Resumen
[0001] The subject matter of the invention is an articulation (1) with controllable stiffness and a force-measuring system, comprising a first device (20) that comprises a frame (4) having a curved face and connected to a first motor element (2), the first device (20) regulating the position of the articulation (1), and a second device (22) that regulates the stiffness of the articulation (1) and comprises a thrust element (15), the movement (D) of which determines the pre-compression of a resistive element (11) and thus the stiffness of the articulation (1); the first motor element (2) causes the frame (4) to rotate such that a wheel (8) of the second device (22) rolls on the curved face of the frame (4), causing the resistive element (11) to be compressed (C) via a transmission rod (7) associated with said wheel (8) and with the resistive element (11).
Reivindicaciones
1. An articulation (1) with controllable stiffness and force measuring device,characterised in that it comprises two devices: - a first device (20) comprising a frame (4) connected to a first motor element (2), this first device (20) performing the regulation of the position of the articulation (1), - a second device (22) which regulates the stiffness of the articulation (1) and which acts as an anchorage for the first device (20) to the articulation (1), comprising: - a coupling body (13) on which the other components of the second device (22) are arranged, - a resistive element (11), - a transmission rod (7) attached, at one end, to the resistive element (11) and comprising a wheel (8) at the opposite end, - a thrust element (15) with a threaded spindle (16) through it, on which the resistive element (11) rests, - a second motor (12) attached to the spindle (16), which provides a displacement (D) to the thrust element (15) by a rotation of said spindle (16), wherein the displacement D of the thrust element (15) determines a pre-compression of the resistive element (11), thus determining the articulation (1) stiffness, and the first motor element (2) provides a rotation to the frame (4) of the first device, wherein the frame (4) has a curved face, such that, with the rotation of the frame (4), the wheel (8) of the second device (22) rolls on the curved face of the frame (4), and the transmission rod (7) associated with said wheel (8) causes a compression (C) of the resistive element (11) of the second device (22), so this compression (C) and the velocity at which it occurs determines a force developed by the resistive element (11) known as F<thrust> . 2. The articulation (1) with controllable stiffness and force measuring device, according to Claim 1,characterised in that the resistive element (11) comprises an element selected from an elastic element with an own constant K, a shock absorber element with an own constant A, and a combination thereof. 3. The articulation (1) with controllable stiffness and force measuring device, according to any of the preceding claims,characterised in that the second device (21) comprises a rotational measuring element (17) connected to the second motor (12), said rotational measuring element (17) counting the revolutions of a shaft of the second motor (12) such that the displacement (D) of the thrust element (15) is known by performing a conversion of the revolutions of the second motor (12) and of the pitch of the spindle (16), where a revolution of the second motor (12) is equivalent to the pitch of the spindle (16) in the linear displacement of the thrust element (15) associated with the spindle (16), so that the displacement (D) of the thrust element (15) is known by the relationD = Revolutions ·Pitch. 4. The articulation (1) with controllable stiffness and force measuring device, according to Claim 3,characterised in that the second device (22) comprises a linear measurement element (9) and a graduated scale (10) attached to the transmission rod (7), such that compression experienced by the resistive element (11), and the velocity at which it occurs, associated to the rotation of the frame (4) is known through the linear measurement element (9), which measures the displacement of the transmission rod (7) on the graduated scale (7). 5. The articulation (1) with controllable stiffness and force measuring device, according to any of the preceding claims,characterised in that it takes advantage of the resistive element (11) associated with its stiffness to obtain the measure of a torque generated at the articulation (1) by the relation: Torque = b → × F → n , which is converted to Torque = b ‾ • F n − sin ϕ * <img class="EMIRef" id="471832623-ib0018" /> where -b is a vector that represents a distance between an articulation rotation axis (O) and a point of contact of the frame (4) with the wheel (8), and -Fn is the contact force between the surfaces of the frame (4) and of the wheel (8) in the radial direction of the wheel (8); -ϕ * is an angle between the vector b and the vectorFn , where - b is obtained from the relation: b ‾ = OB 2 ‾ + R 2 − 2 ⋅ OB ‾ ⋅ R ⋅ cos β <img class="EMIRef" id="471832623-ib0019" /> where β is the complementary angle which defines the inclination of the vector of the contact forceFn , and is obtained by the relation β = OA ‾ • sinθ BA ‾ , <img class="EMIRef" id="471832623-ib0020" /> where θ is the deflection angle obtained from θ = acos OB 2 ‾ + OA ‾ 2 − BA ‾ 2 2 OB ‾ ⋅ OA ‾ , <img class="EMIRef" id="471832623-ib0021" /> where: - OB : distance from the rotation axis of the articulation (1) to the centre of curvature of the frame (B); - OA : distance from the articulation rotation axis (O) to the centre of the wheel (A); - BA : distance from the centre of the curvature of the frame (B) to the centre of the wheel (A). -ϕ * is obtained from the expression ϕ *=β + ϕ + θ, where − ϕ = arccos b ‾ 2 + OA ‾ 2 − r 2 2 ⋅ b ‾ ⋅ OA ‾ <img class="EMIRef" id="471832623-ib0022" /> − Fn = F thrust cos ϕ where: F thrust = K • C + A • Vel whereK and A are the constant characteristic of the resistive element (11), C is the compression of the resistive element (11) and Vel is the velocity at which such compression occurs in the resistive element (11). 6. The articulation (1) with controllable stiffness and force measuring device, according to any of the preceding claims,characterised in that the first device (20) comprises, in addition to the frame (4) and the first motor element (2): - a reducer (3) having an stationary part and an outlet part, the frame (4) being connected to the stationary part of the reducer (3), - a first disc (6) connected to the reducer output (3), - a second disk (5), connected to the frame (4), into which the first disc (6) is inserted. 7. The articulation (1) with controllable stiffness and force measuring device, according to any of the preceding claims,characterised in that the coupling body (13) of the second device (22) comprises guide channels (14) that guide the movement of the thrust element (15) and through-holes (21), with the transmission rod (7) passing through these through-holes (21). 8. The articulation (1) with controllable stiffness and force measuring device, according to any of the preceding claims,characterised in that the thrust element (15) is a flat piece, whose movement is limited by the guide channels (14) of the coupling body (13) of the second device (22).
