19-04-2014, 03:31 PM
FORWARD-REVERSE KINEMATIC WALKER POWERED WITH ELECTRIC MOTOR
INTRODUCTION
A walker is a vehicle that moves on legs rather than wheel or track. The kinematic walker is six-legged machine that can walk on any surface. It is an arrangement of six linkages that are powered together by a single motor. This device is analogous to a six-legged insect such as a spider. The motor can either be powered by mains or a battery. The kinematic walker comprises six legs that move simultaneously to provide motion. Each of these six linkages are made of a four bar mechanism.
Vehicles which operate more or less autonomously are considered as belonging to the robot’s family. The legged vehicles have the potential advantage to be able to operate over irregular terrain. Walking robots (WR), in comparison with industrial robots which are dextrous arms (6 or more D.O.F.) able to ensure the precise positioning of the end-effector, comprise a body and legs, each kinematic chains with no more than 3 D.O.F. which support the body and ensure the gait, the locomotion mechanism. Terrain adaptive walkers have the ability to individually place their feet at desired position on the terrain The legs can be in supporting state when the legs are in contact with the ground, and the body is moving or not, with respect to the footholds, or in stepping or transfer state when the leg is detached and has a relative movement to the robot’s body.
Brief Explanation And Working:
It has electric motor which is the power house for mechanism. The power from motor is transmitted to the crankshaft with chain links gives motion to the legs. Due to this the whole mechanism moves forward.
The six legs of kinematic walker move synchronously with several angular intervals in between them so that they give a walking motion just like a six-legged insect. Four fixed links surround the linkages and support their movement. Actually eight of these fixed links are needed with each of the linkage having two of these on either side. As these fixed links, extend over to the other side of the common rod they are counted as four. Each of these linkage functions as a leg by giving a reciprocating motion.
Each of the six linkages are assembled by connecting the 4 links together by bolts so as to form the 4 bar linkage as desired. Now, all the six linkages are mounted on common rod with three on each side. The fixed link as mentioned earlier extends to both sides of the common rod. There are four such links which sandwich the linkages in between them. These links support the 4 bar linkages. For our requirement we need one link to rotate which is the rotating link is connected to the shaft of a motor and this link is given the power. The legs reciprocate and give the motion like a real insect leg. The fixed link remains stationery. The other connecting link which is mounted over the common rod is the largest link and it also reciprocates like the legs:
1. Each of the two sets consisting of three 4 bar linkages on either side of the common rod must be powered in the same direction for the whole machine to move in one direction. Thus the power from a single motor is divided by sprockets and a chain.
2. When the motor is given the electrical input from the mains it runs the sprocket connected to its shaft. The sprocket in turn moves the chain meshed to it. Thus the chain transmits power to both the sprockets.