<xr-camera
      id="camera" position="0 20 -35" clear-color="0 0 0 1"
      target="target"
      background="ar" 
      camera-orbit-control="{{bControl}}"
 ></xr-camera>

 const camEl = this.scene.getElementById('camera');
 this.camera = camEl.getComponent(wx.getXrFrameSystem().Camera);
 this.cameraCtrl = camEl.getComponent('camera-orbit-control');
 this.cameraCtrl.disable();

以上都试过了没用