Patent GB-1464952-A (GB)
Title: Industrial robots
IPC: B25J9/06
Filed: 1974-03-15
Abstract: 1464952 Manipulator DAIKIN KOGYO CO Ltd 15 March 1974 [17 March 1973] 11724/74 Heading B8H [Also in Division F2] A robot comprises an articulated arm A with pivotally connected equal length sections A 2 , A 3  coupled by epicyclic gear trains Ec, Ed such that they may pivot by equal amounts but in opposite directions to achieve a stretching or retraction of the arm or they may pivot together as if rigidly connected. A grasping arm A 4 , which mounts a fluid operated grasp A 5 , is pivotally mounted on the arm section A 3  and is coupled to the arm sections by further epicyclic gear trains whereby the absolute angular disposition of the arm A 4  about the pivotal axis B 4  between the arm A 4  and the arm section A 3  and about longitudinal axis of the arm is maintained constant or varied regardless of the pivotal motion of the arm sections A 2 , A 3 . The robot has a fixed base block X with a swivel base block Y mounted thereon for rotation about a vertical axis. A first joint shaft B 1  is rotatably mounted in the base block Y and has a first pair of arms A 1  fixed thereto. In addition a sun gear Sd and a drive gear C are rotatably mounted thereon and a drive gear D is fixed thereto. The sun gear Sd meshes with a planet gear P 1 d, rotatable on a shaft B 2 , which rotatably connects the arm section A 2  to the arms A 1 , and which in turn is fixed for rotation with a sun gear Sc meshing with a planet gear Pc rotatable about a fixed shaft 11c mounted on the arm A 2 . The planet gear Pc is fixed to rotate with an intermediate gear Mc which is coupled through gears 14c and 15c themselves interconnected by a shaft 12c with transmission gear Tc fixed to a shaft B 3 , which forms the pivotal interconnection between the arm sections A 2 , A 3 , and to the arm section A 3 . The ratio of the gears Tc, Mc, Pc and Sc is chosen such that (t 2  x t 4 )/(t 1  x t 3 ) = 2 where t 1  - t 4  are the number of teeth on the gears Tc, Mc, Pc, Sc in that order. such a ratio provides, with an input through drive gear C, which is coupled to a planet gear P 2 d fixed to the shaft B 2 , for the arm sections to move through equal but opposite angles to stretch the arm. An input through drive gear D causes arms A 1  and hence shaft B 2  to rotate about the shaft B 1  and the ratio of gears Sc, Sd, P 2 d and C are chosen such that (t 6  x t 7 )/(t 8  x t 4 ( = 1 where t 4  - t 8  are the number of teeth on the gears Sc, Sd, P 2 d and C. Such a ratio causes the arm sections A 2 , A 3  to pivot through equal angles in the same direction and thus to rotate as one about the axis B 2 . Further epicyclic gear trains Ef 1 , Ef 2 , Ef 3 , comprising a sun gear Sf 1 , Sf 2 , Sf 3  mounted on a shaft B 1 , B 2 , B 3 , a planet gear Pf 1 , Pf 2 , Pf 3  and an intermediate gear Mf 1 , Mf 2 , Mf 2  mounted on fixed shafts (11f), Fig. 4 (not shown), 1 1c, 11f 3  respectively and a transmission gear Tf 1 , Tf 2 , Tf 3  on the shafts B 2 , B 3 , B 4 , each has a ratio (t 1 <SP>1</SP> x t 3 <SP>1</SP>)/(t 2 <SP>1</SP> x t 4 <SP>1</SP>) = 1 wherein t 1 <SP>1</SP> - t 4 <SP>1</SP> correspond to the number of teeth on the transmission gear, the intermediate gear, the planet gear and the sun gear respectively of the gear trains Ef 1 , Ef 2 , Ef 3 . The transmission gear Tf 3  is fixed to rotate with the shaft B 4 , which is also fixed to the arm A 4 , and the gear ratios are such that with sun gear Sf 1 , fixed then the arm A 4  and hence the grasp A 5  will maintain their absolute angular orientation about shaft B 4  regardless of the disposition and movement of the arms A 2  A 3 . An input at sun gear Sf 1 , however, will result in an angular displacement of the arm A 4 . Similar gear trains Eh 1 , Eh 2 , Eh 3  are connected through gears 31h 4 , (36h 4 ), Fig. 6 (not shown), 34h 4 , 35h 4 , 37h 4 , 39h 4  and 40h 4  to the grasper A 5  to maintain the absolute angular orientation about the longitudinal axis of the arms regardless ofthe disposition and movement of the arms A 2 , A 3 . An input at sun gear Sh 1 , however, will result in a twisting of the grasper about the said longitudinal axis. Pulse motors (not shown) may be connected to the various inputs to provide for digital control of the robot.