New Oz cam­ou­flage sys­tem can in­stantly change a ve­hi­cle’s colour

The Witness - Wheels - - TRANSPORT -

AT the Land Forces con­fer­ence in Ade­laide, Aus­tralia, ear­lier this month, a devel­op­ment in mil­i­tary tech was pre­sented that brings auto-cam­ou­flag­ing tanks a step closer to re­al­ity.

To find out more about the tech­nol­ogy be­hind the idea, we asked Peter Mur­phy from the Univer­sity of South Aus­tralia (UniSA), to ex­plain what goes into mak­ing a colour-chang­ing mil­i­tary tank. He an­swered as fol­lows. “The con­cept of colour-chang­ing tanks, able to change their cam­ou­flage pat­tern in real time in the bat­tle­field to adapt to chang­ing sur­round­ings, is one of the holy grails of mod­ern mil­i­tary de­cep­tion.

“Even in the mod­ern the­atre of war, pre­vent­ing ini­tial de­tec­tion by the hu­man eye is the pri­mary goal in de­ceiv­ing the en­emy.

“The lim­i­ta­tion of present cam­ou­flage tech­nol­ogy is that it is gen­er­ally a static sys­tem that has been painted onto the struc­ture it is pro­tect­ing.

“Such cam­ou­flage pat­terns come in a va­ri­ety of forms to typ­i­cally suit ei­ther wood­land, desert or snow-based en­vi­ron­ments. Adap­tive cam­ou­flage would have the ca­pa­bil­ity to work across all of these en­vi­ron­ments, much like a chameleon or oc­to­pus is able to change colour to suit the sur­round­ings it is in.

“A group of re­searchers from the Univer­sity of South Aus­tralia’s Fu­ture In­dus­tries In­sti­tute has been work­ing in part­ner­ship with sci­en­tists from Aus­tralia’s De­fence Sci­ence and Tech­nol­ogy Group [DST Group] on de­vel­op­ing adap­tive cam­ou­flage us­ing ma­te­ri­als known as con­duct­ing poly­mers.

“These ma­te­ri­als are ef­fec­tively plas­tics that con­duct elec­tric­ity.

“By ap­ply­ing a very thin coat­ing of these ma­te­ri­als to a sur­face and sur­round­ing them with an elec­trolyte, it is pos­si­ble to make them change colour when a volt­age is ap­plied to them. By us­ing con­duct­ing poly­mers with vary­ing chem­i­cal struc­tures, dif­fer­ent colour changes can be achieved.

“The con­duct­ing poly­mers and elec­trolyte are housed in a trans­par­ent sand­wich-like struc­ture (the elec­trochromic cell) that is sealed around the edges. The faces of the cell can be made out of var­i­ous ma­te­ri­als rang­ing from glass to poly­car­bon­ate or even Pet (poly­eth­yl­ene tereph­tha­late), which is the ma­te­rial pre­vi­ously used to make over­head trans­parency sheets.

“Key to mak­ing this tech­nol­ogy work in the real world is to en­sure that the elec­trochromic cells are ro­bust and light­weight. It is not un­rea­son­able to ex­pect the elec­trochromic cells to func­tion in a tem­per­a­ture range from -40 de­grees Cel­sius to 80 de­grees Cel­sius, which is the re­quire­ment for parts pro­duced for the au­to­mo­tive in­dus­try. The elec­trochromic cells also need to be able to sur­vive shock, abra­sion dam­age and be sta­ble in UV light.

“The cur­rent re­search at UniSA is fo­cused on de­vel­op­ing light­weight flex­i­ble elec­trochromic cells up to 20x20 cm. These cells are able to be fixed to the out­side of a tank (us­ing strong dou­blesided ad­he­sive) and are wired to­gether and con­nected to a bat­tery for power sup­ply.

“In a fully func­tion­ing sys­tem, you would use cam­eras that would au­to­mat­i­cally sense the sur­round­ings/back­ground and then ad­just the elec­trochromic cam­ou­flage cells to suit.

“The colour change could oc­cur over a time frame rang­ing from a few sec­onds to sev­eral tens of sec­onds. The rate of colour change can be ad­justed to the level re­quired. That is, it can be in­creased or de­creased ac­cord­ing to the speed of the ve­hi­cle. A to­tal colour change can be achieved in as lit­tle as one sec­ond if re­quired.

“Us­ing this tech­nol­ogy, the colour­change pat­tern is de­ter­mined by the coat­ing process used to fab­ri­cate the cells. It is highly likely that a ro­botic spray-coat­ing process would be used to pro­duce the elec­trochromic cells at a com­mer­cial level. Such a process is amenable to pro­duc­ing both block colour pat­terns and also com­plex pat­terned cells. In re­al­ity, the abil­ity to pro­duce com­plex pat­terns is likely to be most use­ful, as it would al­low a de­gree of com­plex­ity to the pat­terns that would aid with the de­cep­tion process.

“Our most re­cent pro­to­type cells in­deed fo­cus on pro­duc­ing com­plex pat­terns, with changes in colour and colour in­ten­sity within a cell.

“To date, we have only tested small ar­rays of the cells (such as those shown in the photo) and have re­cently com­pleted tran­si­tion­ing the tech­nol­ogy from glass to poly­car­bon­ate cells — halv­ing the weight of the sys­tem.

“The next stage of the project will see the tech­nol­ogy evolve to fully flex­i­ble cells able to be bent over an edge or cor­ner as you would find on ve­hi­cles.

PETER MUR­PHY Pro­fes­sor at UniSA A to­tal colour change can be achieved in as lit­tle as one sec­ond if re­quired.

PHOTO: AUS­TRALIAN ARMY CULTANA TRAIN­ING FA­CIL­ITY, DE­FENCE SCI­ENCE AND TECH­NOL­OGY GROUP

A re­searcher shows the var­i­ous tank colours that can be achieved with an elec­tri­cal cur­rent.

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