A little history

Unimate, 1961

The first industrial arm was the Unimate. The inventor George Devol patented “programmed article transfer”, and the engineer Joseph Engelberger turned the patent into a machine. In 1961 the first arm went to work at a General Motors plant: it took hot castings out of a die-casting machine and stacked them aside — heavy work and dangerous for people. The arm kept its steps on a magnetic drum: which joint to turn where on each step. Our machine does the same — only a CD4017 steps the steps, and the angles are in the pose memory.

The first industrial arm, the Unimate, at a General Motors plant: it took hot castings out of the die-casting machine and stacked them. The steps were on a magnetic drum.

A PLC instead of a relay cabinet, 1968

Machines were then run by cabinets of relays: each rule was its own wire. Changing the order of work meant rewiring the cabinet. In 1968 General Motors asked for a “programmable controller”, and the engineer Dick Morley and his colleagues built the Modicon 084: the rules became a record in memory, and the wires stayed the same. That is how PLCs came about — they still run conveyors today. Lessons 5 and 6 follow this path: first a brain of chips and wires, then the same brain as the firmware of one GAL.

From a relay cabinet to a PLC: in the cabinet each rule is its own wire, in a programmable controller the rules are a record in memory. Lessons 5 and 6 go the same way: chips and wires → the firmware of one GAL.

SCARA, 1978

Professor Hiroshi Makino of Yamanashi University in Japan came up with an arm for assembly: two joints that turn only in the horizontal plane, like a shoulder and an elbow lying on a table. Such an arm is fast and precise sideways and “soft” in height — it was named SCARA: Selective Compliance Assembly Robot Arm — stiff where precision is needed and yielding where a part has to be pressed into place. The name stuck and became a common noun: today any arm with two horizontal joints is called a SCARA, whoever makes it. Such arms sort parts, put chips onto boards and pack pills. Our arm is a SCARA too: a shoulder, a beam, an elbow, a beam, a gripper.

SCARA (Selective Compliance Assembly Robot Arm) — an arm for assembly: the shoulder and the elbow turn only in the horizontal plane, one axis moves in height. Our arm is a SCARA without the height axis.

Servos from model planes

Servos like the ones in the kit came from radio-controlled models: one wire, a pulse every 20 ms, the pulse length is the angle. A model plane moves its rudders, a toy robot its legs, and in our kit the shoulder and the elbow turn this way. A counter, a compare and a clock — the same scheme as in the first proportional radio sets: there, too, the pulse length was measured out step by step.