Iinkqubo zokuqhuba ze-Mecanum (drivetrains) ziyatyibilika ngexesha leenkqubo ezizisebenzelayo (autonomous routines) ze-FTC ngenxa yokuba ukuhamba kwazo kuxhomekeke ekurhoxisaneni ngokuchanekileyo ngokwezibalo kwamandla e-vector axwesileyo ane-engile engama-45 degrees. Kwiithayile ze-EVA foam ezithambileyo nezingalinganiyo, amandla aqhelekileyo (normal forces) angalinganiyo kunye nokutyibilika kwee-roller kuthintela ezo vectors ekubeni zilungelelane ngokugqibeleleyo, nto leyo edala ukujikeleza okungafunekiyo (yaw) okwanda ngokomgama. Awudingi ii-odometry pods ezingenawo amandla nezibiza kakhulu (dead wheels) ukulungisa oku: ungaphelisa uninzi lweempazamo zokuhamba kwi-autonomous ngokuvala i-loop kwicala elijoliswe kulo (heading) usebenzisa i-IMU eyakhelwe ngaphakathi kwi-REV Control Hub kunye nokunciphisa ukukhawulezisa ukuze uhlale ngaphakathi kwemida yokukhuhlana (static friction) kwee-roller zakho.

Ubuxhakaxhaka bokuTyibilika kwe-Mecanum

Ivili eliqhelekileyo lokutsala (traction wheel) lisebenzisa amandla ahambelana nokujikeleza kwevili. Ivili le-Mecanum lidlulisela amandla nge-roller ezingasebenziyo (passive rollers) ezine-engile engama-45 degrees xa zithelekiswa nepleyiti yevili. Xa imoto ijikelezisa ivili le-Mecanum phambili, indawo edibanayo ivelisa i-vector exwesileyo: inxalenye enye ityhalela irobhothi phambili, kunye nenxalenye elinganayo etyhalela ecaleni.

Ukuze iqhubele phambili ngqo, amavili angasekhohlo nangasekunene asebenzisa amandla athe tyaba (transverse forces) alinganayo naphikisanayo arhoxisanayo, ashiye kuphela amandla okuqhubela phambili. Ukuze itshintshele ecaleni ngqo (strafe), amapheya axwesileyo aphikisanayo ajikeleza ngokuchasene namanye, erhoxisa amandla okuqhubela phambili aze adibanise amandla asecaleni.

Oku kurhoxiswa kwee-vector kuthatha ukuba kukho iimeko ezintathu ezingaze zibe yinyani kwibala lokhuphiswano:

• Amandla aqhelekileyo alinganayo (Symmetric normal forces): Ukuba umbindi wobunzima berobhothi yakho (centre of mass) uthe waxwesa kancinci ukuya kwibhetri okanye kwindlela yokuphakamisa, iikona ezinzima zifumana amandla aqhelekileyo aphezulu kunye nokutsala okungakumbi. Iikona ezikhaphukhaphu ziyatyibilika, zishiye amandla asecaleni engarhoxiswanga.
• Ukutsala okufanayo komphandle (Uniform surface traction): Iithayile ze-EVA foam ezithambileyo nezitshixanayo ziyagoba phantsi kobunzima. Ii-roller zitshona kwi-foam kubunzulu obungafaniyo, zitshintsha i-engile yokudibana nenkcaso yokugingqa (rolling resistance) ukusuka kwi-millisecond ukuya kwenye.
• Ukukhuhlana okuhambayo okufanayo (Identical kinetic friction): Ii-roller zeplastiki nerabha eziqhelekileyo kumavili e-Mecanum athengiswayo zineeyantlukwano ezincinci zokwenziwa, ukuxega kwi-axis (axial play), kunye neeyantlukwano zokukhuhlana kwangaphakathi.

Xa ii-vector zamandla zisilela ukurhoxisana ngokugqibeleleyo, umphumela okhawulezileyo yi-yaw torque engayalelwanga. Xa irobhothi yakho ijikeleza ngeedigri ezimbini okanye ezintathu nje ukusuka kwicala ebelijoliswe kulo, i-tick nganye elandelayo ye-motor encoder iqhuba irobhothi kwindlela ejikeleziweyo, isandisa iimpazamo zendawo ngokuhamba kwexesha.

Isisombululo: Ukulungisa Indlela Ngokusebenzisa i-IMU (Active IMU Heading Correction)

Ngelixa ii-encoder zeemoto zikala ukuba ii-shaft zamavili zijikeleze kangakanani, azikwazi ukukala ukutyibilika kwee-roller kumgangatho. Nangona kunjalo, awudingi ukulandelela indawo ye-Cartesian ngokupheleleyo ukusombulula uninzi lweempazamo zakho ze-autonomous. Ukuba uthintela irobhothi ekubeni ijikeleze isuke kwicala layo elijoliswe kulo, iimpazamo ze-encoder zokuhamba ngokuthe ngqo (translational) zihlala zithe ngqo kwaye zinokuqikelelwa endaweni yokuba zijikeleze kwaye zibe yintlekele.

I-REV Control Hub nganye iqulethe i-Inertial Measurement Unit (IMU) yangaphakathi ekwaziyo ukufunda ulwalathiso lwe-engile olupheleleyo (yaw) ngokuchaneka okuphezulu nokutyibilika okuncinci kwithuba le-autonomous lemizuzwana engama-30.

Ukumilisela i-Heading Lock Loop

Endaweni yokuthumela amandla ahambisayo angacocwanga ngqo kwiimoto zakho zokuqhuba, dlulisa impazamo yakho yecalelo (heading error) nge-Proportional-Derivative (PD) control loop efaka amandla okulungisa ukujikeleza kwii-equation ze-kinematic ze-Mecanum ngexesha langempela.

Ii-equation ze-kinematic eziqhelekileyo ze-Mecanum zamandla eemoto zezi:

• Front Left = Drive + Strafe + Turn
• Front Right = Drive - Strafe - Turn
• Back Left = Drive - Strafe + Turn
• Back Right = Drive + Strafe - Turn

Kwinkqubo evulekileyo (open-loop routine), Turn isetwe ku-zero ngexesha lokuqhuba ngqo okanye ukutshebeleza ecaleni (strafes). Kwinkqubo etshixwe kwicala esebenzayo (active heading-locked routine), Turn ibalwa ngokutshintshayo ukusuka kwimpendulo ye-IMU yaw kuphindaphindo ngalunye lwe-loop:

1. Funda indlela yangoku (Read current heading): Fumana i-engile ye-yaw yangoku kwi-IMU.
2. Bala impazamo yendlela (Calculate heading error): Bala umahluko omfutshane we-engile phakathi kwendlela ojoliswe kuyo nendlela yakho yangoku, uqinisekise ukuba uqhelekisa (normalize) i-engile phakathi kwe -180 kunye ne +180 degrees (okanye -π kunye ne +π radians) ukuthintela iimpazamo zokugqwetheka (wrap-around errors).
3. Bala ulungiso (Calculate correction): Phinda-phinda impazamo nge-proportional gain (kP) elungisiweyo, uze udibanise izinga lotshintsho lwempazamo eliphindaphindwe nge-derivative gain (kD) ukunciphisa ukugungqa (oscillations).
4. Faka kwaye uqhelekise (Apply and normalize): Faka eli xabiso lolungiso kwisiguquki (variable) esingu-Turn. Ukuba kukho ubalo lwemoto oludlula amandla ka-1.0 (okanye -1.0), yahlula onke amandla eemoto zone ngelona xabiso lipheleleyo liliphezulu (maximum absolute value) ukugcina imilinganiselo ye-vector ecwangcisiweyo ngaphandle kokunqunyulwa.

Ukuqhelekisa (normalising) amandla eemoto kubaluleke kakhulu. Ukuba irobhothi yakho iqhuba phambili ngamandla apheleleyo kwaye umlawuli ufuna ulungiso lokujika, ukunqunyulwa okungaqhelekiswanga kuya kuyicima inkqubo yolungiso kwaye kuvumele irobhothi ukuba ityibilike nokuba izibonelelo zakho zesoftware (software gains) zithini na.

Ukulawula ukuTyibilika kwe-Kinetic ngokuCothisa iSantya (Slew Rate Limiting)

Ulungiso olusebenzayo lwendlela lulawula ukukhukuliseka kokujikeleza, kodwa ukukhawulezisa ngokukhawuleza kubangela ukutyibilika kwexesha elide nasecaleni apho amavili ajikeleza ngokukhawuleza kunokuba i-chassis ikhawulezisa. Xa ii-roller ziphulukana nokubamba okuthe ngqo kwi-foam, ii-encoder zeemoto zibhalisa umgama ongazange uhanjwe.

Ukulungisa ukutyibilika kwe-kinetic ngaphandle kwee-dead wheels:

• Nciphisa uKhawuleziso (Slew Rate): Ungaze utsibe amandla ekujoliswe kuwo emoto ukusuka ku-0.0 ukuya ku-1.0 kumjikelo omnye we-loop. Nyusa amandla ngokuthe ngcembe usebenzisa isinciphisi santya esilula (umz., ukumisa ukukhawulezisa ekunyukeni okungekho ngaphezulu kwamandla angama-0.05 kumjikelo ngamnye wemizuzwana engama-20).
• Cothisa nge-Profile (Decelerate with a Profile): Sebenzisa iprofayili yesantya ye-trapezoidal okanye ye-S-curve ukucothisa irobhothi ngaphambi kokuba ifikelele kwinani le-encoder ekujoliswe kulo. Ukubhuleka ngesiquphe kubangela ukuba irobhothi ityibilike phezu kweethayile, nto leyo eyonakalisa indawo ekumiswa kuyo ekujoliswe kuyo.
• Uqhagamshelwano loMgangatho woBuxhakaxhaka (Mechanical Floor Contact): Qinisekisa ukuba i-chassis ye-drivetrain yakho inokuthotyelwa kancinci kwe-torsional okanye i-rocker suspension kwi-axle enye. Ukuba i-chassis eqinileyo yamavili amane idibana nomthungo ongalinganiyo phakathi kweethayile ze-foam, ivili elinye liyaphakama kancinci kumgangatho, liphulukane nokutsala ngoko nangoko kwaye libangele ukutyibilika.

Zifuneka Nini Ngokwenene ii-Dead Wheels?

Amaqela adla ngokukhawuleza asebenzise ii-odometry pods ezinamavili amathathu anee-springs ngenxa yokuba ekholelwa ukuba amavili e-Mecanum akanakuhamba umkhondo we-autonomous othembekileyo wemizuzwana engama-30. Enyanisweni, i-heading lock loop elungiswe kakuhle edityaniswe nokunyusa isantya okusekelwe kwi-encoder yanele ukufumana amanqaku kwimisebenzi yexabiso eliphezulu ye-autonomous, ukulungelelanisa ngokuthembekileyo neendonga zebala, kunye nokupaka ngokufanayo.

I-odometry yee-dead-wheels ifuneka kuphela xa iqhinga lakho le-autonomous lifuna iindlela ezintsonkothileyo, ezinesantya esiphezulu ze-spline ezineendawo ezininzi (njengee-trajectory ezipheleleyo ze-Road Runner okanye ze-Pedro Pathing) apho irobhothi kufuneka yazi uququzelelo lwayo oluchanekileyo lwe-(X, Y) emva kokungqubana nezinto zomdlalo okanye ukutshebeleza ngamandla kuwo wonke ububanzi bebala.

Ukuba wakha kwaye uphucula ii-drivetrain ze-FTC okanye ujonge ukuba yingcali kwi-autonomous motion profiling neqela lakho, jonga izikhokelo zethu zobunjineli bokhuphiswano apha Sheen Robotics FTC Resources.