The control frame is where most of the hardware which controls the sequence of operations is mounted. It is the bottom-most section of the structure. There is one control frame for each control segment of the device.
The picture shows the conrtol frame, viewed from above.
Next to each blue/purple composite connector are shown the connectors which are put together to form it, in their approximate orientations in the structure.
The missing connectors are provided by the bit frame which will be attatched immediately above the control frame.
Each of the blue/purple connectors at the bottom level of the control frame stands on a white strut. These white strut legs are not shown in the picture.