The resulting manipulator is rapidly programmed by using the software assembly paradigm an

16、d our library of robotic skills.Finally,the manipulator is deployed to perform its task。Although such a scenario is still futuristic,the development of the reconfigurable modular manipulator system,described in this paper,is a major step forward towards our goal of a rapidly deployable manipulator s

17、ystem。Our approach could form the basis for the next generation of autonomous manipulators，in which the traditional notion of sensorbased autonomy is extended to configurationbased autonomy。Indeed，although a deployed system can have all the sensory and planning information it needs，it may still not

18、be able to accomplish its task because the task is beyond the systems physical capabilities.A rapidly deployable system，on the other hand,could adapt its physical capabilities based on task specifications and,with advanced sensing,control，and planning strategies,accomplish the task autonomously。2 De

19、sign of self-contained hardware modulesIn most industrial manipulators,the controller is a separate unit housing the sensor interfaces，power amplifiers,and control processors for all the joints of the manipulator.A large number of wires is necessary to connect this control unit with the sensors,actu

20、ators and brakes located in each of the joints of the manipulator。The large number of electrical connections and the non-extensible nature of such a system layout make it infeasible for modular manipulators.The solution we propose is to distribute the control hardware to each individual module of th

21、e manipulator。These modules then become self-contained units which include sensors,an actuator，a brake，a transmission，a sensor interface,a motor amplifier,and a communication interface,as is illustrated in Figure 3。As a result，only six wires are required for power distribution and data communication

22、。2.1 Mechanical designThe goal of the RMMS project is to have a wide variety of hardware modules available.So far,we have built four kinds of modules：the manipulator base，a link module,three pivot joint modules（one of which is shown in Figure 2），and one rotate joint module.The base module and the li

23、nk module have no degreesof-freedom;the joint modules have degreeof-freedom each.The mechanical design of the joint modules compactly fits a DCmotor,a fail-safe brake,a tachometer,a harmonic drive and a resolverThe pivot and rotate joint modules use different outside housings to provide the rightang

24、le or inline configuration respectively，but are identical internally。Figure 4 shows in cross-section the internal structure of a pivot joint.Each joint module includes a DC torque motor and 100：1 harmonic-drive speed reducer，and is rated at a maximum speed of 1。5rad/s and maximum torque of 270Nm.Eac

25、h module has a mass of approximately 10.7kg.A single,compact,X-type bearing connects the two joint halves and provides the needed overturning rigidity。A hollow motor shaft passes through all the rotary components,and provides a channel for passage of cabling with minimal flexing.2。2 Electronic desig

26、nThe custom-designed on-board electronics are also designed according to the principle of modularity。Each RMMS module contains a motherboard which provides the basic functionality and onto which daughtercards can be stacked to add module specific functionality。The motherboard consists of a Siemens 8

27、0C166 microcontroller,64K of ROM,64K of RAM,an SMC COM20020 universal local area network controller with an RS-485 driver,and an RS232 driver。The function of the motherboard is to establish communication with the host interface via an RS485 bus and to perform the lowlevel control of the module，as is

28、 explained in more detail in Section 4.The RS232 serial bus driver allows for simple diagnostics and software prototyping。A stacking connector permits the addition of an indefinite number of daughtercards with various functions,such as sensor interfaces，motor controllers,RAM expansion etc。In our cur

29、rent implementation,only modules with actuators include a daughtercard.This card contains a 16 bit resolver to digital converter，a 12 bit A/D converter to interface with the tachometer，and a 12 bit D/A converter to control the motor amplifier；we have used an ofthe-shelf motor amplifier(Galil Motion

30、Control model SSA8/80）to drive the DCmotor。For modules with more than one degree-of-freedom,for instance a wrist module,more than one such daughtercard can be stacked onto由e s创ne motherboard.3 Integrated quick-coupling connectorsTo make a modular manipulator be reconfigurable,it is necessary that th

31、e modules can be easily connected with each other.We have developed a quickcoupling mechanism with which a secure mechanical connection between modules can be achieved by simply turning a ring handtight;no tools are required。As shown in Figure 5，keyed flanges provide precise registration of the two

32、modules。Turning of the locking collar on the male end produces two distinct motions:first the fingers of the locking ring rotate（with the collar)about 22。5 degrees and capture the fingers on the flanges;second，the collar rotates relative to the locking ring，while a cam mechanism forces the fingers i

33、nward to securely grip the mating flanges.A balltransfer mechanism between the collar and locking ring automatically produces this sequence of motions。At the same time the mechanical connection is made,pneumatic and electronic connections are also established.Inside the locking ring is a modular connector that has 30 male