diff --git a/gtsam_unstable/dynamics/VelocityConstraint3.h b/gtsam_unstable/dynamics/VelocityConstraint3.h
new file mode 100644
index 000000000..24d866829
--- /dev/null
+++ b/gtsam_unstable/dynamics/VelocityConstraint3.h
@@ -0,0 +1,62 @@
+/**
+ * @file VelocityConstraint3.h
+ * @brief A simple 3-way factor constraining LieScalar poses and velocity
+ * @author Duy-Nguyen Ta
+ */
+
+#pragma once
+
+#include <gtsam/base/LieScalar.h>
+#include <gtsam/nonlinear/NonlinearFactor.h>
+
+namespace gtsam {
+
+class VelocityConstraint3 : public NoiseModelFactor3<LieScalar, LieScalar, LieScalar> {
+public:
+
+protected:
+  typedef NoiseModelFactor3<LieScalar, LieScalar, LieScalar> Base;
+
+  /** default constructor to allow for serialization */
+  VelocityConstraint3() {}
+
+  double dt_;
+
+public:
+
+  typedef boost::shared_ptr<VelocityConstraint3 > shared_ptr;
+
+  ///TODO: comment
+  VelocityConstraint3(Key key1, Key key2, Key velKey, double dt, double mu = 1000.0)
+  : Base(noiseModel::Constrained::All(LieScalar::Dim(), fabs(mu)), key1, key2, velKey), dt_(dt) {}
+  virtual ~VelocityConstraint3() {}
+
+  /// @return a deep copy of this factor
+  virtual gtsam::NonlinearFactor::shared_ptr clone() const {
+    return boost::static_pointer_cast<gtsam::NonlinearFactor>(
+        gtsam::NonlinearFactor::shared_ptr(new VelocityConstraint3(*this))); }
+
+  /** g(x) with optional derivative2 */
+  Vector evaluateError(const LieScalar& x1, const LieScalar& x2, const LieScalar& v,
+      boost::optional<Matrix&> H1 = boost::none,
+      boost::optional<Matrix&> H2 = boost::none,
+      boost::optional<Matrix&> H3 = boost::none) const {
+    const size_t p = LieScalar::Dim();
+    if (H1) *H1 = eye(p);
+    if (H2) *H2 = -eye(p);
+    if (H3) *H3 = eye(p)*dt_;
+    return x2.localCoordinates(x1.compose(LieScalar(v*dt_)));
+  }
+
+private:
+
+  /** Serialization function */
+  friend class boost::serialization::access;
+  template<class ARCHIVE>
+  void serialize(ARCHIVE & ar, const unsigned int version) {
+    ar & boost::serialization::make_nvp("NoiseModelFactor3",
+        boost::serialization::base_object<Base>(*this));
+  }
+}; // \VelocityConstraint3
+
+}
diff --git a/gtsam_unstable/dynamics/tests/testVelocityConstraint3.cpp b/gtsam_unstable/dynamics/tests/testVelocityConstraint3.cpp
new file mode 100644
index 000000000..21701fda4
--- /dev/null
+++ b/gtsam_unstable/dynamics/tests/testVelocityConstraint3.cpp
@@ -0,0 +1,31 @@
+/**
+ * @file testVelocityConstraint3
+ * @author Duy-Nguyen Ta
+ */
+
+#include <CppUnitLite/TestHarness.h>
+
+#include <gtsam_unstable/dynamics/VelocityConstraint3.h>
+
+/* ************************************************************************* */
+using namespace gtsam;
+
+const double tol=1e-5;
+const double dt = 1.0;
+
+LieScalar origin,
+        x1(1.0), x2(2.0), v(1.0);
+
+/* ************************************************************************* */
+TEST( testVelocityConstraint3, evaluateError) {
+  // hard constraints don't need a noise model
+  VelocityConstraint3 constraint(x1, x2, v, dt);
+
+  // verify error function
+  EXPECT(assert_equal(zero(1), constraint.evaluateError(x1, x2, v), tol));
+}
+
+
+/* ************************************************************************* */
+int main() { TestResult tr; return TestRegistry::runAllTests(tr); }
+/* ************************************************************************* */