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1、A rapidly deployable manipulator system combines the flexibility of reconfigurable modular hardware with modular programming tools,allowing the user to rapidly create a manipulator which is custom-tailored for a given task.This article describes two main aspects of such a system，namely,the Reconfigu

2、rable Modular Manipulator System（RMMS）hardware and the corresponding control software.1 IntroductionRobot manipulators can be easily reprogrammed to perform different tasks,yet the range of tasks that can be performed by a manipulator is limited by mechanicalstructure.Forexample，a manipulator well-s

3、uited 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 to choose a manipulator with an appropriate mechanical structure.We propose the concept of a rapidly deployable manipulator

4、 system to address the above mentioned shortcomings of fixed configuration manipulators。As is illustrated in Figure 1，a rapidly deployable manipulator system consists of software and hardware that allow the user to rapidly build and program a manipulator which is customtailored for a given task。The

5、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 of various sizes and performance specifications。One such module is shown in Figure 2。By combining these general purpose modul

6、es，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 well as for industrial applications.However，most of these systems lack the property of reconfigurability，which is key to the

7、 concept of rapidly deployable systems.The RMMS is particularly easy to reconfigure thanks to its integrated quickcoupling connectors described in Section 3.Effective use of the RMMS requires，Task Based Design software。This software takes as input descriptions of the task and of the available manipu

8、lator modules;it generates as output a modular assembly configuration optimally suited to perform the given task.Several different approaches have been used successfully to solve simpli-fied instances of thisA third important building block of a rapidly deployable manipulator system is a framework f

9、or the generation of control software.To reduce the complexity of softwaregeneration for realtime sensor-based control systems,a software paradigm called software assembly has been proposed in the Advanced Manipulators Laboratory at CMU。This paradigm combines the concept of reusable and reconfigurab

10、le software components,as is supported by the Chimera realtime operating system，with a graphical user interface and a visual programming language，inplemented in Onika。Although the software assembly paradigm provides thesoftware infrastructure for rapidly programming manipulator systems，it does not s

11、olve 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 robot to perform the task。The software synthesis problem for sensorbased robots can be simplified dramatically，by providing

12、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 stage without having to consider any of the low-level detailsAs an example of the use of a rapidly deployable system，consider

13、 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 varied kinematic（e。g。，workspace）and dynamic（e.g.,speed,payload）performance is required，and these requirements may not be known

14、 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 the following scenario:as soon as a specific task is identified，the task based design software determinesthe task。This optim

15、al 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 and our library of robotic skills。Finally,the manipulator is deployed to perform its task。Although such a scenario is still fut

16、uristic，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 system。Our approach could form the basis for the next generation of autonomous manipulators，in which the traditional notion of

17、 sensor-based 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 be able to accomplish its task because the task is beyond the systems physical capabilities。A rapidly deployable system，on t

18、he other hand，could adapt its physical capabilities based on task specifications and，with advanced sensing，control，and planning strategies，accomplish the task autonomously.2 Design of selfcontained hardware modulesIn most industrial manipulators,the controller is a separate unit housing the sensor i

19、nterfaces，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,actuators and brakes located in each of the joints of the manipulator.The large number of electrical connections and the nonexten

20、sible 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 the manipulator。These modules then become self-contained units which include sensors,an actuator,a brake,a transmission,a sensor

21、 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。2.1 Mechanical designThe goal of the RMMS project is to have a wide variety of hardware modules available.So far,we have buil

22、t 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 link module have no degrees-of-freedom；the joint modules have degreeof-freedom each.The mechanical design of the joint modules c

23、ompactly fits a DC-motor,a failsafe brake,a tachometer,a harmonic drive and a resolverThe pivot and rotate joint modules use different outside housings to provide the rightangle or in-line configuration respectively,but are identical internally。Figure 4 shows in cross-section the internal structure

24、of a pivot joint。Each joint module includes a DC torque motor and 100：1 harmonicdrive speed reducer,and is rated at a maximum speed of 1。5rad/s and maximum torque of 270Nm。Each module has a mass of approximately 10。7kg。A single，compact，Xtype bearing connects the two joint halves and provides the nee

25、ded 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 designThe custom-designed onboard electronics are also designed according to the principle of modularity.Each RMMS module contains

26、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 80C166 microcontroller，64K of ROM，64K of RAM，an SMC COM20020 universal local area network controller with an RS485 driver，and an

27、 RS-232 driver.The function of the motherboard is to establish communication with the host interface via an RS-485 bus and to perform the lowlevel control of the module,as is explained in more detail in Section 4。The RS232 serial bus driver allows for simple diagnostics and software prototyping.A st

28、acking connector permits the addition of an indefinite number of daughtercards with various functions,such as sensor interfaces，motor controllers，RAM expansion etc。In our current implementation，only modules with actuators include a daughtercard。This card contains a 16 bit resolver to digital convert

29、er，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 oftheshelf motor amplifier（Galil Motion Control model SSA-8/80）to drive the DC-motor.For modules with more than one degree-of-freedom，for instance a wrist module,more

30、than one such daughtercard can be stacked onto由e s创ne motherboard。3 Integrated quickcoupling connectorsTo make a modular manipulator be reconfigurable,it is necessary that the modules can be easily connected with each other.We have developed a quickcoupling mechanism with which a secure mechanical c

31、onnection 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 modules。Turning of the locking collar on the male end produces two distinct motions：first the fingers of the locking ring rota

32、te（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 inward to securely grip the mating flanges。A ball-transfer 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