What is the purpose of setting an over-travel margin beyond the software limits?

• A. To provide a safety buffer
• B. To increase speed
• C. To reduce accuracy
• D. To save energy

Answer: (A)

Setting an over-travel margin creates a safety buffer around the defined travel limits. This buffer accounts for real-world factors that can push the system slightly beyond its ideal path, such as inertia during rapid moves, encoder or sensor inaccuracy, mechanical backlash, and thermal expansion.

With soft limits or software-defined boundaries, the controller can begin a controlled deceleration and stop before the physical end stops are reached. The margin gives the system time and space to slow down safely, preventing collisions or damage to axes, drives, tools, or fixtures. It also reduces the chance of nuisance alarms or unexpected stops due to tiny position errors.

In short, the purpose is to enhance safety and reliability by ensuring the machine stops gracefully before hitting the hard limit, not to increase speed, reduce accuracy, or save energy.