What the robot protects against, and what not¶

Know what the hardware and the software catch, and what they do not, before you decide how the robot is guarded.

What is protected¶

Against	How	Where
A target outside the joint limits	The planner refuses it; a jog stops at the limit. Firmware 1, the commander and the Python API check the earlier, partly wider limits (Joint limits)	Commander, Python API
A speed or acceleration above the limits	Clamped to the robot model's limits	Commander, Python API
A move through a singularity (Cartesian)	The commander stops the move; the API's IK fails and refuses the command	Commander, Python API
A pose the arm cannot reach	The IK fails and the command is refused	Commander, Python API
Self-collision and collision with declared obstacles	Collision checking of planned moves and jogs against the robot's meshes and your keep-out shapes	Python API (set_shapes)
The E-stop pressed	Reported by the board, acted on by the PC software (Emergency stop)	Commander, Python API
A driver overheating	The TMC5160 shuts its outputs down when it gets too hot; the fan keeps it far below that. The joint then goes limp, and firmware 1 does not tell the PC	Control board
A short on a motor output	The TMC5160 switches the output off. Firmware 1 reads the driver's short and open-load flags once at start-up and does not report them	Control board

Not against	Why	What you do instead
A collision with something the software does not know	There are no joint encoders and no force sensing: the stepper pushes until it stalls, then loses steps silently	Keep the workspace clear; check programs in the simulator first; declare obstacles to the Python API's collision checker
Lost steps	Open-loop motors; the position is counted, not measured	After a stall or a collision, home again; keep speeds and payloads within the limits
A fall on power loss	No brakes	Switch off only in the parked pose; keep hands and objects out from under the arm
A frozen PC	The E-stop acts through the PC software; the firmware does not stop on its own	A mains switch on the power supply within reach
Lost communication with the PC	The firmware has no timeout: it keeps executing the last packet until the next one arrives. After a move to a position (programs, the Python API) the joint stops near that target. After a jog in the commander the joint keeps turning at the jog speed until it reaches its blocker	Keep the mains switch within reach; a short, direct USB cable
Motor temperature	Only the drivers are measured, not the motors	Reduce the current for long runs (Currents and temperatures)
The tool	The robot does not know what the tool does	Guard the tool as you would the robot
A wrong joint direction on a new build	The firmware trusts its configuration	Jog each joint briefly before homing

The commander's safety functions are described in Errors and recovery; the Python API's in Errors.