Shoulder joint and brake for a robotic arm

An upper body support system comprising:

• a harness assembly couplable to a torso of a human user;
• a plurality of upper body support assemblies each coupled to the harness assembly, wherein a first of the plurality of upper body support assemblies is coupled to the harness assembly on a first side of the torso of the human user, and wherein a second of the plurality of upper body support assemblies is coupled to the harness assembly on a second side of the torso of the human user opposite the first side, wherein each of the plurality of upper body support assemblies includes:
• a mechanical shoulder joint and brake device, comprising:
• a shoulder joint frame;
• a first mechanical shaft structure constrained to rotate with respect to the shoulder joint frame about a first shoulder joint axis;
• a first brake stack including:
• a first plurality of brake plates fixedly coupled to the first mechanical shaft structure;
• a second plurality of brake plates interleaved with the first plurality of brake plates, the second plurality of brake plates constrained to translate with respect to the shoulder joint frame along a first braking axis;
• a first lever structure constrained to rotate with respect to the shoulder joint frame about a first clamping axis, the first clamping axis orthogonal to the first braking axis, the first lever structure in mechanical contact with the first braking stack at a first distance from the first clamping axis;
• and
• a first brake force actuator attached to the shoulder joint frame, the first brake force actuator in mechanical contact with the first lever structure at a second distance from the first clamping axis, wherein the second distance is greater than the first distance.

A system, comprising:

• a frame;
• a first shaft constrained to rotate with respect to the frame about a first axis;
• a first brake stack including:
• a first plurality of brake plates fixedly coupled to the first shaft;
• a second plurality of brake plates interleaved with the first plurality of brake plates, the second plurality of brake plates constrained to translate with respect to the frame along a first braking axis;
• a first lever constrained to rotate with respect to the frame about a first clamping axis, the first lever in mechanical contact with the first braking stack at a first distance from the first clamping axis;
• and
• a first brake force actuator attached to the frame, the first brake force actuator in mechanical contact with the first lever structure at a second distance from the first clamping axis, wherein the second distance is greater than the first distances;
• a second shaft constrained to rotate with respect to the frame about a second axis;
• a second brake stack including:
• a third plurality of brake plates fixedly coupled to the second shaft;
• a fourth plurality of brake plates interleaved with the third plurality of brake plates, the fourth plurality of brake plates constrained to translate with respect to the frame along a second braking axis;
• a second lever constrained to rotate with respect to the frame about a second clamping axis, the second clamping axis orthogonal to the second braking axis, the second lever in mechanical contact with the second braking stack at a third distance from the second clamping axis;
• a second brake force actuator attached to the frame, the second brake force actuator in mechanical contact with the second lever at a fourth distance from the second clamping axis, wherein the fourth distance is greater than the third distance.