Embodiments relate to robotic arm assemblies. Embodiments include shoulder segment and upper arm segment having motor drive portion. Embodiments include shoulder coupling joint assembly connecting upper arm segment to shoulder segment. Shoulder coupling joint assembly includes distal shoulder joint subassembly connected to upper arm segment. Distal shoulder joint subassembly includes distal shoulder joint forming first axis. Distal shoulder joint subassembly includes shoulder planetary gear assembly having shoulder sun gear configured to rotate relative to first axis when motor drive portion is driven to rotate. Shoulder planetary gear assembly includes shoulder planetary gear carrier. When shoulder sun gear rotates, shoulder planetary gear carrier drives upper arm segment to rotate relative to first axis. Shoulder coupling joint assembly includes proximal shoulder joint subassembly connecting shoulder segment to distal shoulder joint subassembly. Proximal shoulder joint subassembly includes proximal shoulder joint forming second axis, which rotates distal shoulder joint subassembly relative to second axis.
