Check out robotic part and legs 3D model on CGTrader for $9. High-quality mesh by izydor-template.
STL (Stereolithography, filesize: 16.3 MB), OBJ (OBJ, filesize: 33.8 MB), FBX (Autodesk FBX, filesize: 35.7 MB), STP (STEP, filesize: 31.3 MB), 3DS (3D Studio, filesize: 5.86 MB)