Page 522 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

• Shoulder azimuth
• Shoulder pitch
• Elbow pitch
• Wrist pitch
• Wrist yaw or forearm rotate
• Wrist rotate (may be continuous)
• Hand/gripper open/close
Examples of 4- and 7-function arms are shown in Figures 19.18 and 19.19.
FIGURE 19.18
Hydro-Lek 4-function manipulator.
19.3 Joint design 519
19.3 Joint design
Manipulators are composed of a variety of joints that are operated by linear or rotary actuators. Many wrist configurations include a gerotor actuator that allows continuous wrist rotation. Smaller electric vehicles may use an all-electric design for the grabber/manipulator actuators, but as the size and capability of the arms increase, they use hydraulic actuators that take advantage of their excellent lift-to-weight ratio characteristics.
In the case of the smaller electric vehicles, the number of functions and the range of motion of the manipulator may be very small because of the ability of the vehicle to “fly” the hand into posi- tion. As the arms grow in size and capability so does the number of functions. As a minimum, the following functions are necessary to position a larger arm:
• Shoulder azimuth
• Shoulder pitch
• Wrist or forearm rotate
• Hand/gripper open/close
The above functions allow the operator to position the manipulator to grasp in both a horizontal or vertical orientation. As the manipulators grow in complexity, additional joints are added that mimic the human arm, that is, shoulder, elbow, wrist, and hand. With this in mind, a basic 7-function manipulator will include the following:
(Courtesy Hydro-Lek.)