초록 ▼

Alignment device adapted to measure characteristic angles of the wheels and of the steering of motor vehicles, particularly camber, toe-in, caster, by way of arms provided with sensors to be fastened to the wheels. In particular, in the step for determining the mounting error of the grip elements (r

Alignment device adapted to measure characteristic angles of the wheels and of the steering of motor vehicles, particularly camber, toe-in, caster, by way of arms provided with sensors to be fastened to the wheels. In particular, in the step for determining the mounting error of the grip elements (runout), the level sensor is used to measure the wheel rotation angle and methods for compensating the measurements performed when the arms are at a nonzero level are then applied.

대표청구항 ▼

1. A wheel alignment device, comprising: measurement arms, which are rigidly fixed to respective grip elements, said grip elements being adapted to be fixed rigidly to wheels of a vehicle, so that the arms can turn rigidly with the wheels;said arms comprising sensors arranged so as to measure relati

1. A wheel alignment device, comprising: measurement arms, which are rigidly fixed to respective grip elements, said grip elements being adapted to be fixed rigidly to wheels of a vehicle, so that the arms can turn rigidly with the wheels;said arms comprising sensors arranged so as to measure relative angles between the wheels and/or angles of the wheels with respect to gravity, said sensors comprising at least one sensor for measuring a level angle λm;a calculation unit connected to said sensors, for computing characteristic angles of the vehicle, calculated starting from measurements generated by said sensors and acquired by said calculation unit, said calculation unit comprising:means for calculating a wheel rotation angle on the basis of the measurement generated by the level sensor;leveling compensation means for compensating first measurements generated by said sensors for measurement errors of said sensors caused by the possible lack of a level orientation of said arms turning rigidly with the wheels of a vehicle before each measurement acquired by said calculation unit;means for calculating runout errors starting from the measurements compensated by said leveling compensation means;runout compensation means for compensating for said runout errors second measurements generated by said sensors and acquired by said calculation unit. 2. The alignment device according to claim 1, wherein said arm sensors comprise, in addition to the level sensor, at least one among: a camber inclinometer, a toe-in sensor, an alignment sensor, a toe-in emitter and an alignment emitter. 3. The alignment device according to claim 2, wherein said arm sensors further comprise at least one of the following: an optical perpendicular toe-in sensor, which is autonomous with respect to the toe-in sensor or is fitted together with the toe-in sensor in a two-dimensional device; an optical perpendicular alignment sensor, which is autonomous with respect to the alignment sensor or is fitted together with the alignment sensor in a two-dimensional device; an optical wheel base and gage sensor, for measuring the distance of the opposite arms with respect to the wheel base and with respect to the gage; further light emitters to allow the sensors to measure multiple angles. 4. The alignment device according to claim 3, wherein the measurement arms fitted to the rear wheels of the vehicle have no toe-in sensors. 5. The device according to claim 1, wherein said level sensor is a MEMS (Micro Electro-Mechanical System) accelerometer. 6. A wheel alignment device, comprising: measurement arms, which are rigidly fixed to respective grip elements, said grip elements being adapted to be fixed rigidly to wheels of a vehicle, so that the arms can turn rigidly with the wheels;said arms comprising sensors arranged so as to measure relative angles between the wheels and/or angles of the wheels with respect to gravity, said sensors comprising at least one sensor for measuring a level angle λm;a calculation unit connected to said sensors, for computing characteristic angles of the vehicle, calculated starting from measurements generated by said sensors and acquired by said calculation unit, said calculation unit comprising:means for calculating a wheel rotation angle on the basis of the measurement generated by the level sensor;leveling compensation means for compensating first measurements generated by said sensors for measurement errors of said sensors caused by the possible lack of a level orientation of said arms before each measurement acquired by said calculation unit;means for calculating runout errors starting from the measurements compensated by said leveling compensation means;runout compensation means for compensating for said runout errors second measurements generated by said sensors and acquired by said calculation unit;the arms comprising, in addition to said at least one level sensor, at least one alignment sensor and an alignment emitter for measuring an alignment angle αm, said leveling compensation means being adapted to calculate the solutions of the system: { axF⁡(αF,αR)⁢tan⁡(αmF)+ayF⁡(αF,αR)=0axR⁡(αF,αR)⁢tan⁡(αmR)+ayR⁡(αF,αR)=0 where, given a pair of arms mounted on wheels on the same right or left side of the vehicle, the unknowns αF and αR are the compensated alignment angles respectively of the front arm and of the rear arm of the pair,αmF and αmR are the measured alignment angles respectively of the front arm and of the rear arm of the pair,αxF and αyF are the x and y coordinates, in a reference system OFxmFymFzmF of the front arm, of the vector αF which connects the alignment emitter of the rear arm of the pair to the alignment sensor of the front arm of the pair;αxR and αyR are the x and y coordinates, in a reference system ORxmRymRzmR of the rear arm of the vector αR which connects the alignment emitter of the front arm of the pair to the alignment sensor of the rear arm of the pair, where said reference systems ORxmRymRzmR, OFxmFymFzmF each consist of a Cartesian set of three perpendicular axes which is rigidly coupled to the respective arm, wherein: the origin O is in the intersection point between a vertical axis z which passes through a contact point of the wheel and the axis of rotation of the respective arm;the axis xm is directed along the longitudinal axis of the respective arm, along its orientation;the axis ym is directed like the rotation axis of the respective arm and toward the outside of the vehicle;the axis zm is directed at right angles to xm and ym and upward. 7. A wheel alignment device, comprising: measurement arms, which are rigdly fixed to respective grip elements, said grip elements being adapted to be fixed rigidly to wheels of a vehicle, so that the arms can turn rigidly with the wheels;said arms comprising sensors arranged so as to measure relative angles between the wheels and/or angles of the wheels with respect to gravity, said sensors comprising at least one sensor for measuring a level angle λm;a calculation unit connected to said sensors, for computing characteristic angles of the vehicle, calculated starting from measurements generated by said sensors and acquired by said calculation unit, said calculation unit comprising:means for calculating a wheel rotation angle on the basis of the measurement generated by the level sensor;leveling compensation means for compensating first measurements generated by said sensors for measurement errors of said sensors caused by the possible lack of a level orientation of said arms before each measurement acquired by said calculation unit;means for calculating runout errors starting from the measurements compensated by said leveling compensation means;runout compensation means for compensating for said runout errors second measurements generated by said sensors and acquired by said calculation unit;said arms comprising, in addition to said at least one level sensor, at least one toe-in sensor and a toe-in emitter for measuring a toe-in angle τm, said leveling compensation means being adapted to calculate the solutions of the system: { tyL⁡(τL,τR)⁢tan⁡(τmL)+txL⁡(τL,τR)=0tyR⁡(τL,τR)⁢tan⁡(τmR)+txR⁡(τL,τR)=0 where, given a pair of arms mounted on front or rear wheels of the vehicle, the unknowns τL and τR are the compensated toe-in angles respectively of the left arm and of the right arm of the pair,τmL and τmR are the measured toe-in angles respectively of the left arm and of the rear arm of the pair,txL and tyL are the x and y coordinates, in a reference system OLxmLymLzmL of the left arm of the pair, of the vector tL which connects the toe-in emitter of the right arm of the pair to the toe-in sensor of the left arm of the pair;txR and tyR are the x and y coordinates, in a reference system ORxmRymRzmR of the right arm of the pair, of the vector tR which connects the toe-in emitter of the left arm of the pair to the toe-in sensor of the right arm of the pair; each of said arm reference systems consisting of a Cartesian set of three perpendicular axes OLxmLymLzmL, ORxmRymRzmR rigidly coupled to the respective arm, wherein: the origin is in the intersection point between a vertical axis z which passes through a contact point of the wheel and the axis of rotation of the respective arm;the axis xm is directed along the longitudinal axis of the respective arm, along its orientation;the axis ym is directed like the rotation axis of the respective arm and toward the outside of the vehicle;the axis zm is directed at right angles to xm and ym and upward. 8. A wheel alignment device, comprising: measurement arms, which are rigidly fixed to respective grip elements, said grip elements adapted to be fixed rigidly to wheels of a vehicle, so that the arms can turn rigidly with the wheels;said arms comprising sensors arranged so as to measure relative angles between the wheels and/or angles of the wheels with respect to gravity, said sensors comprising at least one sensor for measuring a level angle λm;a calculation unit connected to said sensors, for computing characteristic angles of the vehicle, calculated starting from measurements generated by said sensors and acquired by said calculation unit, said calculation unit comprising;means for calculating a wheel rotation angle on the basis of the measurement generated by the level sensor;leveling compensation means for compensating first measurements generated by said sensors for measurement errors of said sensors caused by the possible lack of a level orientation of said arms before each measurement acquired by said calculation unit;means for calculating runout errors starting from the measurements compensated by said leveling compensation means;runout compensation means for compensating for said runout errors second measurements generated by said sensors and acquired by said calculation unit;measurements compensated for runout error comprising at least one among a compensated camber angle γc, a compensated alignment angle αc and a compensated toe-in angle τc, which are defined as follows: γc=γ*−γr αf=α*−αr τf=τ*−τr where γrαr and τr are respectively camber, alignment and toe-in runout errors, calculated by said runout errors calculation means in a runout step starting from the measurements compensated by said leveling compensation means,γ*, α* and τ* are respectively the second camber, alignment and toe-in measurements acquired by said calculation unit to calculate said angles compensated for runout error and compensated for the leveling error by said leveling compensation means. 9. The device according to claim 8, comprising at least two sensors, of which at least the camber sensor and at least the alignment sensor or, as an alternative to the latter, at least the toe-in sensor, wherein said measurements compensated by said leveling compensation means are generated starting from first measurements acquired by said at least two sensors, in at least two positions, at different rotation angles, of the arms rigidly coupled to the wheels,said means for calculating runout errors γr, αr, τr are adapted to perform, for each pair of angular positions of the arms and therefore of the wheels and optionally averaging the results, the following calculations: γr=R·cos(θ+φ)αr=−R·sin(θ+φ)τr=−αr where: R=(x2+y2)ϕ=arc⁢⁢tan⁡(xy) where, if at least one alignment sensor is present x=k1·(γ1-γ2)-k2·(α1-α2)k12+k22y=k2·(γ1-γ2)+k1·(α1-α2)k12+k22 or, as an alternative, if at least one toe-in sensor is present x=k1·(γ1-γ2)+k2·(τ1-τ2)k12+k22y=k2·(γ1-γ2)-k1·(τ1-τ2)k12+k22 where k1=1−cos(λm2−λm1)k2=sin(λm2−λm3)θ=λm3−λm1) where γ1, α1, τ1 are said measurements compensated by said leveling compensation means, respectively for camber, alignment and toe-in, starting from the first measurements performed in one of the two angular positions of the arm;γ2, α2, τ2 are said measurements compensated by said leveling compensation means, respectively for camber and alignment, starting from the first measurements performed in the other of the two angular positions of the arm;λm1, λm2 are the level angles measured in the two angular positions of the arm;λm3 is the level angle measured at the end of the runout step, when the arms, and therefore the wheels, are motionless. 10. A method for determining the runout error, comprising the following steps: resting a vehicle on an auto lift or on another flat surface;rigidly connecting four arms to respective grip elements and rigidly connecting these last to respective wheels of the vehicle;moving the motor vehicle backward and/or forward;for each wheel, storing in at least two positions the camber, level and alignment measurements or, as an alternative to this last measurement, the toe-in measurement, or in at least three positions the camber and level measurements;calculating the runout errors by way of the runout error calculation means according to claim 9. 11. The method for determining the runout error according to claim 10, wherein: the arms are rigidly connected to the grip elements and the grip elements are rigidly connected to the wheels so that the front arms are substantially level and the rear arms are inclined with a level angle of approximately 15° with respect to the ground;the motor vehicle is moved backward until the rear arms reach a substantially level orientation, and angles of camber γ1, alignment α1, and level λ1 for each wheel are measured;the motor vehicle is moved forward until the wheels are returned to the initial position and angles of camber γ2, alignment α2 and level λ2 for each wheel are measured;further movements of the vehicle are prevented;the level angle λ3 is measured for each wheel;optionally, the rear arms are disconnected and reconnected to the wheels so that they are substantially level, so as to allow measurements of the subsequent steps. 12. The device according to claim 8, comprising: at least one sensor for measuring the camber angle γm, wherein said leveling compensation means are adapted to calculate a camber angle γ compensated for the error caused by lack of the level condition,said means for calculating runout errors γr, αr, τr are adapted to perform the following calculations, given the measurements of said at least one camber sensor and for each set of three angular positions of the arms, optionally averaging the results: γr=R·cos(θ+φ)αr=−R·sin(θ+φ)τr=−αr where: R=(x2+y2)ϕ=arctan⁡(xy)wherex=ks⁢⁢1·(γ1-γ3)-ks⁢⁢2·(γ1-γ2)ky=(1-ks⁢⁢2)·(γ1-γ2)-(1-ks⁢⁢1)·(γ1-γ3)k where: k=ks1·(1−kc2)−ks2·(1−kc1)kc1=cos(λm2−λm1)ks1=sin(λm2−λm1)kc2=cos(λm3−λm1)ks2=sin(λm3−λm1)θ=λm4−λm1 where γ1, γ2, γ3 are said camber measurements compensated by said leveling compensation means, starting from the first measurements performed in the three angular positions of a given arm;λm1, λm2, λm3 are the level angles measured in the three angular positions of the arm;λm4 is the level angle measured at the end of the runout step, when the arms are motionless. 13. A method for determining the runout error, comprising the following steps: resting a vehicle on an auto lift or on another flat surface;rigidly connecting four arms to respective grip elements and rigidly connecting these last to respective wheels of the vehicle;moving the motor vehicle backward and/or forward;for each wheel, storing in at least two positions the camber, level and alignment measurements or, as an alternative to this last measurement, the toe-in measurement, or in at least three positions the camber and level measurements;calculating the runout errors by way of the runout error calculation means according to claim 12. 14. A wheel alignment device, comprising: measurement arms, which are rigidly fixed to respective grip elements, said grip elements being adapted to be fixed rigidly to wheels of a vehicle, so that the arms turn rigidly with the wheels during a runout measurement step;said arms comprising sensors arranged so as to measure relative angles between the wheels and/or angles of the wheels with respect to gravity, said sensors comprising at least one accelerometer for measuring a level angle λm;a calculation unit connected to said sensors, for computing characteristic angles of the vehicle, calculated starting from measurements generated by said sensors and acquired by said calculation unit, said calculation unit comprising:means for calculating a wheel rotation angle on the basis of the measurement generated by the accelerometer;leveling compensation means for compensating first measurements generated by said sensors for measurement errors of said sensors caused by the possible lack of a level orientation of said arms turning rigidly with the wheels of a vehicle before each measurement acquired by said calculation unit;means for calculating runout errors starting from the measurements compensated by said leveling compensation means;runout compensation means for compensating for said runout errors second measurements generated by said sensors and acquired by said calculation unit.