Tracer control system

A tracer control system for starting deceleration control before a jerk point in the surface configuration of a model a predetermined surface portion of which is to be traced along a trace path, said system comprising a stylus attached to a tracer head, said tracer head providing displacement signals corresponding to the displacement of said stylus with respect to said tracer head, and said system including means for calculating a composite displacement signal and direction-of-displacement signals from said displacement signals, said trace path being constituted of plural sequential tracings of said tracer head for scanning the portion of said model to be traced, each said sequential tracing having a correspondence to the prior sequential tracing, for providing said scanning in a predetermined mode over said portion of said model, said system comprising;

• detecting means for detecting each jerk point in each sequential tracing, said detecting being based on said displacement signals;
• a memory for storing a predetermined portion of the positional information of each said detected jerk point until at least during the next one of said sequential tracings in the trace path;
• speed reduction means for reduction of the trace velocity at a predetermined interval before the respective positional information of each jerk point stored in the memory as a result of having been detected at least during the prior sequential tracing;
• updating means, when a jerk point is detected in a sequential tracing that corresponds to a jerk point whose positional information was stored in the prior tracing, for updating the memory by replacing the previously stored positional information with the respective newly detected positional information;
• and
• means for subsequently releasing the reduction of the trace velocity after said detection of each said jerk point.