The Nomad 200 and the Nomad SuperScout
Contents
1. microcontroller then uses PORT K to read into the Bumper s data latch through a multiplexer and determines which of the push but tons is actually depressed This sets a byte in the mi Deore e p B NENG servo amp1lifier SARU A A sal Wks ab S 4 EARN ky DRAR 4 f i AR OA yes i Figure 6 The Nomad 200 with its servo amp ex posed ee INIT S TRANSMIT LIII AL 16 pulses interred ELNE low BINH low INTERNAL k 2 38 ms BLANKING ECHo CO S Figure T Sonar http www acroname com timing diagram crocontroller and the onboard computer which keeps monitoring the state of this byte instructs the micro controller through the serial port to stop all motion by disabling the AMPENABLE on the servo amps 2 2 3 Motor control Mobility on the Nomad 200 is provided by three Pittman DC servo motors The synchronous drive robot has one motor for translation and another for rotation The motion of the individual wheels are linked together The third motor controls the angu lar position of the turret The robot has a zero gyro radius In the original design the GMC 630 motor http www pennmotion com controller card from Galil Motion Control was used as a dedicated card for motor control This card has long since been phased out and no documentation regarding its use is available We contacted Galil Motion Control to obtain a pin out of the GMC 630 motor controlle2. power on the Nomad 200 while retaining its original functional ity We are of course not the only ones to make this observation For example 6 and 7 describe ongo ing efforts to breathe new life into the old Nomad 200s Our goal in upgrading the Nomad 200 was to resurrect it and in the process replace some of its more antiquated components The Intellysis 100 4 microcontroller from Nomadic Technologies was re placed by the Adapt9S12DP256EVP 11 microcon troller from Technological Arts see figure 2 While the onboard computer was replaced by a computer with a 1 Ghz Intel Pentium 3 processor equipped with standard 802 11g networking The Adapt9S512DP256EVP microcon Figure 2 troller 2 2 Microcontroller Integration From a control point of view the Nomad 200 essen tially consists of an onboard computer with a mo torcontroller card along with a microcontroller that controls the onboard sensors Integrating the mi crocontroller was the most challenging part of the project We replaced the Motorola MC68HC11 3 based microcontroller with a microcontroller module based on the current product from the same vendor the 16 bit 9512DP256 8 Although we managed to find some documentation on the Nomad such as 5 and 4 replacing the microcontroller requires much more detailed documentation regarding the opera tion of the sensors and motor control than is pub licly available At the very least the pin out of the int
3. O and BINH pins see figure 8 were connected to PORT A of the microcontroller The four multiplexer select lines are used to fire the 16 transducers in succession and then listen for an echo on each of them Figure 6 shows the timing diagram for firing the sonars The INIT pin is the trigger for pinging the transducer Pulsing this pin high causes the transducer selected by the multiplexer to emit an ultrasonic ping After emit ting the ping the sonar goes into listen mode where it waits for the ECHO pin to go high The sonar determines distance by measuring the time elapsed between setting the INIT pin high and receiving an ECHO i e the instance when the ECHO pin goes high There is an initial default blanking period of 2 8 ms after INIT goes high where the sonar is fires all sonars and writes data back to serial port SCI1 include lt libhclx h gt define PORTH PIM PORTA define PORT SCI1 static char hex 0123456789abcdef static char hexl 8 static volatile dword t elapsed time static volatile dword t current time static volatile dword t start time static volatile byte t echo state static volatile byte t prev_sonar int fire byte t sonar id dword t i j byte_t mask _io ports BASE PIM PORTA PIM R PT amp 0x00 mask 0x01 select sonar _io_ports BASE PIM PORTA PIM R PT sonar_id debounce switch for 0 5 msec start_time clock msecs elapsed time start_time while elapse
4. The Nomad 200 and the Nomad SuperScout Reverse engineered and resurrected Arjun Chopra Mark Obsniuk Michael R Jenkin chopra obsniuk jenkin cs yorku ca Department of Computer Science and Engineering and Centre for Vision Research York University Toronto Ontario Canada February 6 2006 Abstract The Nomad 200 and the Nomad SuperScouts are among the most popular platforms used for research in robotics Built in the early 1990 s they were the base of choice for many mobile robotics researchers Unfortunately lack of support and proper documentation to enhance the computing power on these robots has meant that they have slowly faded away into oblivion We at York University have four robots from Nomadic Technologies Inc and rather than allowing our old robots to just rust away we decided to breathe new life back into them In this paper we present the techniques we used to resurrect our old Nomads Keywords Nomad 200 Nomad SuperScouts Nomad upgrade 1 Introduction Visit any reputable robotics lab anywhere in the world and there is a good chance that you will likely find a robot from Nomadic Technologies a Super Scout a Nomad 200 or a XR4000 in their inventory Sadly however there is an even greater chance that it will be sitting in the farthest corner of the labora tory gathering dust What caused this phenomenon whereby robots like the Nomad 200 which have sig nificant mention in the research litera
5. as used to attach the video digitizer card to the top plate and moth erboard This riser plate needs to be removed and the hard drive and power regulator were mounted directly to the top plate 3 3 2 Software Modifications The first step in configuring the new hardware is to install Linux on the new computer We chose to in stall Debian Linux with a custom 2 6 x Linux kernel We chose to do a network install of the operating system using a netinst CD The CD contains the minimal amount of software to start the installation of the operating system The remaining packages are downloaded from the internet This means an ether net connection for the installation as the drivers for wireless internet connection were not built into the installer at the time we installed Linux We chose a Standard Workstation installation This type of in stall will install the X Window System which allows you to use GUI based applications with a monitor hooked to the computer 4 Conclusions In this paper we described how to refurbish a Nomad SuperScout and a Nomad 200 With some effort we managed to restore these two well known robots with adequate computing power in them to serve as useful platforms for research Consider this statistic We recently acquired a new robot with a forward looking sonar a tactile sensor and an onboard computer with a Pentium M processor for 12000 US The total cost of hardware to upgrade the Nomad 200 was less
6. d time start_time lt 5 elapsed time clock msecs j f fire start_time clock _msecs j elapsed time start_time ping sonar pim set PORTA 6 1 start_time clock msecs pim_set PORTA 4 1 3 i 0 current time clock msecs j elapsed _ time current time start_time blank for 2 8 msec while elapsed time lt 28 2 8 current time clock msecs elapsed time current time start _time should be zero as echo was blanked echo state pim get PORTH 5 leant halnk lar Ea rannira anhast Figure 5 Snippet of code written for controlling the Sensus 200 forced to ignore an echo The BINH pin can be used to force the sonar into the listen mode Setting the BLNK pin high after receiving the first ECHO high is detected allows the sonar to listen to echoes from a more distant object 2 2 2 The Sensus 100 Tactile System The tactile sensor on the Nomad consists of 20 push buttons arranged in two rings of 10 The bumper was not wired to the motor controller in the original de sign To sense a collision the onboard computer con tinuously monitored the bumper s state through the microcontroller and instructed the microcontroller appropriately The microcontroller would then dis able the AMPENABLE on the servo amps to stop all motion We have replicated the same design in our system On sensing a collision the BINT pin of the bumper sensor triggers an interrupt in the mi crocontroller The
7. e at http www senscomp com September 2004 E P Silva J nior P M Engel M Trevisan and M A P Idriart Autonomous learning ar chitecture for environmental mapping Journal of Intelligent and Robotic Systems 39 243 263 2004 TechnologicalArts Adapt9s12dp256 connector pinouts Technical Report AD9S12DP256EVPRla Technological Arts 2002 N C Tsourveloudis K P Valavanis and T Hebert Autonomous vehicle navigation uti lizing electrostatic potential fields and fuzzy logic IEEE Transactions on Robotics and Au tomation 17 4 490 497 August 2001
8. er face for communication with the microcontroller An 802 11 wireless card sits in the PCI slot of the board for communication with a base station Figure 9 shows the new hard drive computer and the micro controller sitting in the original chassis As can be seen the new boards occupy a fraction of the place oc cupied by the original components In fact we could mount the hard drive which was earlier mounted on top of the nomad inside the robot next to the new motherboard board http www galilmc com ABABABAT AAT ALATA Talal MBTEON CONTROL a Bumper and Motion Control interface b Interface to the Sensus 200 J14 MOTION CONTROL Adapt9S12DP256 Microcontroller Sensus 200 Inteface fee i PA1 DATA15 gt in _ oOo oO 6 Z 1i PA5 DATA13 LS 8 T e a 7 is i C o i Co o o o i 21 PAO DATA10 8 3 19 40 ps 44 39 PK2 PK1 m PKO 20 BMPINT AMPEN2 S2 AMPENS3 Si AMPEN1 SO WHM THM J13 BUMPER VIA 3A J15 DATA VIA 3B c Shematic describing how to interface the microcontroller with the individual components of the Nomad 200 Figure 8 Integrating the new microcontroller into the Nomad 200 Ia Figure 10 The refurbished Nomad SuperScouts Gluttony Lust and Envy Figure 9 The Nomad 200 with the new computer and microcontroller installed into the original chas sis 3 Nomad SuperScouts The Nomad Super Scouts are a small robot produced by the Nomad compa
9. erface to the original microcontroller is required Unfortunately none of this information was avail able Instead we had to resort to considerable re verse engineering using a continuity tester data sheets for the ICs and our intuition to identify con nections from the microcontroller to the individual components The Adapt9 S12DP256 microcontroller communicates with the onboard computer through the serial port and was programmed using the GNU Toolchain 2 The detailed results of our efforts are provided below 2 2 1 The Sensus 200 Sonar Ranging System The sonar ranging system figure 3 on the Nomad is a 16 channel system consisting of 16 polaroid trans ducers driven by a Polaroid 6500 ranging board 9 The Polaroid 6500 see figure 4 is a popular board and considerable literature on it can be found on the internet However it is usually used with a sin gle transducer whereas in the Nomad 200 a single polaroid board controls 16 transducers On exam ining the circuitry it was found that the board was multiplexed to the transducers through electronic re lay switches A multimeter intuition and informed guessing were used to interface the sonar ranging x I ROON Ta a we 2 3 woe eo SE Pe Figure 4 A schematic of the Polaroid 6500 module http www acroname com module to the Adapt9 12DP256 microcontroller In our design four selection lines for the multiplexer MO M3 and the BLNK INIT ECH
10. m III 800 MHz CPU but only two were obtained before this model became un available A similar mother board from Nova 7810 is the Nova 7820 which utilizes a 400 MHz VIA CPU So we currently operate two SuperScouts with the Nova 7810 board and one with the Nova 7820 board The Nova 78x0 series of embedded mother boards contain a number of built in features that are very desirable The boards are all low power and have four channel video digitizers built in There is a PCI slot and allows addition of a 802 1la b g wireless card The Nomad Super Scout has the following new hardware Nova 7810 7820 embedded motherboard MSI PC54G2 Wireless 802 11g PCI card based on RaLink 2500 chip set with an external antenna The setup of the system hardware is straight forward The video feed from the video camera is plugged into one of the channels on the motherboard The PCI c New hardware mounted Figure 11 SuperScout top plate wireless card plugs into the PCI slot The installa tion of all the new hardware requires modifications to the top plate which contains all the new hardware The robots use the serial port to communicate with the microcontroller in their base 3 1 Hardware Modifications Although the SuperScouts are somewhat simpler to refurbish than the Nomad 200 not all of the mod ifications are straight forward In the original in stallation the power regulator and hard drive were mounted to a riser plate that w
11. ny These robots were driven by a differential drive which made for easier robot control The robots used industry standard lead acid batteries and could provide power for an hour or so of use depending upon the amount of driving and maneuvering that was required The robots com municated using a Proxim Wireless system This allowed the robots to roam around untethered and still be able to communicate with a base station The Proxim wireless system is not compatible with the 802 11la b g networks The data rate of a Proxim wireless network is very low by todays standards The CPU s that were installed on the Super Scouts were 200 MHz Pentium II with maximum of 4 MB ram Video capture is suppled by an RGB video cam era and this camera uses manual focus and aperture The video was encoded using a PCI based video en coding card The existing mother boards required drivers that are no longer part of the Linux devel oper tree There is no way to update the version of Linux on the Super Scouts due to this change in the Linux device tree In order to run a new version of Linux new mother boards and digitizer hardware is required Luckily there are a number of hardware op tions that are available and have full Linux support The Nomad Super Scout uses a 5 25 form factor Embedded System Mother Board The motherboard that we choose as a replacement is a low power board from Nova We originally planned on using three Nova 7810 MB with Pentiu
12. r card Using this information we were able to diagnose how to interface the pro prietary servo amplifiers from Nomadic Technologies with our new microcontroller We determined that each servo amplifier in the robot requires a 24 V a 5V DC and a GND input from the batteries for power Motor control is accomplished through SIGN PWM and AMP ENABLE inputs The SIGN input determines the direction of rotation of the DC servos while varying the PWM duty cycle varies the rate of rotation We found that a PWM input supplied at a frequency of 23 4 kHz to the amplifiers worked rather well The microcontroller see figure 8 provides PWM SIGN and AMP ENABLE con trol to the amplifiers through the slip ring The DC servo motors also have built in dual channel encoders which are used for odometry The turret and wheels have home position sensors The rotation of the tur ret and wheels is measured relative to the home po sition 2 3 Onboard computer In selecting a new more powerful onboard computer for the Nomad 200 the major constraint was that its power requirements be similar to the original in order to use the existing power supply The Evalue ECM 5612 a socket 370 embedded board was cho sen With a Intel Pentium 3 processor installed the result was an onboard computer with similar power requirements but with a quantum increase in pro cessing power The board also has Firewire and USB ports for additional sensors and a serial port int
13. than 1000 US Acknowledgments Many thanks to Matt Robin son for his HCS12 software libraries and invaluable help while interfacing the components with the mi crocontroller We appreciate Andrew Hogue s help in troubleshooting motor control for the robot The financial support of NSERC is gratefully acknowl edged Shttp www cs yorku ca mobsniuk robot References 1 10 11 ue 12 Laura Barnes Todd Quasny Richard Garcia and L D Pyeatt Multi agent mapping using dynamic allocation utilizing a centralized stor age system In Proceedings of the 12th Annual Mediterranean Conference on Control and Au tomation Kusadasi Aydin Turkey June 2004 Stephane Carrez Using the gnu development tools for 68hc11 and 68hc12 Available at http www gnu m68hc11 org April 2003 Motorola Inc Mc68hc11f1 technical sum mary Technical Summary MC68HC11FTS D Freescale Semiconductor Inc January 1997 Nomadic Technologies Inc Nomad 200 Hard ware Manual February 1997 Nomadic Technologies Inc User s Manual 2 6 edition March 1997 Mattias Lindstrom Nomadic 200 hard ware guide http www nada kth se matti asl nomad200 Francesco Monica Nomad Available at http rimlab ce unipr it July 2005 Motorolalnc Mc9s12dp256b device user guide Technical Report 9S12DP256BDGV2 D Freescale Semiconductor Inc January 2005 SensComplInc 6500 series ranging mod ules specification sheet Availabl
14. therboard and video options provided with the Nomads These factors limit the capability of the Nomad to be used for research even though the basic design and capa bilities are similar to contemporary robots How then can these robots be brought back to full operation and integrated within modern network and operating systems Here we describe our experiences in resurrecting the Nomad 200 and the Nomad Su perScouts It is hoped that these results will encour age others to breath new life into their old robots and let these effective machines live again 2 The Nomad 200 2 1 Overview The Nomad 200 5 is an integrated mobile robot sys tem with a rich suite of sensors including tactile in frared sonar and basic vision systems It consists of a three wheel synchronous drive nonholonomic base on top of which is mounted an independently rotat Figure 1 Sloth The refurbished Nomad 200 ing turret housing sensors and an Intel 80486 based computer Although many Nomad 200s were sold very few are currently active The computer hard ware on the Nomad 200 is almost a decade old Re placement components are difficult to acquire the computer hardware is no longer supported by current Linux drivers and the Nomads use a non standard wireless protocol These factors place severe con straints on using the robot Given the proven success of the basic design of the robot it seems prudent to upgrade and enhance the computing
15. ture see for ex ample 1 10 and 12 have been relegated to the sidelines The original Nomadic Technologies Inc was bought by 3Com Inc in November 2000 Al though 3Com released source code to all drivers li braries and applications which ran on the Nomad se ries of robots 5 these only addressed issues related to software failures For troubleshooting repairing or upgrading the robot hardware data sheets to the various proprietary boards were required Unfortu nately these are not available Inevitably as compo nents failed the robot became immobile The robots at York University were no exception In the VGR lab at York University there are four robots from the Nomad family three SuperScouts Gluttony Lust Greed and one Nomad 200 Sloth Failures in the various computational communication and sensing modules coupled with the lack of external support was quickly rendering these devices obsolete and the situation was quickly approaching the fate that Mar vin the paranoid android of the Hitch Hiker s Guide to the Galaxy lamented do you want me to fall apart where I m standing or shall I just sit in a cor ner and rust These robots contain a wide variety of equipment like the Proxim network cards which are not compatible with today s wireless infrastructure Even the CPUs that came with these robots are gen erations behind what is available today Worse still todays Linux no longer supports the mo
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