Overview
Most assembly operations in aircraft manufacturing are currently
done manually. Although aircraft are small in lot size,
numerous repetitive assembly operations have to be performed
on a single aircraft. The conditions are often ergonomically
challenging and these result in low productivity as well as
frequent injuries. Thus, there is a need to shift from manual
assembly to automated robotic assembly. The following wingbox
assembly illustrates this.
Fig. 1 shows a mock-up of the cross-section of an aircraft
wing-box. Several assembly operations, such as burr-less
drilling and fastener installations, have to be carried out inside
the wing-box after the upper and lower skin panels are in
place. The interior of the wing-box is accessible only through
small portholes along its length. The portholes are roughly
rectangular with dimensions of 45 cm by 23 cm. The wingbox
also has a substantial span, which varies from 1 m to 3
m depending upon the size of the aircraft. The height of the
wing-box varies from about 20 cm to 90 cm, depending upon
the size of the aircraft. Presently, the assembly operations are
carried out manually. A worker enters the wing-box through
the small portholes and lies flat on the base, while carrying
out the assembly operations. Evidently, the working conditions
are ergonomically challenging.
Current Members
Professor H. Harry Asada, Ph.D., Ford Professor of Mechanical Engineering, MIT
Binayak Roy, Ph.D. Candidate in Mechanical Engineering, MIT
A Gravity-assisted Underactuated Snake Robot for Aircraft Manufacturing
Manas Menon, Ph.D. Candidate in Mechanical Engineering, MIT
Spider Robots for Aircraft Manufacturing
Current Projects
Underactuated Snake Robot
We have proposed a “Nested-Channel” serial linkage mechanism capable of operating inside an aircraft wing box . The links are essentially C-channels with successively smaller base and leg lengths, as shown in Fig. 2. They are connected by 1 d.o.f rotary joints, the axes of which are parallel. The use of channel structures is advantageous for a number of reasons. The channels can fold into each other resulting in an extremely compact structure during entry through the porthole, as shown in Fig. 2. Once inside the wing-box, the links may be deployed to access distal points in the assembly space
The lack of a compact, powerful and high stroke actuation
mechanism is the primary bottleneck in the development of the
hyper articulated arm. In our previous work, we have proposed
an underactuated design concept, which obviates the use of
dedicated actuators for each joint. Instead, we utilize gravity
for driving individual joints. This drastically reduces the size
and weight of the manipulator arm. The methodology requires
a single actuator for tilting the arm at the base. This single
actuator can be placed outside the wing-box and can be used
in conjunction with simple locking mechanisms to reconfigure
the serial linkage structure.
Related Publications
B. Roy, H.H. Asada, “Closed Loop Control of a Gravity-assisted
Underactuated Snake Robot with Application to
Aircraft Wing-Box Assembly,” in Robotics Science and Systems, 2007.