Add tendon actuator force limits and tendon actuator force sensor.

PiperOrigin-RevId: 745096883
Change-Id: Ib9acb727fbbfc6b0b0323ee6a889053a7a878056

src/user/user_objects.cc

@@ -5388,7 +5388,9 @@ mjCTendon& mjCTendon::operator=(const mjCTendon& other) {
 bool mjCTendon::is_limited() const {
   return islimited(limited, range);
 }
-
+bool mjCTendon::is_actfrclimited() const {
+  return islimited(actfrclimited, actfrcrange);
+}
 
 void mjCTendon::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
@@ -5686,6 +5688,21 @@ void mjCTendon::Compile(void) {
     throw mjCError(this, "invalid limits in tendon");
   }
 
+  // if limited is auto, set to 1 if range is specified, otherwise unlimited
+  if (actfrclimited == mjLIMITED_AUTO) {
+    bool hasactfrcrange = !(actfrcrange[0] == 0 && actfrcrange[1] == 0);
+    checklimited(this, compiler->autolimits, "tendon", "", actfrclimited,
+                 hasactfrcrange);
+  }
+
+  // check actfrclimits
+  if (actfrcrange[0] >= actfrcrange[1] && is_actfrclimited()) {
+    throw mjCError(this, "invalid actuatorfrcrange in tendon");
+  }
+  if ((actfrcrange[0] > 0 || actfrcrange[1] < 0) && is_actfrclimited()) {
+    throw mjCError(this, "invalid actuatorfrcrange in tendon");
+  }
+
   // check springlength
   if (springlength[0] > springlength[1]) {
     throw mjCError(this, "invalid springlength in tendon");
@@ -6479,6 +6496,18 @@ void mjCSensor::Compile(void) {
       }
       break;
 
+  case mjSENS_TENDONACTFRC:
+    // must be attached to tendon
+    if (objtype != mjOBJ_TENDON) {
+      throw mjCError(this, "sensor must be attached to tendon");
+    }
+
+    // set
+    dim = 1;
+    datatype = mjDATATYPE_REAL;
+    needstage = mjSTAGE_ACC;
+    break;
+
     case mjSENS_TENDONPOS:
     case mjSENS_TENDONVEL:
       // must be attached to tendon