Instrumented Prodder: Preliminary Results of the Technology Demonstrator Evaluation A.J. Schoolderman 1, S.G.M. van Dijk 1, D. Deurloo 1, K.

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1 Instrumente Proer: Preliminary Results of the Technology Demonstrator Evaluation A.J. Schoolerman 1, S.G.M. van Dijk 1, D. Deurloo 1, K. Russell 1 TNO-FEL P.O. Box JG The Hague The Netherlans schoolerman@fel.tno.nl CCMAT Box 4, Station Main Meicine Hat, Alberta Canaa T1A 8K Kevin.Russell@rc-rc.gc.ca Abstract A proer for mine etection has been enhance with sensors an electronics in orer to provie the operator with information on the force exerte uring the proing operation an on the type of material that is in contact with the tip of the proer. The performance of a technology emonstrator version of this Instrumente Proer is teste uner laboratory conitions, as a start of a prouct evelopment path. For these tests seven ifferent types of objects (inert PMN mines an mine-like objects from stone, PVC, woo an metal) were burie in test lanes with six soil types with ifferent harness an moisture content. The Instrumente Proer was inserte into the soil in such a way that it was possible to ajust the exerte force. From the test results it is conclue that material ientification of burie objects by an instrumente proer is feasible. The low reliability of the material ientification feature of the technology emonstrator as foun in the tests is likely ue to measurement of the contact force between the proer s tip an the burie object. 1. Introuction The proer is one of the most important tools for a eminer involve in humanitarian emining operations. In [1] the history of the conventional proer an improvements on this evice are iscusse. Develope in Canaa, an 'Instrumente Proer' is an attempt to improve on the basic proing tool. This evice is a proer which gives an inication of the type of material (metal, plastic/woo or stone) uner contact with the probe tip. This inication ais the operator with the classification an ientification of the burie object. The first version of the Instrumente Proer, calle 'SmartProbe', was manufacture in a small number by the Canaian company, DEW Engineering an Development Lt., uner a licence from the Canaian Department of National Defence. After extensive fiel testing, it was conclue that the SmartProbe 'i not function as avertise' [, ] an DEW iscontinue the prouct line. The avantage of a force feeback inicator uring manual proing has been stresse by Gasser [4, 5]. Deminers appear not to be aware that the force that they exert on the proer is, in many cases, higher (sometimes even orers of magnitue higher) than the force require to etonate many types of anti-personnel mines. This is of concern especially in countries where the soil is har as proing on anti-personnel mines is a major cause of emining accients. A force feeback signal which warns the operator of excess force being applie, may lea to safer proing. Fune by the Canaian Centre for Mine Action Technology (CCMAT), HF Research Inc. (a Canaian company) initiate a reesign of the Instrumente Proer an prouce a 'technology emonstrator' which is equippe with a force feeback system in aition to the case material ientification feature. The current technology emonstrator version has been subject to a blin test execute in September 1 in Canaa []. In this test more than 1 burie objects (efuse mines as well as mine-like objects such as woo, plastic, an stones) were interrogate by five operators. Though the etection performance of this technology emonstrator version is clearly better than that of the SmartProbe, further evelopment may be necessary to bring the evice up to a level that is acceptable to the humanitarian emining community. It is expecte that in certain emining operations the Instrumente Proer will be very suitable to Non- Governmental Organizations (NGO's) ue to its simple operation an small maintenance buren. If the material inication an force feeback function well an are reliable, the training of local eminers for the operation of the Instrumente Proer shoul be only a small aition to the regular training. The current prouct evelopment project at TNO-FEL has starte with the escription of the scenarios in which the Instrumente Proer may be use an the evelopment of user requirements, base on input from a Users Group (see section ). Base on these scenarios an user requirements, a test plan was evelope for the current technology emonstrator version uner controlle conitions as escribe in section. The test set-up,

2 incluing the force applying mechanism, the targets use in these tests, test proceure an the test results are presente in section 4. In section 5, an outlook of the work in the remainer of the current project is presente, as well as the continuation of the project evelopment path to a market-reay evice.. Scenarios an User Requirements As a first step in the current prouct evelopment, the scenarios for emining operations in which an Instrumente Proer may be applie, are establishe. The starting point was the escription of the emining scenarios provie in a recent report by the Geneva International Center for Humanitarian Demining [7]. The use of the Instrumente Proer will be limite to scenarios with soft to meium soil harness. However, ue to the force feeback mechanism, it is possible that the Instrumente Proer may be use more safely in meium-har soil than the conventional proer. Special attention was given to the question of the surplus value of the Instrumente Proer in emining operations, assuming that this evice performs well an reliable. In current humanitarian emining operations the conventional proer is often use in conjunction with a metal etector. Normally, when the latter inicates the presence of metal, the operator uses the proer to obtain information on the epth, size, shape an orientation of the (metal-containing) object before attempting to safely excavate the object. In most cases the aitional information from the Instrumente Proer concerning the type of material of the object s surface will not be of much use for the eminer. He will instea rely exclusively on the metal etector s alarm an procee to excavate the object in orer to remove the metal part that gave the alarm. A similar situation applies for the case where the Instrumente Proer is use in conjunction with a emining og. However, in conitions where a metal etector can t be use an other emining equipment, like ogs, is not reaily available, the Instrumente Proer may lea to faster an safer emining. One can think of emining near houses or other structures with reinforce concrete, near railways, uner powerlines, etc. With input from the Users Group, the user requirements for an Instrumente Proer can be summarize as follows. The emphasis lies on robustness an on the user interface. It is require that the Instrumente Proer can also be use as a conventional proer in operations where the force feeback an material inication are not consiere avantageous.. Technology Demonstrator The current version of the Instrumente Proer can be regare as a 'technology emonstrator'. The feasibility of a proer with force feeback an material inication can be emonstrate with this version. However the evice as constructe in this version is not intene nor suitable for fiel testing uner less than perfect conitions. The Instrumente Proer has two integrate sensors, a loa cell to measure the force exerte by the operator an a piezoelectric crystal for sening an receiving ultrasonic pulses through the proer's shaft. Combining the transmitte an reflecte pulses, the material uner contact with the tip of the proer can be ientifie. The proer is tethere by a cable to a box that houses the power supply (batteries) an electronics for signal processing (see Figure 1). The box is equippe with a RS connector for igital recoring of the loa cell output an the material ientification signal ( ecision signal ). The present technology emonstration version is not equippe with an auio output. Two samples were available for testing. Figure 1 Technology emonstrator version of the Instrumente Proer 4. Tests uner Controlle Conitions The technology emonstrator version of the Instrumente Proer was teste uner controlle conitions to assess its capability of ientifying the casing material of burie objects. The objects were burie in several soils with varying properties. Prior to the execution of the tests, a test plan was written. The test plan escribe the test facility, test objects, test proceure an aitional measurements. The force use to push the proer into the soil was controlle, as well as the angle of the proer with the soil surface. The ecision signal of the Instrumente Proer was assesse an recore by an operator uring the tests Test Set-up The tests were execute at the outoor test facility of TNO-FEL in The Hague, The Netherlans. This test facility consists of six test lanes with a length of 1 m,

3 with of m an epth of 1.5 m. The six lanes contain san, clay, peat, iron-containing soil (ferruginous soil), woolan soil an a grass layer, respectively. Figure shows a picture of the test facility. On the test facility a xy-positioning frame is present (see Figure ). Aitional information on the test lanes can be foun in [8]. coul apply a maximum force of 15 N. This motor was riven by a power supply with current limitation. A calibration table was use to set the current for the chosen force. However, uring preliminary tests it became clear that larger forces than 15 N were require to insert the Instrumente Proer in most soil types present in the six test lanes. For that reason the motor was replace by a manually operate spinle with a gearwheel (see Figure ). During insertion, the exerte force on the proer was shown on the isplay of a laptop computer using a locally create program. The program also create a log file in which the measure force an the result of the material ientification algorithm (i.e. the ecision signal) were recore. The same laptop computer was also use to operate the Instrumente Proer where control characters were sent to the proer to set the various moes of operation: calibration of the loa cell in air; ion for the loa cell s offset; an starting the material ientification algorithm. Figure TNO-FEL outoor test facility During the test perio (April 14-1, ), the harness an the moisture content of the top layer (up to 1 cm eep) of the six lanes were measure with a penetrometer an a Time Domain Reflectometer (TDR). The results of these measurements are given in Table 1, together with other relevant ata of these soils. Table 1 Soil type Soil ata Sa n Cla y Pea t Fer rug ino us W oo l an Gr ass lan Harness (Pa) Moisture content 4.4% % 9% 1% 15% % Dry matter n.a. ensity (kg/m ) Organic matter < 1% % 5% % 5% n.a. content Lutum content < % 7% 15% % % n.a. The Instrumente Proer was mounte on the measurement platform of the xy-positioning frame in such a way that it coul be force into the soil at the angles of, an 9. Since the material-ientification algorithm implemente in the Instrumente Proer is esigne to perform optimally for contact forces in the range of to 11 N (see [5]), a DC motor was selecte that Figure Instrumente Proer mounte on the measurement platform 4.. Test Objects In orer to assess the material ientification feature of the Instrumente Proer, seven ifferent types of objects were burie in each of the six test lanes at a epth of 5 cm (i.e. the istance of the top of the object to the soil surface). These objects are: - Inert PMN mines (fuzes remove an the explosive replace by silicon rubber RTV11 from Dow Corning.);

4 - Soli cyliners of pouring concrete (1 cm iameter, 5.5 cm height), with a smooth surface; - Bricks with a rough surface (sies of 11 cm, cm height); - Soli aluminium cyliners with a iameter of 1 cm an height of 5.5 cm; - Soli PVC cyliners with a iameter of 1 cm an height of 5.5 cm; - Soli cyliners (1 cm iameter, 5.5 cm height) from fir; - Soli steel cyliners (1 cm iameter, 5.5 cm height). Because only four inert PMN mines were available, no inert PMNs were burie in the lanes with san an clay. Figure 4 shows samples of the seven object types. The test objects were burie along a straight line parallel to the long sies of the lanes an at intermeiate istances of 5 cm. All objects were burie in such a way that the axis of the cyliner was oriente vertically. The positions of the burie objects were inicate with a marker (skewer) to facilitate the etermination of the proing positions. tip was in contact with the burie object, he lowere the force to 1 N, recore the material inication from the laptop s isplay, lowere the force to 5 N an again rea off the material inication. 4. If necessary, the neele of the proer was cleane with a cloth after the shaft was remove from the groun. In aition, the output of the loa cell an the ecision signal were recore igitally uring all proing actions for future analysis. Figure 5 shows the Instrumente Proer uner test. On each burie object, proing actions were performe: one on the center of the object an two 4 cm out of the center. In total 88 proing actions were performe; 9 per proing angle. Figure 5 Instrumente Proer uner test. Proing angle is. Figure 4 Seven types of objects use in the tests 4.. Test Proceure The test proceure consiste of a number of steps for a proing action on a single test object which can be summarize as follows: 1. After calibration of the loa cell an ion for the loa cell s offset, the measurement platform with the mounte Instrumente Proer was move manually to the proing position. This position (relative to the test object) epene on the chosen proing angle. Angles of, an 9 were use.. The proer was force into the soil uner the chosen angle with a force up to 5 N by spinning the gearwheel manually. The actual force was inicate in real-time on a laptop s isplay present on the measurement platform. Hence the operator was able to control the force by han.. When the operator was confient that the proer s 4.4. Test Results For the tests, two samples of the Instrumente Proer s technology emonstration version were available. However, ue to technical problems, the tests on all six lanes an for all three proing angles (, an 9 ) were fully complete by only one of the proers. Only the results of the sample that went through the complete test are reporte here. In Table the results for the material ientification of the Instrumente Proer per soil type are shown. The results for the three proing angles an the two contact forces (5 an 1 N) are tallie up in this table. From Table it is clear that the material ientification feature of the Instrumente Proer s technology emonstration version is not functioning reliably uner all test conitions. There appears to be no correlation between the harness of the soil consiere (see Table 1) an the material ientification performance. In 8 proing actions, the proer s tip i not make contact with the burie object. This happene only twice for the 9 proing angle.

5 Table shows the test results for peat an woolan soil when proing with an angle of 9. The results for the contact forces of 5 an 1 N are tallie up in this table. Table Soil type Test results Sa n Object/Result Metal Rock Plastic/Woo Cla y Pea t Fer rug ino us W oo l an Gr ass lan 7 9 Table Test results for a proing angle of 9 in peat an woolan soil Soil type: Peat Woolan Object/Result: Metal Rock Plastic/Woo The results shown in Table inicate that material ientification of burie objects is feasible with the technology implemente in the Instrumente Proer. However, comparison of the test results for the ifferent soil types an proing angles clearly show that the performance of the material ientification feature of the technology emonstrator epens strongly on the test conitions. The technology emonstrator performs unreliable for proing angles of an an in san, clay, ferroginous soil an grasslan. This suggests that the performance is egrae when the proer s neele is inserte eeply into the soil in orer to make contact with the burie object. It also appears that performance is reuce when the evice is use in sticky soil. This behaviour may be explaine by the notion that the loa cell measures not only the force on the proer s tip (ue to the soil to be penetrate or the object that is contacte), but also the friction force on the inserte part of the neele. This friction force may ominate the loa cell output when the neele is far enough in the soil an the soil is sticky. Since the loa cell output is essential for the material ientification algorithm, a significant friction force contribution to the loa cell output will result in an material ientification. Another possibility to consier is that the ultrasonic pulses may be attenuate by material that sticks to the proer s shaft. This may lower the signal to noise ratio an confuse the ientification algorithm. 5. Conclusion The material ientification performance of the Instrumente Proer s technology emonstrator has been assesse by tests conucte uner controlle conitions. The results of these tests show that material ientification of burie objects is feasible with the implemente technology. The large percentage of material ientifications in four of the six soil types use in the tests an for proing angles that necessitate eeper insertion of the proer s neele for contact with the burie object, are probably ue to friction forces on the proer s neele an possible signal attenuation. To increase the reliability of the material ientification feature to the level that is necessary for operational use of the Instrumente Proer, the mechanical esign an the implementation of the sensor use to measure the applie force shoul be reconsiere. If this reliability level is reache, esign aspects like robustness an user interface shoul be looke at in close collaboration with potential en users in orer to procee with the prouct evelopment. Besies further technical evelopment of the Instrumente Proer, it is essential to efine the ae value of such a system to the current emining tool box, the scenarios in which it can be use successfully, an the performance limitations. Acknowlegments The authors woul like to thank the Royal Netherlans Army for funing the project, the Canaian Centre for Mine Action Technology an HF Inc for support an the members of the Users Group for valuable input an comment.. References [1] K. Russell, Contact methos, in: Alternatives for lanmine etection, e.s J. MacDonal et al., ISBN -

6 [] U.S. Army Communications an Electronics Comman, NVESD, Fort Belvoir, "Operational Capabilities Demonstration an Test Report: Smart Mine Probe", August [] D. Melville, User Evaluation Report Smart Probe Instrumente Proer, Lan Forces Trials an Evaluation Unit, PO Box 17, Stn Forces, Oromocto, NB, Canaa, EV 4J5, October [4] R. Gasser, "Feeback Proers: A Training Tool to Improve Deminer Safety'', Journal of Mine Action, 5.. [5] R. Gasser, "Technology for Humanitarian Lanmine Clearance", PhD thesis, University of Warwick, September. [] K. Russell, "September 1 test results of an acoustic instrumente proer", The UXO/Countermine Forum, Orlano FL, U.S.A., September. [7] Mine action equipment: stuy of global operational nees, GICHD, June. [8] Wim e Jong, Henk A. Lensen, Yvonne H.L. Janssen, "Sophisticate test facility to etect lan mines", in: Detection an Remeiation Technologies for Mines an Minelike Targets IV, Proceeings of SPIE Vol. 71, (1999).