The software and hardware products produced in the MIT Field and Space Robotics Laboratory include:
Flexarm [53, 54]:
With this software package, static and dynamic simulations are performed for mechanical systems with rigid and flexible members, taking into account non-linear characteristic such as clearance in the joints.
Ribs and MSV [18, 19]:
With these software packages, dynamic simulations are performed for free-floating and compliant based manipulator systems using a recursive Newton-Euler method. Graphical animations of system computer models are performed that help design and plan the actions of future space robotic systems.
VES I [55, 56]:
This is the first prototype of a system that can emulate the motion of free floating, free flying or flexible based space manipulator system. It consists of a six-degree of freedom hydraulically driven platform. A six-degree of freedom force sensor and a PUMA 250 manipulator were placed on the top of the platform.
VES II [57-59]:
The VES II, is the second generation of vehicle emulation systems. As VES I, it consists of a six DOF Stewart platform (see Figure 1), hydraulically driven, that can emulate the dynamic behavior of a wide class of space robotic systems. This time, the system workspace is very large so that the vehicle motion that is emulated is close to realistic ranges of motion. On the platform a Puma 560 is mounted. When the manipulator is performing a task, interaction forces are transmitted to its base. These forces and moments are sensed with a force sensor. Under this excitation, a computer model of the space robotic system, yields the displacement of the system which is reproduced on real time by the platform. A second prototype of this second generation system is found in NASA Langley Research System.
Shaky I :
A planar experimental flexible base manipulator system, called Shaky I, has been built to test path-planning and control methods for long reach flexible base manipulator systems. This system consists of a two link, two degree of freedom, planar manipulator mounted on a flexible structure (see Figure 2.) Strain gauges on the structure were used to sense the displacement of the flexible base.
Shaky II :
A more general testbed has been built to study the behavior of long reach manipulators. This system, called Shaky II, consists of a large vertical flexible beam that can exhibit spatial vibrations and a small PUMA 250 manipulator (see figure 3.) The dynamic characteristics of the beam have been changed, by making holes on its structure, trying to obtain frequencies and flexibilities found in real LRMS. Strain gauges on the structure infer the supporting structure passive motion.
This is a planar laboratory climbing system (see Figure 4.) It consists of a main body with three limbs (legs), each with two links and two actuated joints. The actuated joints are driven by electric motors with a 792:1 gear ratio transmission. The on-board sensors consist of encoders measuring the joint angles and a pendulum-based inclinometer used to measure the angle of the center body. A force sensor was mounted on a ladder step to measure the horizontal force applied by the free foot.
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