采集SDK-Android　报错　small_detect.model　找不到

这是说明文档：https://ai.baidu.com/docs#/Face-Android-SDK/top

文档里完全没提到这个文件，我想知道这个文件在哪下载，有什么作用

以下为报错信息

E/FaceSDK: caffe_detect_model 2 ...
W/System.err: java.io.FileNotFoundException: small_detect.model
W/System.err: at android.content.res.AssetManager.openAsset(Native Method)
at android.content.res.AssetManager.open(AssetManager.java:318)
at android.content.res.AssetManager.open(AssetManager.java:292)
at com.baidu.idl.facesdk.BDFaceUtils.hasModel(BDFaceUtils.java:20)
at com.baidu.idl.facesdk.FaceTracker.(FaceTracker.java:71)
at com.baidu.idl.face.platform.FaceSDKManager.initialize(FaceSDKManager.java:47)
at com.yh.faceatt_client.MainActivity.initLib(MainActivity.java:47)
at com.yh.faceatt_client.MainActivity.onCreate(MainActivity.java:36)
at android.app.Activity.performCreate(Activity.java:6309)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1113)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2519)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2654)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1488)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5728)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679)