Robotics deep dive: FLUIDIC TENDONS There are three ways to move a robot finger, and a startup just added the third. Cable tendons pull the joint from afar. Direct drive puts a geared motor in the finger. Tacta @TactaSystems pushes the joint with sealed fluid. Here is the idea, and it is closer to a backhoe than to a hand. A simple motor in the torso drives a piston. The piston pushes a tiny sealed volume of oil down a thin tube. At the far end the oil pushes another piston that moves the finger joint. Two lines per joint, one to push and one to pull, so it is quick in both directions. Nothing electric reaches the hand. No motor, no heat, no wires. The power lives in the torso and the fingers stay cold and thin. Tacta calls this a fluidic tendon, and it is not hydraulics. Hydraulics runs a reservoir and a bank of valves at high pressure, and it leaks. This is a closed, sealed, low-volume oil line, monitored for temperature and pressure, closer to hydrostatics. Why go to all this trouble? One word: robustness. Cable tendons stretch and fray, and most cable hands are lucky to pass a million cycles. If one cable breaks the whole hand is done. Tacta publishes 30 million cycles per joint, and a failed finger pulls off and swaps in minutes, with no downtime on the line. The hand is human-sized, 15 joints, three per finger, and each fingertip lifts about 2 kg at up to 400 degrees per second. Tacta came out of stealth in July, builds the hands in Palo Alto, ships them on an off-the-shelf cobot arm, and targets high-value factory work from early 2027.