Gear packaging for robot arms

A robot arm as claimed in any preceding claim, wherein the arm comprises:

• a third limb adjacent the first limb and on the opposite side of the first limb to the coupler;
• a fourth limb adjacent the second limb and on the opposite side of the second limb to the coupler;
• a third revolute joint whereby the third limb and the first limb are attached together, the third revolute joint having a third rotation axis orthogonal to the first rotation axis;
• and
• a fourth revolute joint whereby the fourth limb and the second limb are attached together, the fourth revolute joint having a fourth rotation axis orthogonal to the second rotation axis.

A torque sensor arrangement configured to attach between a first part and a second part to sense torque therebetween, the torque sensor arrangement comprising:

• an interface member having on its exterior an engagement configuration configured to rotationally engage the first part;
• a torsion member comprising a deflectable body attached at one end thereof to the interface member and comprising, at the other end of the deflectable body, an engagement configuration configured to rotationally engage the second part;
• and
• a deflection sensor attached to the deflectable body;
• wherein the interface member defines a rigid sleeve extending around the deflectable body and the torque sensor arrangement further comprises a bushing located between and in contact with both the sleeve and the deflectable body.

A robot arm having a first limb and a second limb connected by a revolute joint, comprising a rotary position sensor arrangement for sensing rotary motion about a first rotation axis between a first part and a second part, the arrangement comprising:

• a first ring defining a plurality of magnetic poles, the first ring being attached to the first part;
• a second ring defining a plurality of magnetic poles, the second ring being attached to the first part;
• a first sensor attached to the second part for sensing motion of the magnetic poles of the first ring past that sensor;
• and
• a second sensor attached to the second part for sensing motion of the magnetic poles of the second ring past that sensor;
• the first ring and the second ring being spaced apart along the rotation axis and on opposite sides of the revolute joint.