Robust Sliding Mode Control Based on GA Optimization and CMAC Compensation for Lower Limb Exoskeleton

<div>Prototype of lower limb powered exoskeleton. There are two active joints of each leg in walking direction, which are represented as <svg height="14.589pt" id="M1" style="vertical-align:-5.30067pt" version="1.1" viewbox="-0.0498162 -9.28833 19.0186 14.589" width="19.0186pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M475 507C475 612 440 712 326 712C139 712 23 420 23 215C23 96 58 -12 180 -12C369 -12 475 293 475 507ZM391 522C391 486 387 448 379 394H126C155 538 222 677 310 677C386 677 391 571 391 522ZM373 346C344 193 283 22 189 22C126 22 106 114 106 196C106 243 111 293 118 346H373Z" id="g113-230"></path><glyph.data ascent="3473" descent="-2876" horiz-adv-x="498" vert-adv-y="498"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,6.149,3.132)"><path d="M522 0V30C462 35 455 41 455 106V280C455 397 397 451 314 451C262 451 206 414 171 379V710C131 698 69 682 20 675V647C87 642 90 637 90 574V106C90 41 80 35 20 30V0H236V30C176 35 171 43 171 106V339C198 371 237 391 276 391C341 391 374 350 374 269V106C374 43 367 35 308 30V0H522Z" id="g58-102"></path><glyph.data ascent="1007" descent="-369" horiz-adv-x="544" vert-adv-y="544"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,11.099,3.132)"><path d="M138 535C169 535 191 560 191 589C191 620 168 644 139 644S85 620 85 589C85 560 110 535 138 535ZM257 0V30C192 35 185 43 185 109V453C142 435 94 422 40 414V386C101 378 104 372 104 311V109C104 41 97 35 33 30V0H257Z" id="g58-103"></path><glyph.data ascent="1007" descent="-369" horiz-adv-x="275" vert-adv-y="275"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,13.492,3.132)"><path d="M173 382V461C125 442 68 425 25 418V390C88 382 92 382 92 317V-127C92 -191 84 -199 18 -204V-235H259V-204C180 -196 173 -192 173 -120V7C188 -1 212 -11 243 -12C375 12 495 109 495 261C495 361 427 451 316 451C303 451 283 446 266 435L173 382ZM173 345C200 365 243 388 274 388C346 388 409 329 409 222C409 111 353 40 266 40C231 40 196 56 173 79V345Z" id="g58-110"></path><glyph.data ascent="1007" descent="-369" horiz-adv-x="534" vert-adv-y="534"></glyph.data></g></svg> and <svg height="12.584pt" id="M2" style="vertical-align:-3.29567pt" version="1.1" viewbox="-0.0498162 -9.28833 24.6086 12.584" width="24.6086pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M475 507C475 612 440 712 326 712C139 712 23 420 23 215C23 96 58 -12 180 -12C369 -12 475 293 475 507ZM391 522C391 486 387 448 379 394H126C155 538 222 677 310 677C386 677 391 571 391 522ZM373 346C344 193 283 22 189 22C126 22 106 114 106 196C106 243 111 293 118 346H373Z" id="g113-230"></path><glyph.data ascent="3473" descent="-2876" horiz-adv-x="498" vert-adv-y="498"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,6.149,3.132)"><path d="M523 0V30C483 33 455 48 422 83C390 115 285 234 266 263C309 314 327 333 351 357C388 392 414 404 483 415V444L273 435V405C320 400 321 392 302 364C285 339 256 300 233 277C218 262 201 250 170 243V710C130 697 73 680 22 675V647C85 642 89 637 89 570V107C89 44 83 35 14 30V0H244V30C179 35 170 41 170 107V214C176 216 181 217 186 217C194 217 203 212 216 196C273 129 333 54 384 -1L523 0Z" id="g58-105"></path><glyph.data ascent="1007" descent="-369" horiz-adv-x="507" vert-adv-y="507"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,10.936,3.132)"><path d="M532 0V30C473 38 467 38 467 107V298C467 395 416 451 336 451C307 451 279 439 251 420C226 404 205 389 185 374V453C142 434 94 422 43 413V386C98 378 104 373 104 309V107C104 41 100 38 31 30V0H251V30C191 35 185 40 185 107V337C216 364 255 389 295 389C360 389 386 347 386 276V110C386 44 380 35 321 30V0H532Z" id="g58-108"></path><glyph.data ascent="1007" descent="-369" horiz-adv-x="557" vert-adv-y="557"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,15.978,3.132)"><path d="M384 109C349 76 310 59 268 59C197 59 123 113 120 245C240 248 367 259 384 262C403 266 407 275 407 296C407 376 338 451 254 451H253C201 451 148 425 105 378C65 334 39 272 39 203C39 88 112 -12 235 -12C266 -12 339 5 402 84L384 109ZM230 411C285 411 319 365 319 313C319 298 313 293 294 293C236 291 180 290 125 290C141 370 185 411 230 411Z" id="g58-99"></path><glyph.data ascent="1007" descent="-369" horiz-adv-x="434" vert-adv-y="434"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,19.972,3.132)"><path d="M384 109C349 76 310 59 268 59C197 59 123 113 120 245C240 248 367 259 384 262C403 266 407 275 407 296C407 376 338 451 254 451H253C201 451 148 425 105 378C65 334 39 272 39 203C39 88 112 -12 235 -12C266 -12 339 5 402 84L384 109ZM230 411C285 411 319 365 319 313C319 298 313 293 294 293C236 291 180 290 125 290C141 370 185 411 230 411Z" id="g58-99"></path><glyph.data ascent="1007" descent="-369" horiz-adv-x="434" vert-adv-y="434"></glyph.data></g></svg>. All auxiliary facilities are packaged in the backpack.</div>

Applied Bionics and Biomechanics

fig1

Figure 1

Figure 1: Robust Sliding Mode Control Based on GA Optimization and CMAC Compensation for Lower Limb Exoskeleton 