In a jet loom in which a weft, released from weft retaining action exerted by weft release control means operable between a state in which said weft is allowed to be withdrawn from a weft storing means and a state in which said weft is prevented from being withdrawn from said weft storing means, is inserted in a given direction into a warp shed under action of an air jet injected by a main inserting nozzle, apparatus for controlling the insertion of the weft comprising:
- weft insertion start timing detecting means including a weft release detector disposed in association with said weft release control means for detecting releasing of the weft from the state retained by said weft release control means for detecting the timing at which insertion of the weft commences;
- weft leading end arrival timing detecting means including a weft detector disposed at a predetermined weft insertion terminal position for detecting the timing at which the leading end of the weft arrives at said terminal position;
- input means for inputting:
- a first group of sequential arrayed data resulting from orderly classification of data for weft insertion start timing and weft leading end arrival timing in accordance with a sequencing rule;
- and a second group of sequential control elements resulting from classification of control elements relating to control quantities for at least weft release timing at which the weft is released from the weft retaining action exerted by said weft release means, and air jet ejection timing at which said air jet is injected by said main inserting nozzle, both of said timing affecting said weft insertion timing and said weft leading end timing, respectively;
- control quantity determining means including a control computer for (a) determining specific data for said weft insertion start timing and said leading end arrival timing in said first group of sequential arrayed data as well as likelihood values of said data on the basis of values determined experimentally for said weft insertion start timing and said weft leading end arrival timing, (b) selecting from said second group those of said control elements which bear specific correspondence relations to said determined specific data, and (c) determining control quantities for said weft release timing and said air jet injection timing on the basis of said selected control elements and said determined likelihood value;
- and
- a plurality of auxiliary weft inserting nozzles disposed downstream of said main inserting nozzle in the direction in which said weft is inserted, a weft propulsion nozzle disposed upstream of said main inserting nozzle in alignment therewith;
- said predetermined weft insertion terminal position being located downstream of said auxiliary weft inserting nozzles,
- said control computer, on the basis of the weft insertion start timing detected by said weft release detector and the weft leading end arrival timing detected by said weft detector, controls:
- the weft release timing of said weft release control means, the air jet injection timing of said main inserting nozzle, the air injection timing (.theta..sub.31) of said propulsion nozzle and the air injection stop timing of said auxiliary weft inserting nozzles, and
- said control computer comprises:
- (a) sampling means for sampling a predetermined number of times a weft insertion start timing signal obtained from said weft release detector and said weft leading end arrival timing signal obtained from said weft detector, and
- (b) calculating means for calculating mean values (x, y) of said sampled weft insertion start timing and said weft leading end arrival timing, respectively, for every predetermined number of samplings, and determining the set of relevant weft insertion start timing data (G.sub.m) to which said calculated weft insertion start timing value (x) belongs and the set of relevant weft leading end arrival timing data (H.sub.n) to which said calculated weft leading end arrival time value (y) belongs, wherein likelihood ratios {g.sub.m (x), g.sub.m+1 (x), h.sub.n (y), h.sub.n+1 (y)} are arithmetically determined in accordance with functions (g.sub.m, g.sub.m+1) corresponding to said relevant weft insertion start timing data (G.sub.m, G.sub.m+1) and functions (h.sub.n, h.sub.n+1) corresponding to said relevant weft leading end arrival timing data (H.sub.n, H.sub.n+1).