SPACE ROBOTICS

Robot is a system with a mechanical body, using computer as its brain. Integrating the sensors and actuators built into the mechanical body, the motions are realised with the computer software to execute the desired task. Robots are more flexible in terms of ability to perform new tasks or to carry out complex sequence of motion than other categories of automated manufacturing equipment. Today there is lot of interest in this field and a separate branch of technology ‘robotics’ has emerged. It is concerned with all problems of robot design, development and applications. The technology to substitute or subsidise the manned activities in space is called space robotics. Various applications of space robots are the inspection of a defective satellite, its repair, or the construction of a space station and supply goods to this station and its retrieval etc.   With the over lap of knowledge of kinematics, dynamics and control and progress in fundamental technologies it is about to become possible to design and develop the advanced robotics systems. And this will throw open the doors to explore and experience the universe and bring countless changes for the better in the ways we live.

DESCRIPTION OF STRUCTURE OF SPACE ROBOT

The proposed robot is of articulated type with 6 degrees of freedom (DOF). The reason for 6 DOF system rather than one with lesser number of DOF is that it is not possible to freeze all the information about possible operations of the payload/racks in 3D space to exclude some DOF of the robot. Hence, a versatile robot is preferred, as this will not impose any constraints on the design of the laboratory payload/racks and provide flexibility in the operation of the robot. A system with more than six DOF can be provided redundancies and can be used to overcome obstacles. However, the complexities in analysis and control for this configuration become multifold.

The robot consists of two arms i.e. an upper arm and a lower arm. The upper arm is fixed to the base and has rotational DOF about pitch and yaw axis. The lower arm is connected to the upper arm by a rotary joint about the pitch axis. These 3 DOF enable positioning of the end effector at any required point in the work space. A three-roll wrist mechanism at the end of the lower arm is used to orient the end effector about any axis. An end effector connected to the wrist performs the required functions of the hand. Motors through a drive circuit drive the joint of the arm and wrist. Angular encoders at each joint control the motion about each axis. The end effector is driven by a motor and a pressure sensor/strain gauges on the fingers are used to control the grasping force on the job.

SPACE ROBOT TELEOPERATION

Space robotics is one of the important technologies in space developments. Especially, it is highly desired to develop a completely autonomous robot, which can work without any aid of the astronauts. However, with the present state of technologies, it is not possible to develop a complete autonomous space robot. Therefore, the teleoperation technologies for the robots with high levels of autonomy become very important. Currently, the technologies where an operator teleoperates a space robot from within a spacecraft are already in practical use, like the capture of a satellite with the shuttle arm. However, the number of astronauts in space is limited, and it is not possible to achieve rapid progresses in space developments with the teleoperation from within the spacecraft. For this reason, it has become highly desired to develop the technologies for the teleoperation of space robots from the ground in the future space missions.

CONCLUSION

In the future, robotics will make it possible for billions of people to have lives of leisure instead of the current preoccupation with material needs. There are hundreds of millions who are now fascinated by space but do not have the means to explore it. For them space robotics will throw open the door to explore and experience the universe.