Add touch sensor for estimating the surface contact stresses from the SDF.

PiperOrigin-RevId: 758556339 Change-Id: Ib56d76fab084b530fd68d61a29294cb6f1d05f3f
2025-05-14 00:45:05 -07:00
parent 23865c7491
commit 2386dfd7da
11 changed files with 779 additions and 8 deletions
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+// Copyright 2025 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef MUJOCO_PLUGIN_SENSOR_TOUCH_STRESS_H_
+#define MUJOCO_PLUGIN_SENSOR_TOUCH_STRESS_H_
+
+#include <vector>
+
+#include <mujoco/mjdata.h>
+#include <mujoco/mjmodel.h>
+#include <mujoco/mjtnum.h>
+#include <mujoco/mjvisualize.h>
+
+namespace mujoco::plugin::sensor {
+
+// A touch grid sensor is associated with a site and senses contact stresses
+// between the site's parent body and all other bodies. The site's
+// frame determines the orientation of the sensor with the same convention used
+// for cameras and lights: the sensor points in the frame's negative-Z
+// direction, so the X and Y axes correspond to horizontal and vertical
+// directions respectively.
+//
+// The output of the sensor is a stack of 3 "touch images" corresponding to
+// forces in the local frame of the taxels. Forces are in the [z, x, y] order,
+// corresponding to the ordering in contact frames: [normal, tangent, tangent].
+//
+// The sensor has 6 parameters:
+//  1. (int) Number of channels [1-3]. Defaults to 1.
+//  2. (int) Horizontal resolution.
+//  3. (int) Vertical resolution.
+//  4. (float) Horizontal field-of-view (fov_x), in degrees.
+//  5. (float) Vertical field-of-view (fov_y), in degrees.
+//  6. (float) Foveal deformation. Defaults to 0.
+class TouchStress {
+ public:
+  static TouchStress* Create(const mjModel* m, mjData* d, int instance);
+  TouchStress(TouchStress&&) = default;
+  ~TouchStress() = default;
+
+  void Reset(const mjModel* m, int instance);
+  void Compute(const mjModel* m, mjData* d, int instance);
+  void Visualize(const mjModel* m, mjData* d, const mjvOption* opt,
+                 mjvScene* scn, int instance);
+
+  static void RegisterPlugin();
+
+  int nchannel_;           // number of channels (1-3)
+  int size_[2];            // horizontal and vertical resolution
+  mjtNum fov_[2];          // horizontal and vertical field of view, in degrees
+  mjtNum gamma_;           // foveal deformation
+
+ private:
+  TouchStress(const mjModel* m, mjData* d, int instance, int nchannel,
+               int* size, mjtNum* fov_x, mjtNum gamma);
+
+  std::vector<mjtNum> x_edges_;
+  std::vector<mjtNum> y_edges_;
+  std::vector<mjtNum> dist_;
+  std::vector<mjtNum> pos_;
+  std::vector<mjtNum> mat_;
+
+  int id_;
+  int parent_weld_;
+  int geom_id_;
+};
+
+}  // namespace mujoco::plugin::sensor
+
+#endif  // MUJOCO_PLUGIN_SENSOR_TOUCH_STRESS_H_