Calibration and Defining Movement
In order to define a movement in space, the movement needs to be measured. Measurements require a starting point or zero point, called a calibration point. It is important for robots to be calibrated so they can use a standard point to measure their movements. Moving to a calibration point is called calibration.
Let’s say a foreman wants to write a set of instructions with measurements for an employee to draw a circle on the white board in the exact place that they have just drawn one. If the instruction’s measurements do not include a specific starting point, there is almost no chance the circle will be drawn in the same location. This starting point would be known as the calibration point for the drawing.
When robots are moving, their axes define their motion. The workspace they sweep through is known as the robot’s work-volume or work envelope. With the arm mounted on the VEX V5 Workcell, its work-volume or work envelope includes all the space it can move through, in all directions.
A robot’s work-volume is not only defined by the robot’s axes, but the structure of the robot can also define its motion. For instance, a robot’s wrist might be able to make a full rotation, but its arm might block a tool on the wrist from making a full turn. An area in which the robot can not move is called a singularity.
For example, the arm mounted on the V5 Workcell can pivot up and down at the shoulder. However, there is a post which holds the shoulder bracket together which limits the arm’s height. The area above the limit of the arm would be considered a singularity.