Shuuichi Buma

Consideration of a human dynamic characteristic and performance evaluation of an electric active suspension

A rotary actuator type electric active suspension system, adopted for the investigation, enable to control roll, pitch, and bounce. The system allows controlling the vehicle attitude by an inertial input logic while sky-hook logic improves ride comfort. Actual vehicle motion control effects on the driverspsila reaction were investigated. Driverspsila reaction differences were examined on the slalom driving under the active suspension-produced small and large roll angles. A roll oscillation simulator is set up in order to investigate influence of the roll angle which side acceleration of cornering does not act on. The simulator is applied to analyze the driverspsila adjusting characteristics under several roll angles and to examine driverspsila movement optimization. Analyzed results and consideration of the human characteristics are reported in the active suspension mounted vehicle case and the simulator case.

On the Structural Simplification, Compact and Light Design of a Vehicle Suspension, Achieved by Using a Colloidal Cylinder with a Dual Function of Absorber and Compression-Spring

Classical suspension (oil damper mounted in parallel with compression helical spring) is replaced by a colloidal suspension, in which case the spring can be omitted. Hence, structural simplification, accompanied by a compact and lighter design can be achieved. Oil is replaced by an ecological mixture of water and water-repellent nanoporous particles of silica (artificial sand). Travel tests using a V8 4.3L auto vehicle equipped with classical and colloidal suspensions were performed. Ride comfort (ISO 2631 method) was evaluated during travel (speed: 5–40 km/h) on a normal road with an asphalt step (height: 37 mm; width: 405 mm), for various values of the tire inflation pressure (150–250 kPa). On normal road without step the travel speed was increased up to 80 km/h. Acceleration at seat, seat-back, and feet surfaces was processed using the commercially available DEICY system for ride comfort evaluation. Spring omission, accompanied by 60 % reduction of the outer diameter, and 30 % reduction of the mass was achieved both for the frontal and rear colloidal suspensions. Results concerning the ride comfort were validated in the case of classical suspensions. Relationship between the travel speed of the vehicle and level of vibration perception was obtained for various values of the tire inflation pressure. Ride comfort decreased at augmentation of the travel speed and the tire inflation pressure. Since the colloidal spring constant was 6 times larger than the constant of the compression helical spring, colloidal suspension provided 1 rank lower ride comfort than the classical suspension. Pitching and rolling movements were not considered during the estimation of the ride comfort. Relation between the lateral acceleration and the rolling attitude angle was experimentally determined. Ride comfort results were explained by taking into account the vehicle behaviour during frontal, rear and superimposed impact excitations, in correlation with the variation against travel speed of the frequency weighting proposed by the ISO 2631. Although the colloidal suspension was found to provide inferior ride comfort than the classical suspension, results obtained so far are encouraging since better performances are to be expected by softening the colloidal spring, and by redesigning the suspension including the stabilizers.

Preview Ride Comfort Control for Electric Active Suspension

A preview control that acts in accordance with the road surface profile in front of the vehicle has been proposed as a way to enhance ride comfort. Although the effectiveness of this control has been verified, many issues remain to be resolved, including improving the road surface profile estimation accuracy while the vehicle is in motion. Consequently, as a way of enhancing the comfort of the vehicle and reducing energy consumption, this development aimed to construct preview ride comfort control logic capable of estimating road surface displacement more accurately. To improve estimation accuracy, this paper proposes a method of estimating the road surface displacement in front of the vehicle using preview sensors and the body displacement estimated using a full-order observer. It describes sky-hook control logic that performs feed-forward of control amounts proportionally to the lateral road surface displacement. The ride comfort performance in the roll direction and the energy-saving effect of this control was verified using a 4-wheel shaker and in actual driving tests. It was confirmed that the developed control estimates road surface displacement more accurately than the previous control, thereby improving ride comfort at low-frequencies and reducing energy consumption. The result is a more feasible preview control system that has made progress toward the aim of practical application.

The application of CAE tools in the development of an Active Stabilizer Suspension System

In this paper we describe the application of computer aided engineering (CAE) tools in the development of an Active Stabilizer Suspension System, which has been developed to control the roll attitude and improve the stability of the vehicle.