What you can learn with the Cartesian robot
What a Cartesian robot is
It has three perpendicular linear axes, X, Y and Z, mounted on a gantry. Its kinematics are direct: the tool position is simply the axis positions. That makes it accurate, easy to program and scalable to work areas of several metres. It is used for palletizing, dispensing, cutting, 3D printing and machine tending.
Belt or ball screw
X and Y use toothed belts: a pulley moving 100 mm per revolution allows 1500 mm/s with the motor at 900 rpm. Z uses a ball screw with a 10 mm lead: slower, but stiffer and fitted with a brake, because it is the axis that holds the weight when power is cut. Each motor’s rpm reading is the speed divided by the travel per revolution.
Homing and limit switches
An incremental encoder only counts pulses: at power-up it doesn’t know where the axis is. The homing routine looks for a sensor at medium speed, backs off and touches it again slowly to repeat the position accurately. Then the software limits are enabled. The physical limit switches remain as the last line of protection.
Trapezoidal profile
No axis jumps from 0 to the programmed speed instantly: it accelerates, cruises at constant speed and brakes. If the move is short it never reaches full speed and the profile becomes triangular. You can see each ramp in the Process chart. In G64 mode the control looks ahead to the next block and doesn’t brake if the path stays tangent.
Suction cups and acceleration
A suction cup holds with F = Δp · A · η. With Ø50 mm, −0.6 bar and η = 0.7 on cardboard, that is about 82 N. The box needs m · (g + a/μ) when the axis accelerates horizontally, because friction is what drags it along. With 12 kg and full acceleration, two cups are not enough: you need four, or less acceleration. A safety factor of 1.5 is recommended.
Palletizing without collisions
The program rises to a safe height before every transfer, descends slowly over the last few millimetres and waits for the vacuum to build before lifting. If the box being carried brushes one already placed, the control detects the collision and stops the machine. Release the box from too high and it falls and ends up badly stacked.
Adhesive dispensing
The bead diameter comes from the volume per millimetre: d = √(4Q / πv). If the axis brakes at a corner while the valve keeps the same flow, a blob forms. Real-world fixes are to round the corners and work in continuous mode, or to synchronize the flow with the speed through an analog output.
Cell safety
The fence with an interlocked door prevents entry while the machine is in automatic. Opening the door triggers a controlled stop (category 1): the axes brake along the path and then torque is removed. The emergency stop brakes much harder. If you are carrying a heavy box, it can come off the suction cups, another reason not to overload them.
Other robots in the lab: KUKA arm · SCARA · Delta · Cobot · Kinematics. More simulators in Labs. Educational simulator: the figures are representative and do not replace the manufacturer’s documentation or the risk assessment of a real installation.