Chapter 1: Introduction Inner Arms Three robot motors attach directly to the inner arms through high-performance gear reducers. If the robot has a theta rotation motor, it is mounted at the top of the robot base. The following figure shows an inner arm from a Hornet 565. RIA-compliant hard stops limit the inner arm motion to -53° and +114.6°. Ball Joints, Outer Arms The inner arm motion is transmitted to the platform through the outer arms, which are con- nected between the inner arms and platform with precision ball joints. The outer arms are car- bon fiber epoxied assemblies with identical ball joint sockets at each end.
A bearing insert in each socket accepts the ball joint studs on the inner arms and platform, and allows for approx- imately ± 60° of relative motion. No ball joint lubrication is required. Inner Arm Ball Joint Stud Ball Joint Socket Insert Pressed Pin Ball Joint Socket Outer Arm Springs Spring Horseshoe Outer Arms Figure 1-3. Ball Joint Assembly Each pair of outer arms is held together with spring assemblies that pre-tension the ball joints. The outer arms can be installed and removed without tools. Platforms The platform converts the motion of the Hornet 565 motors into Cartesian motion, and, for the four-motor version, theta rotation of the robot tool flange.
The fixed platform, with no theta rotation, is stainless steel. The J4 platform has a fourth motor, theta drive shaft, and geared J4 platform that can rotate its tool flange ±360°. The platform is electroless-nickel-plated aluminum. Both platforms have a 38 mm hole through their center, for users to route air lines or electric cables to the tool flange. For the J4 version of the Hornet 565, a stainless steel theta drive shaft attaches to a U-joint at both the platform and the J4 motor on the robot. Hornet 565 Robot User's Guide, 14608-000 Rev C Page 11 of 156