Movement transmission device, in particular a robot arm

A movement transmission method, in which a movement transmission device is used for transmitting the movement, the movement transmission device comprising:

• a first shaft rotatably mounted about its longitudinal axis,
• a wheel rotatably mounted about its central axis and on which at least one succession of notches is disposed circumferentially,
• at least three arms for transmitting together movement between the first shaft and the wheel,
• wherein:
• each arm is provided with a plurality of teeth for cooperating with the notches of the wheel, the plurality of teeth being arranged on a circular portion so as to form a ring gear portion,
• each arm is articulated on a first bearing eccentric to a first axis about which the bearing is rotatably mounted, the first bearing and the first shaft being linked to rotate in synchronism;
• the wheel and each arm are guided mechanically so that:
• the arm describes a cyclic movement for each revolution of the first bearing on which it is articulated, and
• the arm is in engagement with the wheel for at least a part of the cyclic movement through cooperation of the teeth of the arm with notches of the wheel so that displacement of the one causes the displacement of the other,
• the first bearings are arranged so that there is at least one arm engaged with the wheel whatever the angle of rotation of the first shaft,
• each arm is also articulated on a second bearing eccentric to a second axis about which the second bearing is rotatably mounted to maintain the arm parallel to itself regardless of the angle of rotation of the first shaft, and
• the first bearings are arranged on the first shaft and the second bearings are arranged on a same second shaft,
• wherein the method comprises using only one of the first and second shafts of the movement transmission device as a drive shaft, the other of the first and second shafts being used as a secondary shaft to which the arms transmit a rotation movement of the drive shaft.

A movement transmission method, in which a movement transmission device is used for transmitting the movement, the movement transmission device comprising:

• a first shaft rotatably mounted about its longitudinal axis,
• a wheel rotatably mounted about its central axis and on which at least one succession of notches is disposed circumferentially,
• at least three arms for transmitting together movement between the first shaft and the wheel,
• wherein:
• each arm comprises a ring gear inside which teeth are distributed over its entire circumference for cooperation with the notches of the wheel,
• each arm is articulated on a first bearing eccentric to a first axis about which the bearing is rotatably mounted, the first bearing and the first shaft being linked to rotate in synchronism;
• the wheel and each arm are guided mechanically so that:
• the arm describes a cyclic movement for each revolution of the first bearing on which it is articulated, and
• the arm is in engagement with the wheel during the cyclic movement through cooperation of the teeth of the arm with notches of the wheel so that displacement of the one causes the displacement of the other, each tooth being successively engaged in and then disengaged from a notch of the movable member during the cyclic movement of the arm,
• each arm is also articulated on a second bearing eccentric to a second axis about which the second bearing is rotatably mounted to maintain the arm parallel to itself regardless of the angle of rotation of the first shaft, and
• the first bearings are arranged on the first shaft and the second bearings are arranged on a same second shaft,
• wherein the method comprises using only one of the first and second shafts of the movement transmission device as a drive shaft, the other of the first and second shafts being used as a secondary shaft to which the arms transmit a rotation movement of the drive shaft.