Collaborative Robotics

robot and frank is where it is supposedly safe for a person to work with and in close proximity to a robot arm. This however is illusionary. A robot that is tuned to stop on impact may not be safe. For a start, any mass in motion needs time to stop; it's a law of physics (Newton's first law). Robots where the trip torque can be set at low thresholds are too slow for any practical industrial application. Where you see a video of a robot bumping into a person, then stopping, the collision is always in open air. If the same robot traps your hand between its end effector and the bench it will hurt you. Any robot carrying an end effector or payload of any mass at any practical speed is a hazard and it will hurt you no matter what label you put on it.

Please view this Youtube video on the reality of getting in the way of a so-called collaborative robot.
As you can see stopping a robot on impact is too late. The best system is where the work area has proximity detectors so the robot stops before impact (see below).
This article provides an excellent overview of the subject.

What do ST robots do? Like any robot, the energy, the shape of the end effector or any hazardous payload could hurt or cause injury and no robot is immune. In a collision, an ST robot will stall and the motors will come out of synchronism and impart no further torque. Each move is checked with encoders which detect a stall and an error is displayed. No further motion can take place.
The smaller R12 robot may not cause any harm depending on circumstances but a risk assessment should still be carried out and precautions taken.

ST Robotics Workspace Sentry: collaborative robotics safety system

sentry ST has a robot and area safety system based on sensors that can be strategically positioned around the shared workspace. When the user gets within a set distance the robot stops with enhanced deceleration. This is considerably safer than a robot that simply stops on contact. However, a risk assessment should always be carried out.