bm_right = beamsweep(this, this.origin, vr, length, step, step_up, step_down);
bm_left = beamsweep(this, this.origin, vl, length, step, step_up, step_down);
bm_right = beamsweep(this, this.origin, vr, length, step, step_up, step_down);
bm_left = beamsweep(this, this.origin, vl, length, step, step_up, step_down);