function make_cop_file(infile,outfile)

q=read_motionFile(infile);

I=find_columns_by_label(q.labels,'ground_force_px');

if length(I)~=2
	error('Expected two force plates');
end

out.labels = { 'time', ...
					'ground_force_px_r', 'ground_force_py_r', 'ground_force_pz_r', ...
					'ground_force_px_l', 'ground_force_py_l', 'ground_force_pz_l' };
out.data = [q.data(:,1) q.data(:,I(1)+(0:2)) q.data(:,I(2)+(0:2))];
write_motionFile(out,outfile);
