has been described according to the invention the construction of the arm and articulates can be very much simplified because the angular positions of all articulates can be controlled by means of a single drive shaft unit fig1 shows another embodiment having a construction of the arm modules 2a to 2f different from the construction of those shown in fig3 namely this embodiment employs a motor 7b and an encoder 8b in place of the clutch 23b brake 24b drive shaft 14b bevel gears 15b 16b 17b and other related elements while the control line 114b leading from the address decoder 40b is substituted by lines 131b 132b furthermore an additional buffer 96b is used and a driver 97b is provided in place of the articulate control circuit 41b in this embodimnet two address bit patterns concerning the motor 7b and the encoder 8b are used as the code peculiar to the address code 97b the address bit patterns are determined for example as shown in table 2 below table 2______________________________________module address address bitnumber decoder device pattern______________________________________arm module 2a 40a motor 0001 encoder 1001arm module 2b 40b motor 0010 encoder 1010arm module 2c 40c motor 0011 encoder 1011arm module 2d 40d motor 0100 encoder 1100arm module 2e 40e motor 0101 encoder 1101arm module 2f 40f motor 0110 encoder 1110gripper 3 40g motor 0111 encoder 1111no appointed 0000articulate 1000______________________________________ the motor 7b includes a reduction gear not shown fixed to the arm portion 11b the output shaft of the motor 7b is connected to the articulate shaft.