Benchtop robots – a brief description
With a footprint not much larger than a piece of A4 paper and a working area of 200 x 200mm, the smallest
machines still have all the functionality of their larger brethren. Bigger versions cover 800 x 600mm with a Z-axis of 200mm. They are often self-contained, controlled by internal computers.
Typically, programming is by means of a teach pendant, using simple step-by-step instructions. Program inputs
are prompted. Programs are stored on the machine or, optionally, can be kept off the machine on a PC. Software
can be generic, allowing full control of all functionality by the programmer, or function specific (e.g.
dispensing), where the software is customised and even more user-friendly. Point-to-point and continuous path
motion are selectable. Whilst 2-axis machines are available, 3-axis are the most popular, with full interpolation
of lines, arcs and circles through all three axes. A fourth, rotational axis is used for more complex, non-planar
jobs. Positional accuracy is within fractions of millimetres (0.01mm is typical), and movement speeds can reach
one meter per second. There are inputs and outputs which allow an interface with external devices (e.g. pick and
place pneumatics). They may be driven by servo or stepper motors, with belt or ball screw drives.