Industrial robot arms

A robot arm or the like, comprising:

• A. a base;
• B. an arm having a first end which is pivotable relative to said base about a first pivot to define a shoulder and a second end, wherein said arm is articulated to define an upper arm, a lower arm, and an elbow pivotally connecting said upper and lower arms at a second pivot;
• C. a support having a first end which is pivotable relative to said lower arm about a third pivot to define a wrist and a second end;
• D. shoulder flexing apparatus for moving said support to a desired location relative to said base;
• E. wrist flexing apparatus operating in coordination with said shoulder flexing apparatus for translating said support relative to said base without rotating said support, said wrist flexing apparatus comprising:
• i. a first sprocket fixed to said base in coaxial relation to said first pivot;
• ii. a second sprocket fixed to said support in coaxial relation to said third pivot;
• and
• iii. third and fourth coaxial sprockets fixed to each other, mounted coaxially with said second pivot, and freely rotatable with respect to said upper and lower arms;
• I. a first drive chain operatively connecting said first and third sprockets;
• and
• J. a second drive chain operatively connecting said second and fourth sprockets.

A drive mechanism for alternately rotating a first member and a second member in the same direction with respect to a third member or in opposite directions about the third member, said mechanism comprising:

• A. a planetary gear set comprising a sun gear, a planet carrier supporting planet pinions for rotation about said sun gear in meshed relation thereto, and an internally toothed annulus concentric with said sun gear and meshed with said planet pinions;
• B. first drive/lock means for selectively rotating or locking one of said annulus and said sun gear with respect to the third member;
• C. drive means for rotating the second member responsive to rotation of the other of said sun gear and said annulus.
• D. second drive/lock means for selectively rotating or locking said planet carrier with respect to the first member;
• and
• E. third drive/lock means for selectively rotating or locking said first member with respect to said second member.