Force feedback input device

A force feedback input device includes an operation member having a shaft and operated by an operator, detection means, such as a rotary encoder, for detecting an operating status of the operation member, an actuator for providing force feedback to the operation member, control means for controlling the actuator based on a detection signal output from the detection means, and stopper means for restricting displacement of the operation member in a predetermined operational direction. The stopper means includes a ratchet mechanism to disengage ratchets from corresponding gear teeth in response to the detection signal from the detection means.

This application claims the benefit of priority to Japanese Patent Application No. 2003-193694, herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a force feedback input device in which force feedback is provided to an operation member of the force feedback input device in accordance with the operating status and, in particular, to a stopper mechanism to restrict excessive displacement of the operation member.

2. Description of the Related Art

As input devices applied to, for example, a central “by-wire” control system of in-car electronic devices, a steer-by-wire steering system, a shift-by-wire gear change system, and a brake-by-wire braking system, force feedback input devices are known which includes an operation member that an operator manually operates, detection means, such as a position sensor, for detecting the operating status of the operation member, an actuator for providing force feedback to the operation member, and control means for controlling the actuator based on detection signals output from the detection means (refer to, for example, Japanese Unexamined Patent Application Publication No. 2002-149324, in particular, pages 3 to 5, and FIG. 3). Such force feedback input devices can provide various types of force feedback to the operation member in accordance with the direction and amount of movement of the operation member, and thereby can provide desired operation feeling to operations of the by-wire devices.

In these force feedback input devices, when the operation member is operated to an allowed maximum displacement, further displacement must be limited. To limit the displacement, a simple stopper mechanism is widely employed in which part of the operation member is brought into contact with a stopper fixed at a predetermined position.

Unfortunately, in the case where the allowed operations range, namely, the moving range of the operation member varies in accordance with use conditions, a stopper mechanism capable of changing the position of the stopper is essential to restrict excessive displacement of the operation member. In one known force feedback input device having this type of stopper, a rotary motor functions as an actuator that provides feedback force, such as sense of resistance, to the operation member, and the resistance force is increased by applying a large electric current to the motor when the operation member is displaced to an allowed limit of the operation range. However, since the known force feedback input device must apply a large electric current every time the operation member is displaced to an allowed limit of the operation range, power consumption is undesirably increased, which is a problem. In addition, the control method that increases the resistance force by applying a large electric current to the motor does not produce a distinct sense indicating that no more displacement of the operation member is possible, also referred to as “wall effect”. Consequently, this method does not provide satisfactory operability.

Some force feedback input devices are proposed to restrict undesirably increased power consumption by providing an electromagnetic brake, separately from the motor which provides force feedback to the operation member. According to this proposal, since the electromagnetic brake can easily produce a large braking force, the displacement of the operation member can be instantly stopped at a predetermined position. In practice, the reverse displacement of the operation member whose excessive displacement is limited must not be restricted. As a result, the braking force of the electromagnetic brake must not be too strong and, therefore, this force feedback input device cannot provide satisfactory operability.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a force feedback input device that can limit the excessive displacement of an operation member at a stopper position while providing a wall effect, can appropriately change the stopper position, and can reduce power consumption.

According to the present invention, a force feedback input device includes an operation member operated by an operator, detection means for detecting an operating status of the operation member, an actuator for providing force feedback to the operation member, control means for controlling the actuator based on a detection signal output from the detection means, and stopper means for restricting displacement of the operation member in a predetermined operational direction. The stopper means has a ratchet mechanism to disengage a ratchet from gear teeth and the disengagement is performed based on the detection signal.

In the force feedback input device including the stopper means with the ratchet mechanism, at the moment when the detection means detects the displacement of the operation member that is exceeding the allowed operation limit, the ratchet of the stopper means is engaged with the corresponding gear teeth. As a result, this instantly restricts excessive displacement of the operation member while allowing the operation member to be displaced in the opposite direction (a “push back” operation) and, therefore, produces a wall effect and superior operability. Additionally, since a large electric current is not required for disengaging the ratchet from the gear teeth, the stopper means can be operated at low power consumption. Furthermore, if the allowed operation range of the operation member is altered, a stopping position of the operation member can be readily changed by controlling a driving signal for the ratchet mechanism of the stopper means.

In the force feedback input device, the gear teeth of the ratchet mechanism in the stopper means are preferably mounted on the operation member, and thereby the ratchet mechanism has a simple and reliable structure in which a ratchet is disengaged from the gear teeth movable along with the operation member.

Additionally, in the force feedback input device according to the present invention, the ratchet mechanism of the stopper means may include a first ratchet for restricting displacement of the operation member in one direction and a second ratchet for restricting displacement of the operation member in the opposite direction. The first ratchet can be engaged with corresponding gear teeth when the operation member is operated and is displaced to the allowed limit of the operation range in one direction. Also, the second ratchet can be engaged with corresponding gear teeth when the operation member is operated and is displaced to the allowed limit of the operation range in the opposite direction. Accordingly, the movement of the operation member can be reliably restricted at both ends of the operation range with a wall effect.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present invention will now be described with reference to the accompanying drawings.FIG. 1is a block diagram of the entire force feedback input device according to the embodiment.FIG. 2is a view of a relevant portion of stopper means in the force feedback input device.

In the force feedback input device according to the embodiment, an operation member is pivotally operated by hand. The force feedback input device includes a support plate1; a bearing2fixedly mounted on the support plate1; an pivotally movable operation member3with a protruding shaft4rotatably supported by the bearing2; an actuator5which provides force feedback to the operation member3, a rotary encoder6which detects the operating status of the operation member3; control means7which outputs driving signals b and c, and a command signal d based on a detection signal a from the rotary encoder6; and stopper means8which limits displacement of the operation member3in a predetermined direction of the operation. An external device, which is a target of the operation by the operation member3, is controlled by driving signals output from an external controller30. The external controller30is controlled by the signal d.

The driving signal b is output from the control means7in response to the detection signal a from the rotary encoder6, and is input to the actuator5. The driving signal b allows the actuator5to provide force feedback, such as sense of resistance and vibration, to the operation member3operated pivotally. In this embodiment, the actuator5includes a rotary motor, however, it may include a linear motor or a solenoid.

The rotary encoder6includes a code plate (not shown) which rotates along with the shaft4and a photo interrupter (not shown) which reads a detection pattern disposed on the code plate. The rotary encoder6can detect the rotation direction and amount of rotation (rotation angle) of the shaft4while the operation member3is pivotally operated. However, other detection means (position sensors) may be employed instead of the rotary encoder.

The control means7includes an input unit71that receives the detection signal a output from the rotary encoder6; a memory unit72that stores control signals corresponding to the operating status of the operation member3; a CPU73that reads, from the memory unit72, a control signal corresponding to the detection signal a received by the input unit71and outputs it; a driver circuit74which generates the driving signals b and c and the command signal d by D/A-converting the signal output from the CPU73and amplifying it; and an output unit75which outputs the driving signals b and c to the actuator5and the stopper means8, respectively, and also outputs the command signal d to the external controller30.

The stopper means8includes a ratchet mechanism shown inFIG. 2. The ratchet mechanism includes an engaging plate80which has two groups of gear teeth81and82and is coupled to the shaft4of the operation member3, and first and second ratchets83and84which are releasably engaged with the gear teeth81and82, respectively. Also, the ratchet mechanism includes a pair of solenoids85and86which drive the ratchets83and84, respectively. The driving signal c, which is output from the control means7in response to the detection signal a from the rotary encoder6, is selectively input to the solenoid85or86to drive the ratchet83or84, respectively. When the first ratchet83is driven by the solenoid85, the ratchet83is engaged with the corresponding gear teeth81and restricts the rotation of the shaft4in one direction. Accordingly, the operation member3cannot be operated in the one direction. In contrast, when the second ratchet84is driven by the solenoid86, the ratchet84is engaged with the corresponding gear teeth82and restricts the rotation of the shaft4in the other direction. Accordingly, the operation member3cannot be operated in the other direction.

That is, when the operation member3is operated to rotate in one direction and is displaced to the allowed limit of the operation range, the rotary encoder6detects the displacement of the operation member3. The solenoid85is then driven to engage the first ratchet83with the gear teeth81and thereby the operation member3is instantly no longer allowed to be displaced in that direction. At this moment, the operation member3is not restricted to rotate in the opposite direction, thus, an operator can feel a wall effect. Likewise, when the operation member3is operated to rotate in the other direction and is displaced to the allowed limit of the operation range, the solenoid86is driven to engage the second ratchet84with the gear teeth82and thereby the operation member3is limited not to be excessively displaced in that direction. Accordingly, a wall effect is also produced.

Thus, in the force feedback input device according to the embodiment, at the moment when the rotary encoder6detects the rotational displacement of the operation member3that is exceeding the allowed operation limit, the ratchet83or84of the stopper means8is engaged with the corresponding gear teeth81or82, respectively. As a result, this instantly restricts excessive displacement of the operation member3while allowing the operation member3to be displaced in the opposite direction (a “push back” operation) and, therefore, produces a wall effect and superior operability. Additionally, since a large electric current is not required for driving the ratchets83or84, the stopper means8can be operated at low power consumption. Furthermore, if the allowed operation range of the operation member3is altered, a stopping position of the stopper in the operation member3can be readily changed by controlling the driving signal for the ratchet mechanism of the stopper means8.

In the above-described embodiment, a pair of the solenoids85and86is used to actuate the first and second ratchet83and84; however, a single solenoid may actuate the ratchets83and84. Additionally, the stopper means8may include a one-way electromagnetic clutch having a ratchet mechanism.

Furthermore, in the above-described embodiment, a force feedback input device having a pivotally operated operation member is described. In addition to this type of force feedback input device, the present invention can be applied to a force feedback input device having a rotatably operated operation member.