The downward spiral has been precipitous for Neil Blomkamp, the South African filmmaker who began his feature career with the estimable “District 9,” suffered a sophomore slump with the ambitious failure “Elysium,” and now scrapes the bottom of the barrel with this dumb, ugly piece of sub-comic book sci-fi tripe cobbled together from scraps of other, better pictures. Change the second letter of its title and you’ll have a pretty good description of “Chappie.”

The picture is about artificial intelligence, but exhibits none of the natural sort. Stealing its premise from “Robocop,” it’s about a squadron of android police who have brought order to violence-prone Johannesburg in 2016 and big profits to Tetravaal, the weapons company run by Michelle Bradley (Sigourney Weaver) that manufactures them. The Scouts, as they’re called, differ from the Robocops in that they have no human component, just electronic components.

That disturbs one of Tetravaal’s engineers, Vincent Moore (Hugh Jackman), whose alternate system, the much larger Moose operated via a neural helmet by a real person, has been sidelined by the success of Scout. Still, the current level of achievement is not enough for Scout’s creator Deon (Dev Patel), who wants to perfect his bot by making it capable of feeling, thinking and learning—something that Bradley dismisses as a project unsuitable for a weapons company. So Deon decides to proceed on his own, using a mangled Scout as his guinea pig. Unfortunately, his prototype, which comes to be called Chappie (voiced by Sharlto Copley), falls into the hands of a trio of criminals—Ninja and Yolandi (played by Watkin Tudor Jones—aka Ninja—and Yo-Landi Visser of the South African rap-rave group Die Antwoord) and their confederate Yankie (Joe Pablo Cantillo). They originally planned to kidnap Deon and force him to turn off all the Scouts, but with Chappie now in their control, they plan to turn the bot into a criminal, too. Meanwhile Moore is out to undermine the Scout program entirely so that his Moose can save the day.

Blomkamp wants his movie to be many things at once—a sweet fable about a metallic Pinocchio, a parable about what makes us human, a screed against corporate greed, and a straight-up action movie. It fails in every respect. As the story of a machine that wants to become a real boy, it has about as much charm as Roberto Benigni’s “Pinocchio” did—none. Its supposedly human characters (even Deon, whom we’re meant to sympathize with) are all such dreary or repulsive creatures that it would seem best if the entire species were replaced by robots. Its observations about weapons manufacturing are empty, given the fact that it so often turns into an orgy of mindless mayhem itself; yet even those segments are terribly done, so that it doesn’t even succeed on that crummy level.

It’s too bad that Chappie himself is such an unappealing bucket of bolts, irritatingly voiced by Copley, but still he seems a delightful fellow beside Ninja and Yolandi, who would be intolerable even if they were peripheral characters but are practically the stars of the movie, and played so horribly by the rappers that their gross amateurishness appears to have infected old pros Weaver and Jackman, who give what are certainly among the worst performances of their careers. That leaves Petal, who’s not quite as over-the-top as he is in “The Second Best Exotic Marigold Hotel” (his second opening of the week), but not for lack of trying.

“Chappie” doesn’t even look good. The robot design is adequate if uninspired (with Moose coming across as particularly generic), and the CGI placement of the title character within live-action footage is certainly expert. But the backgrounds are depressingly grubby. That’s partially because Blomkamp, as usual, situates the tale in a dystopian future in which great hordes of people seem ready to go berserk at the drop of a hat, but that doesn’t explain why even the headquarters of Transvaal and the interior of Deon’s apartment (stocked with ultra-cute R2-D2-type help-bots) are so bland; Jules Cook’s production design is simply unimaginative. Nor does Trent Opaloch’s cinematography help: the washed-out, grime-filled images are just not very interesting to watch for two hours. And Hans Zimmer’s score, especially in the climactic finale reel, is typically oppressive.

The denouement, incidentally, suggests that Blomkamp might have had in mind a franchise along the lines of a robot-based “Planet of the Apes.” The negative response that “Chappie” is likely to receive should, thank heaven, toss that notion into the dustbin where it belongs.